Actuality and Potentiality

Philosophical Overview

Actuality and potentiality form one of the central conceptual architectures through which philosophy has understood change without dissolving the identity of the changing thing. A young tree grows, an artisan learns a craft, a mineral dissolves, a living being perceives, and a mathematical construction becomes available through an operation. These cases require attention both to what is already there and to what can be realized from it. Their philosophical difficulty lies in explaining how an unrealized determination can be significant for an existing being without being confused with an already existing outcome.

The distinction has two inseparable tasks. It gives an account of becoming by specifying how the same subject can acquire a new determination, and it gives an account of being by explaining how the capacities, organization and form of a thing belong to its present reality. The fragile vessel can be fragile while intact. An experienced pianist remains able to perform while asleep. A seed may possess a structured developmental capacity before a mature plant exists. In each case an actual subject bears a potentiality whose realization is contingent upon an appropriate history of enabling and interfering circumstances. The potentiality is itself an actual feature on many contemporary interpretations, although its manifestation is absent (Martin, 1994; Vetter, 2015).

The classical terms are philosophically more differentiated than their common English counterparts. Aristotle's dynamis (δύναμις) can name a power to act, a susceptibility to undergo change, or a capacity to be in another determinate condition. Energeia (ἐνέργεια) refers to activity or being-at-work; entelecheia (ἐντελέχεια) expresses actuality or completion in a teleological register. Their relations are central to Metaphysics Θ, Physics III, and De Anima II. Translation into the Latin actus and potentia established a durable scholastic vocabulary, but it also carried earlier Greek distinctions into different arguments about creation, causation, essence and existence (Aristotle, Metaphysics Θ.1–9; Aquinas, Summa theologiae I, q. 2, a. 3; I, q. 3).

The investigation has to keep three problems connected while preserving their different logical forms. First, what qualifies something as genuinely able to undergo or produce a change? Second, what is the actuality that a capacity concerns: a completed substance, an ongoing activity, a change in progress, or the possession of another capacity? Third, what makes the passage from capacity to manifestation intelligible? Answers invoke forms, efficient causes, reciprocal processes, necessary conditions, dispositions or modal structures. Their adequacy is tested by cases of interruption, failed realization, multiple possible outcomes and capacities that never manifest.

The historical center of gravity is Aristotle, whose arguments establish the principal distinctions. Yet the problem exceeds Aristotelian natural philosophy. Avicenna makes the contingency of existence a question of explanatory dependence; Aquinas connects act and potency to metaphysical composition; Kant connects actuality with the conditions of possible experience; Hegel reconstructs actuality through essence, possibility and necessity. Contemporary powers metaphysics considers whether properties themselves determine what their bearers can do, while dispositionalist approaches to modality ask whether the possible is grounded in actual capacities. These developments make actuality and potentiality a continuing research problem rather than a closed historical doctrine.

Definition and Conceptual Scope

Actuality, in the primary metaphysical sense, is the determinate being, operation or fulfillment of something under a relevant description. Potentiality is a grounded capacity or aptitude for such a determination, operation or fulfillment. The same subject can be actual under one description and potential under another. A physician currently possesses medical knowledge while being capable of exercising that knowledge in a treatment. The physician's possession of the skill is an actuality of an acquired state, and the exercise of that skill is another actuality. Describing the physician as merely potential without identifying the relevant state obscures rather than explains the relation.

A workable concept of potentiality requires a specification of the bearer, the outcome or operation, and the conditions under which that outcome could occur. The bearer need not possess sufficient power in isolation. Wood can become furniture through skilled work, but its capacity to become a chair does not make the chair an unexpressed object residing in the wood. A developmental potential of an organism depends on inherited structure, environmental support, historical contingencies and the continued integrity of the organism. The modal force of "can" depends on which of these conditions are treated as constitutive and which as external.

Three uses of "possible" must therefore be distinguished. Logical possibility concerns consistency under an interpretation; metaphysical possibility concerns what can obtain given the relevant identities and essences of things; concrete potentiality concerns what particular actual beings are capable of doing or becoming. An internally consistent description of a winged horse is not yet evidence that a given horse possesses the capacity to develop wings. Conversely, the capacity of a material object to break is intelligible without a complete inventory of the possible worlds in which it breaks. Aristotle's own examples restrict potentiality by the relevant subject and conditions (Metaphysics Θ.7, 1048b37–1049a18). Contemporary dispositionalism attempts to understand at least some modality through such actual-world anchors (Vetter, 2015).

The distinction between a capacity and an inclination is also essential. Some capacities are exercisable at will, some are activated through external stimuli, and some are developmental dispositions operating over time. A person can deliberately speak a known language; a glass can shatter when struck; a seed can develop in an environment of appropriate temperature and moisture. Their triggering conditions, degrees of control and modes of manifestation differ. The general term "potentiality" is legitimate only if these differences remain visible.

Nor is actualization identical with appearance. A capability may be manifested through an imperceptible physical transition; a social or legal competence may be exercised through an institutionally recognized act; a cognitive ability may be exercised without an external artifact. The relevant actuality must be established by the ontology of the activity, not inferred from its visibility to an observer.

The question of whether potentialities are real has several possible answers. A dispositional realist treats powers as features of actual objects. A categoricalist may treat the same objects as having an underlying categorical constitution whose lawful relations sustain true dispositional predications. A modal realist can analyze possibilities by reference to a wider plurality of worlds. These accounts disagree over grounding and ontology, but they can agree about which statements of ordinary ability are true. Their disagreement appears when one asks what makes those statements true and whether the explanation is reducible to actual nonmodal facts (Lewis, 1997; Bird, 2007; Vetter, 2015).

Greek Background: Power and Being before Aristotle

The vocabulary of power precedes Aristotle's comprehensive articulation of act and potency. In Plato's Sophist the Eleatic Stranger proposes, within a confrontation between different theories of being, that what has power to act or be affected has a claim to being. At 247d–e the Greek dynamis enters an ontological criterion: something can count as real by virtue of its capacity to enter into an interaction. The discussion continues into objections about intelligible being and knowledge at 248a–e. The dramatic and dialectical setting matters. The proposal tests opposing ontological positions; it should not be extracted as an uncontested formula accepted by every voice in the dialogue (Plato, Sophist 247d–248e).

The philosophical importance of Plato's proposal lies in its movement from a description of isolated objects to the intelligibility of relation. If the reality of a being can be established through its power to affect or be affected, then its being is connected with what it could do under relevant conditions. The proposal opens questions that Aristotle develops more systematically: whether powers constitute a distinct aspect of being, whether the capacity to be affected is as fundamental as the power to produce change, and whether every kind of actuality is an interaction.

The ancient contrast between change and stable intelligibility forms a broader background. Parmenidean reasoning raises the difficulty of becoming something that, in the relevant respect, is not yet. Any theory of generation must avoid deriving determinate being from sheer nothing and must explain why transformation is possible for some substrates and not others. In the Aristotelian reconstruction, matter, form, privation and potentiality permit the specification of an ongoing subject and an intelligible transition. A piece of bronze can be cast into a particular shape; it is not in virtue of bronze alone potentially every logically describable thing.

Aristotle also names the Megarians as opponents of latent ability in Metaphysics Θ.3. In the position he criticizes, a subject has the power to act only while it is acting. His carpenter example reveals the cost: an artisan would lose the craft whenever inactive, although the craft was previously learned and can be employed again. This is a source-specific report of Aristotle's polemical presentation; it does not establish a comprehensive doctrine shared by every historical member of the Megarian school. The argument's continuing force is conceptual. If powers existed only when manifested, powers would do little explanatory work in understanding preparation, interruption, habit or the conditions of future action (Aristotle, Metaphysics Θ.3, 1046b29–1047a29).

These antecedents show why actuality and potentiality arose at the intersection of ontology, agency and explanation. A theory must distinguish possession from exercise, substrate from form and a genuine possibility for this being from an arbitrary alternative imagined by an observer. The subsequent history repeatedly changes the metaphysical basis of these distinctions while preserving their central problems.

Aristotle's Physics: Change as the Actuality of the Potential

In Physics III.1 Aristotle offers his famous definition of motion as the actuality of what exists potentially insofar as it is potential (201a10–11, with the ensuing explanation through 201b). The qualification "insofar as" is decisive. Bronze is actually bronze and potentially a statue; its being cast is the actuality of its relevant potentiality under the description of the material's being transformable. A building material being built is undergoing the operation by which a buildable thing is actualized as buildable. The movement is real and presently ongoing, although the completed structure is not yet present.

This analysis offers a distinctive alternative to conceiving change as either the mere succession of static states or the appearance of a completed form out of nothing. A transition can be actual as a transition. Its subject is already something determinate, its process exhibits an intelligible organization, and its terminal state can remain unrealized. The incompletion of the process belongs to the particular kind of actuality it is. The actual building of a house is not yet a house as completed, but it is not an unreal event awaiting later confirmation.

The definition has attracted criticism because it seems to define motion by invoking the very notion of actuality that motion was expected to clarify. The reply is to distinguish types of actuality and the respects under which they obtain. The actuality at issue is not the final result; it is the progressive realization of a capacity precisely as being realized. One learns through learning, with the active exercise of acquired knowledge emerging at a different logical stage. The distinction between actuality of a process and actuality of a resultant state prevents the definition from collapsing into circularity, although it raises a further problem about whether the distinction is independently intelligible.

Physics III.3 adds a relational thesis: the actuality of mover and moved is, in an important sense, one event described from different sides. The teacher teaches and the learner learns within a coordinated transaction. This does not mean that their capacities or roles are numerically identical. It means that one concrete change can fulfill an active power relative to one agent and a passive potentiality relative to another. Aristotle's account thereby integrates an ontology of powers with an account of causal interaction (Physics III.3, 202a13–202b29).

The generality of this model has limits. An event may involve many interacting causes; a developing organism may sustain its own activity while depending on its surroundings; an artifact may come into existence through several coordinated agents. It is necessary to determine whether a proposed potentiality concerns a particular bearer, a system, or a relational configuration. The Aristotelian framework supplies a question about relevant powers and processes rather than a mechanically sufficient answer for every scientific case.

Metaphysics Θ: Powers, Conditions and the Reality of Capacity

Metaphysics Θ opens by specifying dynamis in the strict sense of a principle of change in another or in the same thing insofar as it is other (Θ.1, 1046a9–19). Aristotle distinguishes capacities to produce changes from susceptibilities to undergo them and treats their relation to actuality as extending beyond locomotion or alteration. The definition locates a power in a structured cause of possible transformation. It also establishes why the passive and active poles of an interaction can be different descriptions of an intelligible capacity relation.

Aristotle separates rational from nonrational powers in Θ.2 and Θ.5. A rational craft can relate to contrary outcomes: medical knowledge can concern health and sickness, although the rational agent's choices and desires affect which outcome occurs. A nonrational power is characterized more narrowly by the outcome it produces under appropriate circumstances. The discussion highlights an often-neglected problem in contemporary accounts: the possession of a capacity does not always determine its exercise, and rational agents introduce deliberation, selection and practical context into the path of realization.

The polemic against the Megarians in Θ.3 establishes that genuine abilities can persist without exercise. This point allows Aristotle to resist the thought that modal truths must collapse into the present inventory of events. Yet Θ.4–5 reject unrestricted potentiality. Capacity has necessary constraints: the outcome must be possible in relation to the bearer and the relevant conditions, and powers operate under suitable combinations of agent, patient and circumstances. A rational capacity additionally involves desire or choice. A mere assertion that something "might happen" does not identify an explanatory power.

The conditions of realization are developed in Θ.7. The statue is possible in the relevant material under circumstances appropriate to the craft, not in any object whatsoever. Aristotle considers obstacles, preparation and the degree to which a substrate is already disposed for the intended transformation. This explains why the phrase "potentially a statue" changes its truth conditions when applied to a shapeless mass, an ingot, prepared metal, or a completed cast. Potentiality has a structure of readiness; the same possible endpoint can be more or less directly realizable from different actual states.

A modern reconstruction can express the relevant claim in relational form: x has a potentiality for M under C at time t if x's constitution at t supports an intelligible route to M under conditions of type C. The formula does not imply that C will occur, nor that all other influences will remain absent, nor that only one outcome belongs to x. It is a disciplined way to separate an ontological feature of the bearer from a prediction of its future.

Aristotle's discussion contains an unresolved tension of enduring interest. He needs a notion of potentiality broad enough to account for the open character of change, yet specific enough to exclude arbitrary results and trivial descriptions. A theory that makes potentialities too narrow becomes a redescription of actual transitions; one that makes them boundless loses its explanatory power. The proper specification of powers and their enabling conditions remains central to the contemporary metaphysics of dispositions (Aristotle, Metaphysics Θ.1–7; McKitrick, 2018).

Energeia, Entelecheia and the Kinds of Actuality

In Metaphysics Θ.6 Aristotle approaches energeia through analogies rather than a single stipulative definition. A waking person is related to one sleeping; seeing is related to possessing sight while the eyes remain closed; formed matter is related to the material from which it was made (1048a25–1048b9). These examples have different ontological structures. Waking and sleeping mark alternating conditions of a living being, seeing is an exercise of an enduring faculty, and the formed artifact is an outcome of a production. Their analogical unity is instructive precisely because actuality cannot be reduced to one of these cases.

An important textual distinction appears in the passage conventionally associated with 1048b18–35, where Aristotle distinguishes activities complete in their occurrence from processes oriented toward a terminus. Seeing is complete as seeing while it occurs; building is directed toward a house that, while construction proceeds, is not yet complete. The grammatical and philosophical contrast between "is seeing" and "has seen" illustrates an activity whose end is present in its exercise. The point is not that seeing is timeless. It is that the achievement proper to seeing is immanent in the act of seeing rather than deferred to a separately produced object.

Entelecheia is often rendered as "actuality" or "fulfillment" and energeia as "activity" or "being-at-work." Translation choices affect the picture of Aristotle. A vocabulary of "actuality" alone risks making every activity look like a static state; a vocabulary of "energy" in the modern physical sense imports an anachronistic scientific quantity. The Greek term does not denote joules or a conserved magnitudinal property. Modern interpretations that speak of being-at-work capture the active dimension while retaining the dependence of individual cases on their primary texts (Aristotle, Metaphysics Θ.6–8; Ross, 1924).

The concepts of completion and fulfillment also need analytical care. They need not imply that all beings are directed toward one predetermined mature form. The kind of completion at issue must be specified by the organized life, practice or process under investigation. A learned skill can be completed as an acquired competence and subsequently exercised in many ways; a manufactured object can be completed while retaining multiple unrealized uses. An actual capacity can be the condition of further potentialities.

The wider result is a layered ontology. A living body is actual as an organized bearer of functions; sight is actual as a possessed faculty; seeing is an actual operation of that faculty; and sensory development may be an actual process through which the faculty is acquired. The duality of actuality and potentiality therefore generates an ordered series of distinct but related descriptions, not a rigid binary dividing the world into completed and incomplete things.

De Anima: Life, Knowledge and First and Second Actuality

De Anima II.1 defines soul as the first actuality of a natural organized body potentially possessing life (412a19–412b6). The argument joins hylomorphism to the classification of life. A living organism is understood through its organized capacities for nutrition, perception, movement or thought, depending upon the kind of organism. Its form is not merely a geometrical arrangement but the principle through which the body has the powers characteristic of its life.

The first actuality of a faculty is distinguished from its second actuality or exercise. A person with knowledge retains knowledge while not presently using it; a person who actually contemplates a problem exercises an already possessed intellectual capacity. The conceptual transition from being able to learn, to having learned, to actively knowing is articulated in De Anima II.5 (417a21–417b16). These distinctions prevent confusion between the general human capacity to acquire a competence, a particular person's acquired competence, and the concrete employment of that competence in a present act.

The model is richer than a conventional distinction between "ability" and "performance." It explains why acquiring knowledge may involve a developmental alteration, whereas exercising established knowledge need not transform the knower in the same sense. Aristotle's point that possessing knowledge becomes knowing in act without ordinary destruction or qualitative replacement gives potentiality a positive relation to maturation and operation. A capacity's manifestation may preserve and perfect its bearer.

The philosophical analysis extends to perception. Sense organs are organized for receiving forms in an appropriate manner; a perceiver can see before the next occurrence of seeing, and seeing occurs through a relation with sensible objects and suitable conditions. The precise Aristotelian theory of perception is contested, but the distinction between dispositional sensitivity and actual perceiving remains widely useful. An account of sensory capability cannot be established only by tallying episodes of experience.

The contemporary significance of first and second actuality appears in theories of competence, skill, habituation and cognitive explanation. A subject may reliably possess a capacity under conditions that prevent its manifestation; a person may lose a capacity while preserving a verbal description of the former performance; and a capacity may require a structured environment for its exercise. These cases show that the ontology of ability must track persistence and change in an underlying bearer. They also expose the limits of inferring enduring competence from a single performance or its absence.

A theory of actuality that reduces all real properties to currently manifest behavior cannot preserve these distinctions without introducing substitutes for latent faculties. Conversely, a theory that attributes capacities indiscriminately without criteria for possession and loss makes competence untestable. Aristotle's layered account encourages both ontological discipline and empirical attention to learning and performance (Aristotle, De Anima II.1, II.5).

The Priority of Actuality: Definition, Time and Substance

Aristotle's claim that actuality is prior to potentiality in Metaphysics Θ.8 is frequently repeated without distinguishing the senses of priority that he explicitly discusses. He argues for priority in account or definition, a qualified temporal priority, and priority in substance or explanatory completion (1049b4–1050b6). Each is an independent argument and requires its own assessment.

Priority in account follows because a capacity is ordinarily specified through what it is a capacity for. The visible is intelligible through seeing; the buildable through building. A disposition cannot be individuated as fragility without some characterization of breaking under relevant conditions. This is a priority of intelligibility, not a claim that the exercise must occur before the disposition exists. The reasoning is strong wherever the outcome helps individuate the capacity, but may be incomplete if powers are identified through reciprocal or systemic relations that cannot be reduced to one isolated manifestation.

Temporal priority is more complicated. For an individual developing entity, potentiality precedes its later fulfillment: the learner before learned mastery, the materials before the finished house. Aristotle's qualification is that relevant actual beings already exist as sources of this potentiality. A human parent precedes the child; an accomplished builder precedes the building. This argument depends on the explanatory organization of reproduction and craft. It is not an unrestricted demonstration that every actual form must historically precede every potentially corresponding form in all conceivable cosmologies.

Priority in substance is grounded partly in final causality. A capacity is acquired or developed for the sake of its exercise or completion; animals have sight in order to see rather than seeing simply in order to possess sight. Actuality gives the explanatory end by reference to which a potentiality is characterized (1050a9–17). In addition, Aristotle connects eternal, imperishable being with a special kind of actuality that excludes the possibility of failing to be. This more demanding theological-metaphysical conclusion must be examined independently of everyday explanations of skills, growth and change.

A central analytical distinction follows: logical or definitional priority, causal priority, temporal priority and ontological dependence are not interchangeable. To say that the concept of fragility is specified by breaking does not imply that an object must break in order to be fragile. To say that a craft is ordered to exercise does not imply that every craftsman must exercise it. To say that one actual bearer explains the acquisition of a capacity does not prove a universal principle requiring eternal actuality.

The merits of the priority thesis are therefore differentiated. The priority of actuality in the account of a determinate capacity is well supported. The priority of actual enabling structures in many natural and technical processes is highly plausible. The stronger thesis of a universal, ultimately pure actuality requires the premises of Aristotle's cosmology and first philosophy. Recognizing this structure allows the distinction to remain philosophically powerful without transforming a historically complex thesis into an unrestricted slogan (Aristotle, Metaphysics Θ.8–9; Λ.6–7).

Pure Actuality and the Aristotelian First Principle

In Metaphysics Λ.6–7 Aristotle argues that a principle whose essence is mere capacity would not guarantee the eternal activity presupposed in his cosmology. If a mover could fail to act, the continuation of motion would remain unaccounted for. His proposed ultimate principle therefore has to be actuality rather than an unexercised capacity. The argument belongs to a cosmological and metaphysical project involving the eternity of motion, the organization of the heavens and the hierarchy of explanatory causes (1071b3–1072b30).

The structure is intelligible even when its astronomical premises are no longer accepted. The explanatory problem concerns whether a series of dependent changes can be accounted for entirely in terms of agents whose efficacy remains merely possible. Aristotle's answer invokes an actuality whose manner of being is fundamentally different from that of ordinary mutable substances. The principle moves as an object of desire and thought, rather than simply transmitting a local physical impact.

There are two different objections. The first challenges the starting assumptions about eternal circular celestial motion. The second challenges the transition from the existence of change to a necessity for an ultimate source that lacks potentiality. A sequence of causal processes might be organized through actual, changing factors without requiring the metaphysical impossibility of any nonmanifestation. Whether such an explanation is complete depends on a separate theory of ultimate explanation.

The philosophical value of Λ lies in clarifying what the strongest form of actuality-priority would entail. If the ground of change itself had to be free of every unrealized potentiality, ultimate explanation would end in a fundamentally changeless act. If the world can instead be explained through irreducibly temporal, relational and processual powers, a different metaphysics becomes possible. The distinction between these options remains a live dispute about explanatory dependence rather than an empirical question settled by any single observation (Aristotle, Metaphysics Λ.6–7; Aquinas, Summa theologiae I, q. 2, a. 3).

Plotinus and the Transformation of Aristotelian Actuality

Plotinus devotes Enneads II.5 [25] to what is potential and actual. The treatise is explicit evidence that the Aristotelian distinction became a major problem inside Neoplatonic metaphysics. Plotinus investigates the applicability of potential and actual being to sensible matter and to intelligible reality, where the relation of form, privation and being differs from the familiar account of physical generation. The doctrinal setting is a hierarchy of the One, Intellect and Soul, rather than Aristotle's explanatory framework alone (Plotinus, Enneads II.5).

The central challenge is whether potentiality necessarily signifies imperfection and dependence on a subsequent actualization. This idea fits many material transformations, yet the intelligible realm is understood as already complete in a manner that complicates a literal transfer of physical change into it. If a being is fully intelligible and unchanging, the question becomes whether its power is a productive perfection or an unactualized lack. The same word "power" can designate the source of effects as well as receptivity to a future form.

The Neoplatonic transformation thus sharpens the difference between active causal power and passive receptivity. A productive principle might possess fecundity without being incomplete in its own being. The metaphysics of emanation cannot be reduced to the simple proposition that a potential entity first waits and then becomes actual. It involves a different relation between plenitude, causal derivation and what follows from a principle.

This distinction has important historical consequences. Later philosophical theology repeatedly asks whether ultimate reality can be said to have power without acquiring new perfection, and whether productive capacity must be identical with realized operation. It is methodologically necessary to compare those arguments at the level of their specific ontological premises, rather than projecting a modern theory of dispositions onto Plotinus's texts.

Avicenna: Possible Essence, Necessary Existence and Causal Dependence

Avicenna's metaphysics reorganizes the relation of possibility to actuality by analyzing the modal status of existence. In the metaphysical section of the Book of Healing, the distinction between what is necessary in itself and what is possible in itself structures an explanation of why contingent beings exist. A being whose essence does not require its own existence depends for its actuality upon a cause; a necessary existent is conceived as requiring no such external explanation (Avicenna, Ilāhiyyāt I.5–7, VIII.1–4; Lizzini, 2026).

This modal structure needs to be differentiated from the Aristotelian capacity of a determinate subject to undergo alteration. For Avicenna the relevant possibility often concerns the existent thing considered with respect to what its essence entails. The essence can be possible in itself, while actual existence is explained through an appropriate cause. This is a theory of causal dependence and existential modality, not simply a theory of a material object's readiness to become another form.

Avicenna's account also generates a distinctive conception of necessity by another. The being that is possible in itself can be necessary through its cause. This explains how an actual contingent being may depend upon causes without becoming necessary in itself. A precise analysis must keep necessity-in-itself, necessity-through-another, possibility-in-itself and actual existence separate. They are not four interchangeable terms for strength of probability.

The transition from possibility to actual existence has explanatory force only if the causal principle and its operation are established. It would be circular to infer the existence of a necessary first cause from the mere definition of a possible entity without defending the relevant causal and explanatory premises. Avicenna's own argument forms part of a sophisticated system involving essence, existence, emanation and the hierarchy of causes. Its validity remains open to scrutiny at each step.

For the history of actuality and potentiality, Avicenna is decisive because the question "what can this being become?" is joined to "what accounts for this being's existence at all?" Scholastic traditions develop both questions while sometimes giving different answers to their interrelation. A monograph that treats every medieval use of potentiality as identical to Aristotle's account of change would miss this central transformation.

Aquinas: Act, Potency, Essence and Existence

Thomas Aquinas places actus and potentia at the center of his analysis of change, finite being and divine simplicity. In Summa theologiae I, q. 2, a. 3, the first way describes motion through the reduction of something from potentiality to actuality by something actual. An object may be actually cold while potentially hot; a suitably actual cause explains a transition in the relevant respect. Aquinas carefully distinguishes actual and potential states under different descriptions, avoiding a contradiction that would arise if the same subject were simultaneously actually and potentially hot in the same respect.

In De ente et essentia, and throughout his metaphysical work, Aquinas also relates essence and existence in finite beings. The act of existing (esse) is not simply the possession of a qualitative determination, and the distinction between essence and esse is metaphysically deeper than the difference between an unbuilt and a built house. What a finite being is does not, on this account, suffice to explain that it exists. Essence can be considered as receptive relative to an act of existence. This applies to immaterial created beings as well as material composites, which means potency cannot be equated with matter alone (Aquinas, De ente et essentia, chs. 4–5; Internet Encyclopedia of Philosophy, "Aquinas: Metaphysics").

The account culminates in divine simplicity. A being conceived as pure act excludes potentiality for further perfection; its existence is not an acquired actuality superadded to an independently existing essence. This theological doctrine links act and potency to several arguments about dependence, causality, simplicity and necessity. Its strength depends on the relevant premises about the composition of finite beings and the explanation of their existence, not merely on an abstract definition of actuality.

Aquinas also distinguishes the capacity to receive a form, the first actuality of having a form, and the second actuality of an operation. These distinctions preserve Aristotle's layered treatment of living and knowing while extending the apparatus to an account of finite existence. The vocabulary is therefore analogical across multiple domains. The act of understanding, the act by which matter receives form and the act of existence cannot be substituted for each other without loss of philosophical precision.

The main objections focus on the explanatory status of essence, the coherence of a wholly simple actuality, and the inference from the actuality of finite causes to a first cause without potency. Contemporary critics may accept the local distinction between a capacity and its exercise while rejecting the further theological conclusions. Such selective acceptance is coherent because the relevant conclusions belong to different levels of argument (Aquinas, Summa theologiae I, qq. 2–3).

Medieval Modal Alternatives: From Potency to Simultaneous Possibility

The medieval history of modality does not follow one continuous line from Aristotle to modern possible-world semantics. Boethius transmits multiple ancient frameworks, including possibility as potency. Twelfth-century and later authors increasingly investigate alternatives that could have obtained at the same time, opening a domain of modal reasoning that exceeds an object's dispositional capacities as specified by its actual nature (Knuuttila, 2021).

John Duns Scotus is especially important for the conception of synchronous alternatives. On the standard scholarly reconstruction, a possibility can be intelligible as non-repugnant to being even where it is never actualized. Possibilities may be mutually incompatible, so a complete inventory of individually possible states cannot be assumed to form one jointly realizable world. Scotus's discussion of divine knowledge and contingent choices develops an account of alternatives to the actual order that differs from the older view that every genuine possibility must be actualized at some time (Scotus, Ordinatio I.35, I.39, as analyzed by Knuuttila, 2021).

This development changes the philosophical question. An actual object can have powers whose manifestation is absent; an unrealized alternative state of the world might be metaphysically possible even where no actual object possesses a direct power to produce it. The difference between a capacity-based and an alternative-based notion of possibility becomes explicit. It is central to contemporary debates between modal dispositionalism and accounts that take modal facts or possible worlds as fundamental.

Scholastic usage of potentiality also remains important for theological questions of divine power and contingency. Yet divine omnipotence, natural capacity and logical consistency should not be treated as interchangeable. A proposition can be logically consistent while lacking a natural route to realization through a particular being; an omnipotence thesis may expand the range of possible interventions without supplying a conventional causal explanation.

The consequence for systematic metaphysics is the need for a layered account of possibility. The history does not warrant replacing potentiality with possibility or possibility with potentiality. It shows why the two became increasingly independent research subjects that nonetheless retain conceptual and historical connections.

Leibniz and the Early Modern Reconstruction of Force

Leibniz's Monadology, composed in 1714, reinterprets the internal principles of created substances in terms of perception, appetite and entelechy. He describes simple substances as having internal principles of change and distinguishes their transitions from merely externally imposed alterations. Sections 11–19 present the vocabulary of perception, appetite and entelechy within a metaphysics of monads, while the larger work develops relations among created substances, their expressive states and the order of the universe (Leibniz, Monadology §§11–19).

The connection with Aristotle is selective. Leibniz does not merely reproduce the hylomorphic account of matter receiving a form. He reconstructs activity as belonging intrinsically to substantial units and integrates change into a rationally ordered world. The capacity of a monad to pass from one perceptual state to another is not a mechanical power caused by the impact of another monad; the whole theory relies on internal development and pre-established harmony. The metaphysical basis of change has shifted.

Leibniz also distinguishes possible worlds and compossibility in his broader metaphysics. The existence of many individually conceivable states does not mean they can coexist in one universe. An actual world is selected from possible arrangements through a theory of sufficient reason and divine choice. This modal account cannot be reduced to the capacity of a single actual object to produce every possible world. It is therefore a historical intersection between theories of active force and theories of global modal alternatives.

The distinction between intrinsic activity and causal interaction has contemporary echoes. Modern powers theorists often regard causal dispositions as real aspects of properties, but disagree over whether their manifestations are internal, relational or jointly produced. Leibniz's system illustrates how a doctrine of activity can be metaphysically robust while committed to a very different picture of causal relations than Aristotle's account of the mover and the moved. The historical comparison identifies shared problems without attributing the same solutions to both thinkers.

Kant: Actuality and Possibility as Modal Categories

Kant's Critique of Pure Reason places possibility–impossibility, existence–nonexistence and necessity–contingency among the categories of modality (A80/B106). Their distinctive function is set out in the Postulates of Empirical Thought in General (A218/B265–A235/B287). Modality does not add a further intrinsic determination to a fully specified concept of an object. Instead it concerns the relation of the object and its determinations to the conditions under which it can be cognized through possible experience (Kant, 1781/1787, A218–A219/B265–B266).

The three postulates differentiate possibility, actuality and necessity. Possibility concerns agreement with the formal conditions of experience; actuality involves connection with its material conditions, especially sensation; necessity depends on a connection with what is actual under universal conditions of experience. Kant's distinction is not simply a restatement of the Aristotelian contrast between a capacity and its exercise. Its critical purpose is to delimit legitimate claims to knowledge of objects in relation to the conditions of experience.

The resulting account challenges two familiar shortcuts. A concept's lack of contradiction cannot by itself establish objective possibility in the relevant transcendental sense, and an object's complete conceptual description cannot establish its actual existence. The proposition that a hundred possible coins have the same conceptual determinations as a hundred actual coins does not eliminate the difference between their possible and actual existence. This theme belongs to Kant's wider criticism of attempts to infer existence from concepts alone.

For the present inquiry, Kant demonstrates that "actuality" has an epistemological as well as an ontological use. A theory may seek what makes a possible being actual in the world, or it may ask how a judgment of actuality is warranted. These questions interact but require different evidence. The claim that a capacity exists may be ontologically meaningful even when empirical access to it depends on experiments, observation and inferential practices.

Kant's analysis also limits the temptation to read the whole modal order directly from imagined concepts. Real possibility must be situated within the conditions that make an object of experience possible. The exact Kantian solution is tied to transcendental idealism, but the problem survives in contemporary modal epistemology: how can our judgments about what could happen be justified without confusing conceivability, causal capacities and actuality?

Hegel: Wirklichkeit, Möglichkeit and Necessity

Hegel's Science of Logic treats actuality (Wirklichkeit) within the Doctrine of Essence, where the relation between inner and outer, possibility and necessity becomes central. The German Wirklichkeit carries implications of efficacy and realization that the ordinary English word "actuality" can obscure. In the section on actuality Hegel reconstructs a progression from formal possibility toward real possibility and necessity, examining the relations of conditions to the actual course of events (Hegel, Science of Logic, Doctrine of Essence, "Actuality").

Formal possibility is comparatively thin. If possibility is understood only as absence of a direct contradiction, it tells us little about the determinate circumstances required for something to occur. Hegel's movement toward real possibility introduces the concrete conditions under which a result belongs to a structured situation. The distinction thus connects modal assessment with the organization of circumstances, causal relations and explanatory dependencies.

Hegel's discussion raises the difficult thesis that when the complete conditions of something are present, that thing enters into actuality. The philosophical significance of this claim depends upon what counts as complete conditions and how necessity is understood. If completeness is defined retrospectively as the circumstances under which an event actually occurred, the thesis risks becoming trivial. If completeness is specified independently, it becomes a substantive claim about determination and causal sufficiency that requires argument.

The dialectical relationship of actuality and possibility should not be translated into a loose maxim that everything imaginable inevitably comes to pass. Hegel distinguishes formal from real possibility and investigates their relations to necessity and contingency. His philosophical procedure seeks to expose inadequacies in abstract determinations by articulating the conditions and relations that those determinations presuppose.

A comparison with Aristotle reveals a shared insistence that potentiality is not an unconstrained realm of bare alternatives. Yet the philosophical architecture differs. Aristotle analyzes powers, substances, ends and their actuality; Hegel reconstructs categories through dialectical relations of essence and existence. The comparison is strongest where it identifies their common demand for determinacy, while recognizing the distinct explanatory structures in which that demand is developed.

Twentieth-Century Reinterpretations: Virtuality and Difference

The twentieth century broadens the actuality–potentiality problem through philosophies that interpret development, creativity and individuation without assuming that every outcome is a preformed version of an antecedent state. In the tradition of Henri Bergson and Gilles Deleuze, the distinction between the possible and the virtual becomes important. An account of creativity must explain novelty while avoiding the illusion that a fully specified future was already waiting, unchanged, to become present.

Deleuze's Difference and Repetition (1968) organizes an ontology of the virtual, differentiation and actualization. The virtual is treated as real, though its mode of reality differs from that of the actual. Actualization is not exhausted by selecting a pre-existing identical model of a finished outcome. The theory's terms of difference, multiplicity and individuation belong to Deleuze's distinctive metaphysical project and are not interchangeable with Aristotle's categories of form and matter (Deleuze, 1968; Stanford Encyclopedia of Philosophy, "Gilles Deleuze").

The crucial analytical issue concerns whether potentiality refers to a determinate power directed toward a known type of manifestation or to a real field of differential relations whose individuated results are generated through a process. The first model offers strong criteria for ascribing capacities to objects. The second promises an account of qualitative novelty in which development can transform the conditions by which its outcome is identified. Their conflict cannot be settled by verbal preference for "creativity" or "completion"; it requires a theory of the continuity and identity of the developing subject.

There is a related epistemic problem. Retrospectively, a realized outcome may appear to have been the only coherent end of the process that produced it. This impression is often an artifact of selecting the successful causal route after the event. A robust philosophy of potentiality has to preserve the explanatory relevance of unsuccessful and unrealized routes where the evidence supports them.

These later interpretations broaden the debate from individual capacities to fields, processes and the emergence of new organizations. They also demonstrate the continuing force of Aristotle's original question: in what respect does an actuality arise from something that was able to become it? A coherent answer may require capacities distributed across a system rather than residing in one preconstituted object.

Contemporary Dispositions: Manifestation without Reduction

Contemporary analytic metaphysics studies dispositions through examples such as fragility, solubility, elasticity, conductivity and learned competences. A familiar conditional analysis states that an object is fragile if it would break when appropriately struck. This captures the relevance of counterfactual manifestation, yet straightforward versions encounter systematic counterexamples. Dispositions may be removed when tested, their manifestation may be masked, and the relevant outcome may be produced by an interfering mechanism rather than the disposition attributed to the object (Martin, 1994; Lewis, 1997; Stanford Encyclopedia of Philosophy, "Dispositions").

A finkish disposition exists before its test but disappears when the stimulus arrives. Suppose a device detects a test for electrical conductivity and instantaneously disconnects the relevant circuit. The object may previously have had the disposition, while the nearest testing situation contains an intervention preventing manifestation. The counterfactual "if tested, it would manifest" can then be false even though the disposition was present. Lewis's improved conditional analysis responds by refining what must remain fixed in the counterfactual evaluation, rather than accepting primitive powers as the only possible response (Lewis, 1997).

Masking differs from finking. Protective packaging can prevent a fragile glass from breaking under a strike while leaving its fragility in place. A mimicker introduces the opposite error: an object lacks the relevant disposition but an extraneous factor produces the outcome normally associated with it. These cases demonstrate that an observed manifestation is neither a necessary nor a sufficient test of disposition possession under arbitrary circumstances. The conditions of testing, masking and mimicry must be specified (Johnston, 1992, as discussed in Stanford Encyclopedia of Philosophy, "Dispositions"; Bird, 1998, as discussed there).

C. B. Martin's influential distinction is that a disposition can be actually possessed despite a nonactual manifestation. This brings the ancient problem into a modern idiom: an unmanifested power need not be an unreal object inhabiting a separate possible realm. It can belong to the current constitution of an actual thing. The metaphysical question is whether such a disposition is primitive, identical with a categorical property, grounded in a causal basis, or constituted by relational features.

A purely behaviorist analysis that identifies possession with episodes of manifestation cannot accommodate fragility between breakings or competence between performances. A purely verbal analysis that labels any nonoccurrence "masked" becomes unfalsifiable. The most fruitful middle position articulates stable criteria for possession, a theory of relevant intervention, and a specification of manifestations sufficient to distinguish the disposition from its competitors.

Powers, Laws and Metaphysical Modality

Modern powers metaphysics asks whether the identity of a property includes what its bearer is disposed to do. Alexander Bird's dispositional essentialism argues that fundamental properties have dispositional essences and that laws of nature can be grounded in those essences (Bird, 2007). On this picture, laws are intelligible through what fundamental properties are, rather than being independent regularities imposed upon otherwise causally indifferent properties.

Stephen Mumford and Rani Lill Anjum develop a dispositional approach to causation in which the production of effects is understood through powers and their interactions (Mumford & Anjum, 2011). The framework directs attention toward tendencies, reciprocal contributions and the possibility of interference. A causal power can be present without producing its characteristic manifestation, because the result depends upon interacting powers and circumstances.

Barbara Vetter's potentiality-based account of modality offers a further development. Instead of treating possible worlds as the basic ontology from which all other modal judgments derive, dispositionalism can attempt to ground metaphysical modality in the potentialities of actual things (Vetter, 2015). This approach faces questions about uninstantiated possibilities, the possibility of wholly different laws or objects, and the scope of potentiality across possible scenarios. Its attraction is to make modal truth answerable to features of the actual world rather than requiring a detached realm of modal entities.

Jennifer McKitrick's dispositional pluralism emphasizes that dispositions are diverse: physical, psychological and other kinds may differ in their manifestation profiles, intrinsic or extrinsic bases and dependence on context (McKitrick, 2018). This diversity is a warning against deriving a single metaphysical formula from an especially simple case such as brittle glass. Capacities may be multi-track, stochastic, relational, acquired or institutionally constituted.

These programs must be compared with a Humean or categoricalist metaphysics. Molnar's study of powers and Mumford's systematic treatment of dispositions sharpen the question of how a property can be directed toward possible manifestations without those manifestations occurring (Molnar, 2006; Mumford, 2003). The Humean may ground dispositional claims in categorical arrangements and laws or regularities; the powers theorist may regard dispositional direction as an irreducible feature of the properties themselves. The disagreement concerns what explains why a thing would behave a certain way if circumstances changed. Both sides can appeal to the same observed experiment, but they interpret the ontological status of the explanatory connection differently (Heil, 2003; Bird, 2007).

A decisive research issue is the relation between property identity and lawfulness. If charge, mass or other properties are identified through their dispositional roles, the laws expressing those roles may have a distinctive modal force. Yet whether scientific theories determine the complete metaphysical essence of such properties remains contested. The transition from successful empirical models to necessary metaphysical identities requires additional argument.

Actualization, Causation and the Problem of Nonmanifestation

The most difficult question is what makes an unrealized capacity become manifest. The language of transition suggests that potentiality itself produces actuality, but the claim becomes uninformative unless a mechanism of realization is specified. A piece of wood does not become a chair because "chair-potentiality" acts as a second artisan. A fragile object breaks through mechanical interactions under relevant forces; a skill is exercised through an organized agent; a legal competence is realized through institutionally constituted procedures. Potentiality explains the eligibility of a bearer for a kind of operation, while causal explanation identifies what brings that operation about.

This distinction resists an illicit inference: from "x can become M" one cannot derive "x will become M." A capacity may persist indefinitely without manifestation, disappear before any opportunity for realization, or be superseded by a different capacity. Aristotle's critique of the Megarians supports the independence of possession from exercise; Martin's modern analysis shows how actual dispositions and unactualized manifestations coexist (Aristotle, Metaphysics Θ.3; Martin, 1994).

The modal relationship can be expressed as a conditional whose antecedent contains suitably qualified conditions. Yet specifying all relevant conditions may involve a difficult choice between an independent scientific description and a clause saying simply that nothing prevents manifestation. The latter is vulnerable to circularity: if an "appropriate condition" is whatever makes the predicted manifestation happen, the claim cannot explain why this particular outcome followed. Useful potentiality attributions therefore need independently identifiable causal bases, triggering circumstances and defeating factors.

Competing powers can produce different outcomes from the same bearer. Water can freeze, evaporate, dissolve substances and drive mechanical work under different arrangements. Some capacities are mutually exclusive in their current exercise but compatible as possessed powers. The actual world is not a catalogue of prewritten individual futures. It contains interacting structures whose dispositions produce histories through contingent sequences of encounters and interventions.

A deeper issue is whether causes necessitate their effects. Some powers metaphysicians treat manifestations as tendencies that need not be deterministic. Other accounts regard the complete relevant conditions as sufficient. The distinction cannot be resolved by treating a capacity as a numerical probability. Probability quantifies outcomes relative to a model; potentiality describes what a bearer can do or become under a specified causal and ontological interpretation. The concepts may interact in statistical science, but one does not replace the other.

Actualization also invites a problem of identity. If a wooden object burns, which thing's potentiality is realized and which thing ceases to exist? If an organism develops through extensive material replacement, what supports the attribution of a persisting capacity to the same organism? A satisfactory theory must individuate subjects across change and determine whether a manifestation belongs to an individual, a system or a transient relation. These are metaphysical commitments, not details supplied automatically by a verbal distinction between potential and actual.

Possibility, Counterfactuals and the Modal Reach of Potentiality

Potentiality should be located within a hierarchy of modal questions. A proposition may be logically consistent, metaphysically possible, compatible with laws, biologically possible for a certain species, practically achievable for an agent, or genuinely realizable by this object in these circumstances. These are different predicates with different grounds. Conflating them leads to false conclusions: that anything logically possible is physically feasible, that every scientific possibility is within an individual agent's power, or that the current exercise of a capacity exhausts its range.

The modal reach of potentiality concerns how far actual capacities can ground claims about nonactual circumstances. If a pane of glass is fragile, it seems correct that it could have broken even though it remained intact. But could an object of an entirely uninstantiated natural kind exist? Could the laws of nature have been different? Could there have been no concrete objects at all? An account grounded solely in the powers of actual objects needs to explain how it handles the absence of the relevant bearers (Vetter, 2015).

Possible-worlds semantics gives systematic truth conditions to modal propositions, but semantics alone does not settle what makes modal facts true. Even if "possibly p" is evaluated by asking whether p holds in some possible world, a further ontological question asks what possible worlds are and how their membership is fixed. Dispositional theories offer a different grounding strategy. The relation between the two need not be a simple rivalry: possible-world models can represent modal structure while potentiality-based metaphysics attempts to account for its ground.

Counterfactuals add a causal dimension. The counterfactual "if the glass had been struck, it would have broken" may fail in masking and finking cases despite genuine fragility. Conversely, a counterfactual outcome may occur through a mimicker. The truth of the counterfactual and the possession of a power therefore diverge. Counterfactual reasoning remains useful only when enriched with causal structure and the relevant stability assumptions (Lewis, 1997).

One promising synthesis distinguishes three explanatory layers: actual bearers and their dispositions, lawful or structural conditions governing manifestations, and formal modal representations of alternative circumstances. A strong account states how the layers relate and where each obtains its explanatory force. It does not assume that one vocabulary can simply replace every other philosophical use of possibility.

Interdisciplinary Horizons: Biology, Physics, Technology and Agency

Developmental biology supplies particularly instructive examples of potentiality. A biological system has capacities shaped by inherited organization, environmental interaction and developmental history. Yet these capacities are often conditional and plastic. The claim that an embryo or organism has a given potentiality must specify the stage, developmental system and relevant conditions. Philosophical inference becomes unstable when developmental facts are represented as a fixed blueprint containing every eventual outcome.

Physical science likewise uses dispositions and state-dependent capacities. Fragility, conductivity, magnetization and phase transitions are explained through material structure and interactions. The classical distinction remains useful for identifying the difference between a standing property and an observed manifestation. It does not authorize the inference that contemporary physics possesses a general measurement called "Aristotelian potentiality." Quantum-theoretic possibilities, for example, involve formal state descriptions and probabilities; their interpretation within an ontology of powers requires an explicit interpretive argument beyond the equations alone.

Technology and design show that potentiality can depend on artifact functions and practical organization. A computer may be physically capable of executing a procedure, but whether that procedure counts as a meaningful task depends on software, interfaces, infrastructure and institutional purposes. The distinction between structural capability, authorized operation and achieved result becomes important. In technical systems, a capability can be actual as an implemented function even when never invoked.

Agency brings a further complication: the bearer of a rational capacity may select among possible acts, and the realization of a skill may be conditioned by reasons, institutions and norms. To explain an action by the agent's ability alone leaves open why it was performed at a particular moment. Actualization may therefore require an account of practical deliberation as well as causal enablement. Aristotle's distinction between rational powers for contrary outcomes remains relevant here (Metaphysics Θ.2, Θ.5).

These cases also clarify the scale of philosophical generalization. The existence of capacities in living and artificial systems invites comparison, but each comparison needs a determinate account of architecture, function, history and evidence. A broader philosophy of the Artificial Era can investigate nonbiological bearers of capacities, yet this research dossier's argument is a general metaphysical one. It establishes concepts through which different orders of existence may be studied; it does not alter the canonical definitions of any particular philosophical system.

Critical Evaluation: Explanatory Gains and Persistent Difficulties

The actuality–potentiality distinction earns its place in metaphysics when it explains something that a record of present events alone leaves obscure. It identifies a persistence condition for capacities, provides a grammar for change, connects material and formal descriptions, and distinguishes an agent's preparedness from its present performance. Its strongest use is explanatory: it tells us why certain outcomes are accessible to some subjects under some conditions.

The first principal objection is indeterminacy. An object may participate in countless possible outcomes under arbitrarily complex circumstances. If every remote result is called one of its potentialities, the notion loses discriminatory force. The response is to individuate a potentiality by the relevant constitution, mode of manifestation and range of sustaining conditions. This response must be principled; otherwise it becomes an ad hoc selection of favorable descriptions.

The second objection is a supposed regress of powers. If every manifestation requires another power to actualize it, an endless explanatory chain appears. Aristotle's answer invokes actual agents and, at the limit, pure actuality. Contemporary alternatives allow a concrete event to be explained through interactions of actual powers and conditions without treating each intervening condition as an additional hidden power. Whether this terminates the deeper metaphysical explanation is a separate dispute.

The third objection concerns teleology. Not every process has a natural goal, and an account of potentiality that interprets all outcomes as the fulfillment of a predetermined end can distort physical, evolutionary and social processes. The response distinguishes teleologically structured capacities, such as the acquisition and exercise of skills, from capacities that are adequately explained through physical powers and conditional interactions. Teleology is a substantive explanatory thesis in the relevant domain, not a definitional consequence of the word "potentiality."

The fourth objection concerns the ontological status of unmanifested powers. A dispositional realist takes them as features of actual things, while a categoricalist seeks to ground them in a non-dispositional basis and an account of laws. The live issue is whether a complete description of the actual categorical constitution plus the relevant lawlike relations supplies the same explanation. No appeal to ordinary ability language by itself settles this metaphysical dispute (Bird, 2007; Heil, 2003).

The fifth objection concerns evidence. If potentialities are never directly visible apart from their manifestations, how can we know them? The answer involves counterfactual reasoning, experimental interventions, structural models and explanatory integration. Evidence for a capacity can include the detection of a causal mechanism or stable organization even when the characteristic outcome is prevented. Yet claims of potentiality can be mistaken, and a sound epistemology must recognize that an anticipated manifestation may fail for reasons unrelated to interference.

These objections show that actuality and potentiality are most rigorous when embedded in an articulated account of identity, causation, laws, conditions and evidence. Their role is to specify a real explanatory relation. Philosophical precision increases as the object, relation and type of actuality are made explicit.

Open Philosophical Questions

The first unresolved question asks whether every metaphysical possibility has a ground in actual reality. A potentiality-based account can explain many ordinary possibilities through powers possessed by actual objects. It faces harder cases involving entirely uninstantiated kinds, alternate laws or a world with no relevant bearers. The answer determines whether modal dispositionalism can be universal or must operate alongside another theory of modality (Vetter, 2015).

A second question concerns the identity of powers. Are powers individuated by their manifestations, their categorical bases, causal roles or a network of reciprocal dispositions? Single-track analyses work well for simple examples, while real properties may have several different manifestation profiles. The relation between a property and its contributions across varying contexts remains difficult (Bird, 2007; McKitrick, 2018).

A third question is whether actualization should be regarded as an ontological transition, a new determination of an existing bearer, or the occurrence of an activity that was already structurally possible. Aristotle's differentiation of movement and complete activity cautions against one indiscriminate answer. Development, skill exercise and physical transformation have different temporal and ontological architectures.

A fourth question concerns indeterminism. If a power can remain unmanifested even when several favorable conditions are present, is its directedness primitive, probabilistic or explainable through further interacting factors? A theory of powers must state what is retained when manifestation fails and what would count as evidence that a power had been misidentified.

A fifth question asks how capacities belong to systems. Many phenomena arise through collective organization and are unavailable to isolated components. Does a system possess an emergent power, or is the system-level attribution reducible to organized powers of parts? Both answers require careful identity and grounding criteria.

A sixth question is normative. Agents possess capacities that support claims about responsibility, education and opportunity, but the possession of an ability does not guarantee fair conditions for its exercise. The philosophical distinction can contribute to an analysis of agency while leaving questions of moral and political evaluation to independent arguments.

These questions provide a defined program for further research. They concern the grounds, individuation, evidence and explanatory reach of powers and their manifestations. They can be investigated without presupposing that the history of the concept determines one final metaphysical doctrine.

Philosophical Synthesis

The inquiry establishes that actuality and potentiality are relational determinations of being that require specified respects. The most basic error in their use is to speak as if actuality named a self-contained class of things and potentiality named a separate class of things waiting to exist. The same actual being can be characterized through realized structure, possessed capacities, ongoing processes and further realizable determinations. What changes across these descriptions is the relation under investigation.

The historical development supports a more exact conceptual architecture. Plato introduces a criterion of being associated with power. Aristotle supplies the central analysis of change, possession, exercise and priority. Plotinus distinguishes receptive potential from productive power within a hierarchical ontology. Avicenna analyzes possibility through the dependence of existence. Aquinas reconstructs act and potency through finite metaphysical composition and the theological idea of pure act. Scotus's modal alternatives reveal a possibility wider than any one current power. Leibniz develops intrinsic activity and compossibility. Kant connects possibility and actuality to the conditions of objective cognition. Hegel reconstructs formal and real possibility in relation to actuality and necessity. Contemporary metaphysics then tests powers through counterfactual failure, masking, causal interaction and the grounding of modality.

The distinctions can be synthesized into four levels. At the level of the bearer, an actual thing has properties and structures. At the level of capacity, those features support determinate ways of acting, undergoing or developing. At the level of manifestation, interactions and circumstances give rise to events, activities or resultant states. At the modal level, philosophical theories ask what makes claims about nonactual manifestations and alternative circumstances true. These levels are connected, but a satisfactory account preserves their different questions.

Actuality's priority in the definition of a determinate capacity remains a powerful thesis: a capacity must be specified by what it enables. Actuality's priority in every possible temporal history or ultimate metaphysical order demands stronger premises. The Aristotelian arguments must therefore be evaluated in their separate senses, and later philosophies should be compared on the level of those distinct arguments.

The systematic conclusion is that potentiality is philosophically informative when it is grounded and individuated; actuality is philosophically informative when it is identified as structure, process, activity or realized outcome; and actualization is philosophically explanatory when its causal and constitutive conditions are made explicit. Neither the fact that a potentiality exists nor the fact that an actuality occurs, taken alone, provides the complete account of their relation.

Conclusion

Actuality and potentiality remain fundamental because the world contains persisting beings whose capacities exceed their current manifestations and because change has a structure that cannot be captured by an inventory of completed outcomes alone. The concepts articulate the relation among being, agency, transformation, causation and modal truth.

The historical reconstruction demonstrates that the same conceptual pair has served several different inquiries. Aristotle explains change and the organization of living substances, medieval philosophers analyze the dependence and necessity of finite existence, Kant determines the use of modal concepts in experience, Hegel investigates the relation of possibility and actuality within the logic of essence, and contemporary metaphysicians study the reality of unmanifested powers and their role in laws and modality. These investigations share a central problem while providing distinct ontological and epistemological answers.

The principal result is an account of potentiality as a grounded, bearer-relative and condition-sensitive capacity and of actuality as a determinate state, operation or process. The reality of a capacity is compatible with the indefinite absence of its manifestation. Its explanatory value derives from the specificity of what its bearer can do or become and from the identifiable conditions of realization. An adequate theory must therefore distinguish actual possession, possible manifestation, causal realization and the wider scope of metaphysical possibility.

The remaining work concerns the metaphysical grounding of modal truths, the individuation of powers, the role of indeterministic causation, and the distribution of capacities across complex systems. The actuality–potentiality distinction provides a rigorous framework for pursuing those questions, provided its historical meanings are preserved and its contemporary applications are argued rather than assumed.