General · EdgepediaSeptember 17, 20268 min read

Metaphysics

Metaphysics is the branch of philosophy concerned with the most general features of reality: what exists, what those things are like, and what categories, such as substance, property, causation, identity, and modality, structure them. Its core subfield is ontology, the study of what exists and how entities relate.¹ The word is notoriously hard to define, because the field's scope has changed repeatedly since antiquity.²

Key fact	Detail
Etymology	From the title Ta meta ta phusika ("the ones after the physicals"), given to fourteen books of Aristotle at least a century after his death, probably by the editor Andronicus of Rhodes²
Aristotle's names for the field	"First philosophy", "first science", "wisdom", and "theology"²
Traditional subject matter	"Being as such", the first causes of things, and things that do not change²
Seventeenth-century shift	Problems such as mind and body, free will, and personal identity across time were reassigned from physics to metaphysics, and the word "ontology" was invented around that time²
Wolff's division	Christian Wolff distinguished general metaphysics (ontology) from special metaphysics, which studies the being of particular kinds of objects such as souls and material bodies²
Kant's challenge	The Critique of Pure Reason asks whether reason can achieve a priori knowledge independently of all experience, and Kant argues it cannot reach the supersensible realm of speculative metaphysics³^•⁴
Contemporary topics	Metaphysics of mind and consciousness, metaphysics of science, modality and emergence, and metaphysics of value¹

The word and its origin

The word "metaphysics" does not mean "beyond physics" in the sense suggested by twentieth-century coinages like "metalanguage" and "metaphilosophy". It comes from a collective title given to the fourteen books of Aristotle that make up the work now called his Metaphysics. Aristotle himself did not know the word; he called the field "first philosophy", "first science", "wisdom", or "theology". At least a hundred years after his death, an editor of his works, in all probability Andronicus of Rhodes, titled the books Ta meta ta phusika, "the ones after the physical ones", the physical ones being the books of the Physics. The title probably indicated the place the topics were meant to occupy in the curriculum: they were to be studied after the treatises on nature, that is, on change.²^•⁵

The Greek plural phrase became in Medieval Latin the singular noun metaphysica, much as the Greek plural ta biblia ("the books") became the Latin singular biblia. It served both as the title of Aristotle's book and as the name of the science that was its subject matter, and every modern European word for metaphysics adapts the Latin term.⁶

The traditional subject matter

Ancient and Medieval philosophers could define metaphysics by its subject matter: the science that studied "being as such", or "the first causes of things", or "things that do not change". Aristotle identifies the subject of first philosophy as "being as such" in one place and as "first causes" in another; a vexed question is how these definitions connect. One suggested answer is that the unchanging first causes have nothing but being in common with the mutable things they cause.² In Book IV of the Metaphysics, Aristotle argues that there is a single science investigating being qua being, and that the philosopher, as the student of reality as a whole, must also investigate the axioms of reasoning, such as the principle of non-contradiction.⁷

This definition no longer works, for two reasons. First, a philosopher who denies the existence of first causes or unchanging things is now considered to be making a metaphysical assertion, so denial belongs to the field as much as affirmation. Second, many problems now counted as metaphysical, such as free will or the relation of the mental and the physical, have no connection to first causes or unchanging things.²

Expansion and reorganization

In the seventeenth century, topics that Aristotle and the Medievals would have classified as physics, including the relation of mind and body, the freedom of the will, and personal identity across time, began to be reassigned to metaphysics, which became something like a catch-all category for philosophical problems not otherwise classified as epistemology, logic, or ethics. Around the same time the word "ontology" was invented, to name the science of being as such, an office the word "metaphysics" could no longer fill alone.²

Wolff's system. The post-Leibnizian rationalist Christian Wolff tried to justify the broader usage by distinguishing "general metaphysics" (ontology), the study of being as such, from the branches of "special metaphysics", which study the being of particular kinds of objects, such as souls and material bodies. He assigned the study of first causes to natural theology, a branch of special metaphysics. Commentators question whether this is more than a verbal ploy, since rational psychologists, for example, rarely said anything that plausibly contributed to understanding being as such.² A possible cause of the widening was that "physics" was becoming the name of a new quantitative science, increasingly inapplicable to traditional philosophical problems about changing things.²

Kant's critique

The main topic of Kant's Critique of Pure Reason (1781, 1787) is the possibility of metaphysics, which Kant defines in terms of "the cognitions after which reason might strive independently of all experience". His goal is a decision about the possibility or impossibility of metaphysics in general, and the determination of its sources, extent, and boundaries, from principles.³ In the Transcendental Dialectic he argues against the Leibniz-Wolffian view that human beings can achieve a priori knowledge in the domains of rational psychology, rational cosmology, and rational theology, attributing the errors of that metaphysics to an illusion rooted in the nature of reason itself.³ On this account it is impossible to extend knowledge to the supersensible realm of speculative metaphysics.⁴ Kant nonetheless held that reason's principles play a necessary regulative role in science, a critical reinterpretation of the rationalist ideal of complete knowledge.⁸

Contemporary metaphysics

On a traditional conception, still endorsed by philosophers such as David Lewis, metaphysics aims to answer two questions in a fully general way: what is there, and what is it like? Lewis treated this as an unproblematically factual inquiry into the nature of reality, not mere analysis of our conceptual scheme.⁹ Contemporary research has branched into fields such as the study of mind and consciousness, of science (spanning the ontology of fundamental physics), of modality and emergence, and of value, while it also draws on historical insights ranging from Aristotle to medieval and early modern conceptions of modality.¹

Grounding. A prominent recent development treats metaphysics as centered on grounding, a form of constitutive (as opposed to causal or probabilistic) determination or explanation. Jonathan Schaffer writes that "metaphysics as I understand it is about what grounds what" rather than what exists, and Kit Fine holds that questions of ground are central to realist metaphysics, remarking that if considerations of ground were abolished, very little of the subject would remain.¹⁰

Metaphysics and science. The relation between the two remains a live methodological question. Ladyman and Ross argue that non-naturalistic metaphysics, which draws heavily on intuitions and common sense, should be discontinued, and that metaphysics makes progress in lockstep with science only to the extent it is closely motivated by science.¹¹ Naturalized metaphysics proceeds only by means of scientific results and scientific methods, while the program of inductive metaphysics is less restrictive, allowing a priori and abductive methods alongside empirical sources.¹² Critics of autonomous metaphysics argue that its traditional methods, a priori reasoning, conceptual analysis, intuitions, and common sense, are unsuited for justifying conclusions about ultimate reality.¹¹

Experimental approaches. The experimental philosophy movement applies empirical methods, mainly surveys, to traditional philosophical debates, with a positive program that treats folk concepts as inputs to theorizing and a negative program that argues intuitions are unreliable.¹³ Its application to first-order metaphysical questions is recent; a separate tradition, named "experimental metaphysics" by the philosopher and physicist Abner Shimony, studies how Bell-type quantum experiments bear on questions of reality and locality raised since the Einstein-Podolsky-Rosen argument.¹⁴

Debates about the field's value

Global critiques of metaphysics have a long history, including those of Hume, Kant, Wittgenstein, and the logical positivists of the early twentieth century; later work, beginning with Carnap's "Empiricism, Semantics, and Ontology" (1950), has mostly pursued local critiques of specific metaphysical questions, such as whether disputes about composite objects are merely verbal or lack a fact of the matter. These second-order disputes are often characterized as metametaphysics or metaontology.¹⁵ Recent work frames the value debate through the notion of progress: critics press a "Progress Worry" that metaphysics does not make enough progress, while defenders note that only one account of progress takes justification to be necessary, so the alleged lack of justification in metaphysics does not by itself entail lack of progress.¹¹

References

Topic: Encyclopedia › Physical world and mathematics › General science and scientific practice › Philosophy of science

Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Sep 30, 2026; Oct 15, 2026 · Last review: Oct 15, 2026

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