Metaphysics

Metaphysics is the branch of philosophy concerned with the most general features of reality. At its core lies ontology, the study of what exists and how entities relate, and includes enquiries into substance, properties, causation, identity, change, time and space. The metaphysician asks whether the world is fundamentally one or many, whether its ultimate constituents are physical or conceptual, and what modal status—possible, actual or necessary—attaches to those constituents. Classical debates contrasted realism, which holds that categories such as “causation” or “natural kinds” track mind-independent structures, with anti-realist or nominalist accounts that treat such categories as constructs of language or thought. Modern metaphysics has diversified into topics such as the metaphysics of mind and consciousness, the metaphysics of science (including the ontology of fundamental physics), the metaphysics of modality and emergence, and the metaphysics of value. Current research draws on historical insights (from Aristotle’s doctrines of being qua being, through medieval perspectives on substance and universals, to early modern conceptions of modality) and seeks to clarify the conceptual foundations of contemporary science and everyday discourse. Methodologically, the field balances rigorous conceptual analysis—often deploying formal tools such as modal logic or category theory—with sensitivity to empirical findings, for example in physics or the cognitive sciences. Far from an arcane discipline, metaphysics underpins ontological frameworks in information technology, informs philosophical approaches in biology and chemistry, shapes debates about artificial intelligence and consciousness, and contributes to the conceptual clarity required in ethics, law and social policy.

Research from Nature Portfolio

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Research from all publishers

Two recent theoretical studies have deepened the division between the philosophy of language and the philosophy of science approaches to natural kinds. One analysis argues that efforts to unify these approaches are bound to fail, recommending that we treat “linguistic” and “scientific” kinds as distinct categories, each serving its own explanatory purposes. Experimental work has tested whether speakers treat novel substances as members of a familiar kind on the basis of superficial likeness or underlying essence. The results favour essence-based judgements, reinforcing the view that our kind concepts track real microstructural properties. More technical discussion has revived and defended the pure causal-historical theory of reference. According to this view, a natural kind term secures reference by causal links to a super-explanatory property that grounds both the term’s meaning and its inductive potential. Finally, debates over mind-independence have been recast in terms of unification principles: only those categories whose unity rests on objective causal or structural principles qualify as genuine natural kinds, a move that promises to bridge metaphysical theory and scientific practice.

Metaphysics publication trend

The graph below shows the total number of articles in metaphysics across all publications each year (not limited to Nature Index journals).

Technical terms

Ontology: The study of what exists and the most general categories of being.

Substance: An entity that exists in itself and serves as the subject of properties.

Universals: Abstract features (such as redness or causation) that can be instantiated by many particular entities.

Modality: The study of possibility and necessity, often formalised in terms of possible worlds.

Natural kind: A category whose members share intrinsic properties that support reliable scientific inference.

References

1. Two approaches to natural kinds. Synthese (2021).
2. Are Natural Kind Terms Ambiguous?. Cognitive Science (2023).
3. Natural kinds, mind-independence, and unification principles. Synthese (2022).