Dispositional Properties

Core Idea

Dispositional properties are defined by their tendency to cause effects in certain conditions. Fragility is a disposition to break when struck; solubility is the disposition to dissolve when placed in a solvent. Some philosophers argue that all fundamental properties are ultimately dispositional.

Explainer

From your study of the categorical-dispositions distinction, you know that properties can be sorted into two broad types. Categorical properties describe how something actually is at a moment—shape, size, mass, spatial arrangement. Dispositional properties describe how something would behave under certain conditions—its tendencies, powers, and susceptibilities. Fragility, solubility, magnetism, and flammability are paradigm cases: a glass is fragile right now even if it is never struck, because fragility is the property of being such that it would break if struck. Dispositional properties point beyond the present moment toward possible interventions and their outcomes.

The standard philosophical analysis of dispositions uses counterfactual conditionals: to say X is fragile is to say "if X were struck with sufficient force, X would break." This conditional analysis is appealingly simple—it seems to reduce dispositional talk to talk about what would happen under hypothetical circumstances. But the analysis runs into difficulties. Consider a finkish disposition: a glass that is normally fragile but is protected by a wizard who would, the instant it was struck, make it invulnerable. The glass satisfies the counterfactual ("if struck, it would break") as stated—except that the wizard would intervene. So the glass is not actually fragile, but the conditional comes out true. Conversely, a glass might be intrinsically fragile but protected by a force field, so "if struck, it would break" is false (the force field would prevent striking from occurring), yet we still want to say it is fragile. These masking and finking cases show that simple counterfactual conditionals do not fully capture dispositionality.

This leads to a deeper metaphysical question: what is it in virtue of which an object has its dispositions? One view—categorical reductionism—holds that dispositions are grounded in categorical properties. A vase is fragile because of its molecular structure, its crystalline lattice arrangement, its chemical bonding—all categorical facts about its current state. The disposition is real, but it is nothing over and above the categorical base. An opposing view—dispositional essentialism—holds that at the fundamental level, properties just are dispositions. The charge of an electron is not first a categorical property that happens to confer certain dispositions; the charge is the disposition to repel other negative charges, to attract positive ones, to affect electromagnetic fields. On this view, the categorical/dispositional distinction may ultimately dissolve at the fundamental level: everything reduces to powers and their mutual relations.

The stakes of this debate extend into causation, laws of nature, and science. If fundamental properties are dispositional—if they are essentially powers—then laws of nature are not external constraints imposed on otherwise inert properties, but fall out of what the properties are. Nature is driven by its own internal structure of powers and their manifestations. This "powers" metaphysics, associated with philosophers like Sydney Shoemaker and Brian Ellis, offers a picture of a world that is dynamically self-organizing rather than passively governed by contingent laws. Understanding dispositional properties is thus a gateway into some of the deepest questions about what makes the physical world tick.