Essential versus Accidental Dispositions in the Four-Category Ontology

 E. J. Lowe

There is an intimate connection between the dispositions that we attribute to continuant objects and the kinds that we classify them under. As Locke put it, ‘Powers make a great part of our complex Ideas of Substances’ (Essay, II, XXIII, 8). Currently, the most popular type of analysis of disposition-attributions is still the conditional one, framed in terms of stimulus/manifestation pairs. But this type of analysis fails to reflect Locke’s important insight and is also defective for other well-known reasons, highlighted by C. B. Martin. The four-category ontology contains the resources with which to analyse disposition-attributions in a quite different way — one which does do justice to Locke’s insight. According to this analysis, we may say, at least to a first approximation, that an individual object a has a disposition to F just in case there is some substantial kind, ϕ, such a instantiates ϕ and the attribute F characterizes ϕ. For details, see E. J. Lowe, The Four-Category Ontology: A Metaphysical Foundation for Natural Science (Oxford University Press, 2006), where the four categories of the system — objects, kinds, attributes, and modes — are also fully explained. However, this type of analysis has been attacked on the grounds that it allegedly fails to allow for the fact that different objects of the same kind need not all possess the same dispositions. In this paper, it will be shown how this objection may be overcome, by distinguishing between essential dispositions (which are indeed shared by all objects of the same kind) and accidental dispositions (which need not be).