- Dispositions are as shameful in many eyes as pregnant spinsters used to be – ideally to be explained away, or entitled by a shotgun wedding to take the name of some decently real categorical property. It is time to remove this lingering Victorian prejudice. Dispositions, like unmarried mothers, can manage on their own. They have been traduced, and my object here is to restore their good name.
- Raising the status of dispositions matters more than might at first appear. It matters to the propensity theory of chance, which takes the half-life of a radium atom and the increased physiological age of a heavy smoker to be dispositions. It matters to the theory that beliefs and other mental states are dispositions. But it is more politic to argue from the usual paradigms than from such complex and controversial examples.
- My strategy will be to show the offending features of dispositions to be either mythical or common to other properties of things; just as loose living is no prerogative of the unmarried and so is no proper basis for discriminating against them. I shall put my case in terms of dispositions being "real" properties. Nominalists will have to rephrase it (in terms of the intelligible application of dispositional predicates not requiring them to be coextensive with non-dispositional predicates). Nominalism is not the issue here, as Goodman observes1; my realist terminology begs no relevant questions.
- What then is the force of saying that dispositions are real properties? Take its shape as an archetypally real (and prima facie non-dispositional) property of a thing. To call a piece of cardboard "triangular" seems clearly to say how it is in itself, not merely how it is disposed to behave in this or that situation. (We shall see in the end that this distinction has no force; but let it stand for now.) No one doubts that a triangular thing thereby differs substantially from anything that is not triangular. No one would doubt that a piece of rubber which is triangular at time t1 and not at time t2 must in the meantime have changed in some way admitting of causal explanation.
- Just so, I say it follows that if just one of two seemingly identical glasses is fragile, there is a substantial difference between them – apart, of course, from their numerical and spatiotemporal differences (a proviso I take as read hereafter). It follows likewise, if a glass is fragile at t1 and not at t2, that an event has occurred meanwhile which could have had causes and may have effects.
- These claims are commonsensical enough to throw the onus of proof on whoever denies them. They would not need arguing for had they not been argued against. But they have been argued against, and these arguments have not, to my mind, been sufficiently met. So I shall have in what follows to criticize some allied, as well as some opposed, literature.
Footnote 1: "Goodman (Nelson) - Fact, Fiction and Forecast", 1965, p. 42.
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