Dispositional Properties

[PJ Moriarty]

Hi, folks. I figured I would start my first serious topic on my favorite pet issue; causal powers.

I'm wondering about the opinions of members here on the existence of dispositional properties. Dispositions are difficult to define precisely. They are properties that have the ability to be manifest in some entity, such that if P happens, Q follows. Solubility is a paradigm case. A sodium ion is soluble in a body of water. There is not a constant action of "Soluble" in a sodium ion. The properties that are manifest always, such as shape, size, location are known as categorical properties.

The big question in this area of metaphysics is which property is ultimately efficacious in the explananda? Many philosophers, in large part the Australian physicalists and neo-Humeans grant the role of ultimate explanation to categorical properties. Dispositions are the result of these categorical properties and therefore any explanation in terms of dispositions can be reduced to explanation by the categorical properties.

There is another school of thought, which is much more vast and diverse, that says at least some dispositions exist independent of categorical bases. They are essential in explanation of phenomena. Some in this camp think there exists a dualism and others are monists, saying that dispositions are the only fundamental properties.

My personal convictions lay with the latter and I think there is good reason for Objectivists to accept this school of thought over the categorical realists. As noted briefly before, these are mostly neo-Humeans, who do not think there are necessary connections in the world. All causal relations perceived are at best contingent. In some possible world away from our own, a rubber ball may be thrown at a wall and instead of bouncing will simply mesh with the wall, because there is no necessary connection between certain amounts of rubber and solid, firm surfaces.

The dispositional realist admits into their ontology at least some legitimate causal powers. This leads to a necessitarian view of laws of nature. The laws in this universe are necessary, not contingent truths. How could we have the same causal powers and different results when the causal powers are standalone properties?

Even though I'm convinced of the truth of dispositional realism/essentialism myself, Rand had something to say on the subject, towards the end of the Q&A. She seems to agree, at least to some degree, with those in the categorical camp. She criticizes the distinction between categorical and dispositional properties. This leaves her open to folks such as Alexander Bird, who think there there is no dichotomy and that dispositions are the fundamental properties of all objects. Still, she seems in the short discussion to side with reduction of dispositions.

SEoP has a good article on this topic. I would also suggest, if you are so inclined, to check out the works of Brian Ellis and Alexander Bird.

http://plato.stanford.edu/entries/dispositions/