The metaphysics of dispositions

Abstract

As Nelson Goodman put it, things are full of threats and promises. A fragile glass, for example, is prone to shatter when struck. Fragility is the glass's disposition, shattering is the manifestation of the disposition, and striking is the circumstances of manifestation. The properties of a fragile glass which are causally efficacious for shattering constitute the causal basis of the glass's fragility. The glass can remain fragile even if it never shatters. One can say of the fragile glass, with certain qualifications, that if it were struck, it would shatter. This much is common ground among philosophers who discuss dispositions. In my dissertation, I defend three claims about dispositions that are more controversial. Some philosophers have claimed that dispositions are causally impotent. I disagree. In my first chapter, I defend the claim that dispositions can be causally efficacious with respect to their manifestations. Among the arguments I consider is the "no work" argument, according to which a disposition's causal basis causally explains its manifestation, leaving no causal work for the disposition to do. I respond to this argument by challenging the Principle of Explanatory Exclusion, according to which complete explanations exclude competitors. Furthermore, many philosophers hold that all dispositions must have independent causal bases. In my second chapter, I challenge this view, and defend the possibility of bare dispositions. I argue that the concept of a bare disposition is coherent, and show why arguments recently offered against bare dispositions, such as those based on the Truth Maker Principle, do not succeed in demonstrating that they are impossible. Another common assumption about dispositions is that they must be intrinsic properties of the objects that have them. In my third chapter, I challenge this assumption, and argue that some dispositions are extrinsic properties. Consider the property vulnerability. It seems dispositional in character; something which is vulnerable is susceptible to harm, but is not necessarily being harmed right now. However, it seems as if something could lose the property of being vulnerable without undergoing any intrinsic change. Build a fortress around the vulnerable object and it ceases to be vulnerable.