Wednesday, September 1, 2010

Powers and impossibility

One might think that powers necessarily involve some relation to the activities for which they are powers. After all, we do not say that 'Jane has the power' without stating (or at least implying) what Jane has the power for. Thus, it would seem that a connection with the relevant sort of activity is built into the very nature of a power.

Still, I wonder what that actually means, ontologically speaking. One theory would be this: something has the power to do an activity if it is possible for it do that sort of activity. And if that were the case, then something x would have the power to perform an activity A if there were some world W where x (or a sufficiently similar counterpart of x) actually performs A.

I don't know if I buy this particular view, but it seems to me rather intuitive. After all, if there were no worlds at all where x performs A, then it would be impossible that x performs A. That's just the definition of 'possible' and 'impossible': something is possible if it happens in some world, and it is impossible if it happens in no world. So also here: if x does A in some world, then it's possible, but if x doesn't do A in any world, then it's impossible. And if it's impossible, then surely x does not have the power to perform A, plain and simple.

On this view, one could say that a power (or at least a type of power) is essentially connected to its corresponding activity, for there will always be at least one world where the agent actually performs the activity in question.


Scott Williams said...

By using possible-world semantics, are you suggesting the following. x is a person, P is x's power to cry. W1 is a world in which x cries. W2 is a world in which x does not cry.

So on this view, is x's P in W1 a real relation to the activity _crying_, but x's P in W2 is not a real relation to the activity _crying_?

It seems problematic to say that P is a real relation (in W1), and not a real relation (in W2). Which is it, on this view? But I take it that this problematic entailment arises by assuming some metaphysics in possible-world _semantics_.

JT Paasch said...

I don't think I'm suggesting that. It seems to me like an odd way of thinking about the issue. Recast your point in terms of possibility (since I'm proposing that powers are nothing more than possibilities): let x be a person, and let P be the possibility that x can trip. Let W1 be a world in which x trips, and let W2 be a world in which x does not trip. Is this P of x a real relation to the activity of tripping in W1, but not in W2?

But in any case, the relationship I'm talking about here is just the possibility relationship. Like when we say, "It's possible that I get elected President." That just means I get elected president in some world, but not in other worlds. Likewise for powers. "I have the power to shoot fire from my hands" just means I shoot fire from my hands in some world, but not in other worlds.