A summary of Mackie, Penelope. “Mumford and Anjum on incompatibilism, powers, and determinism.” Analysis 74.4 (2014): 593 – 603. A reply to Mumford and Anjum (2014). Recovered from an old comment I’ve posted elsewhere.
Recall the core argument in Mumford and Anjum (2014):
- If causal determinism obtains, then all events are necessitated.
- If all events are necessitated, then there are no powers.
- Free will consists in the exercise of an agent’s powers.
Therefore, if causal determinism obtains, then there is no free will.
Mackie focuses her attention on the defense of (2) from the “Possibility of Interference,” arguing that not only do Mumford and Anjum fail to adequately defend (2), but in addition that what they say elsewhere seems to incompatible with it. Recall that Mumford and Anjum object to (2) on the grounds of their account of dispositional modality, which rests between strict necessity and pure contingency, to the effect that causes themselves never necessitate their effects, an argument they tie to the ever-present possibility of interference, as discussed above. Mackie is puzzled by this move from the possibility of interference to the incompatibility of necessitation with powers, since they allow elsewhere for a result to be necessitated even if not by its causes simpliciter – in effect, they seemed to accept before that causal determinism and powers were compatible. It’s worth quoting both passages Mackie cites here, in full:
Dispositionality is thus never a source of the necessity of something in the world, even if it exists alongside it. In the deterministic case, for instance, where it is necessary that Fa, that is not because there was a disposition towards it. What delivers the necessity in claim B is that, somehow, everything got fixed. That will include the fixedness of all the background conditions –including which dispositions do, and which do not, act to produce the necessitated outcome – but it was not those powers that necessitated that outcome.
Mumford, Stephen and Rani Lill Anjum. Getting Causes from Powers. Oxford: OUP, 2011. pp. 178-179.
Given what has been said about B, therefore, claim D should not be read as saying that necessity and dispositionality are incompatible absolutely. Rather, it needs to be read as disposing towards F is never the necessitating of F, even if F is for some other reason, necessitated.
Mumford, Stephen and Rani Lill Anjum. Getting Causes from Powers. Oxford: OUP, 2011. p. 179.
(For background context, these citations come from chapter 8, where Mumford and Anjum develop their account of dispositional modality. Claim B is that if a has a disposition to F, then it is non-necessary that a F’s and D is the contrapositive, such that if it is necessary that a F’s, then a does not have a disposition to F)
Is there then a reason to hold that a powers-based view of causation cannot accommodate causal determinism – that is, to uphold (2)?