Sunday, 18 December 2016

My future self or myself in the future

In discussing issues such as, for example, whether prudential reasons can be accounted for in terms of desire based reasons, we sometimes contrast our present self with our future self. It's possible that some arguments turn on whether my present and future selves are distinct or whether talk of these selves is just a misleading way of speaking of me now and in the future. 4 dimensionalism (4D) accounts for persistence through time in terms of temporal parts, and if it is true then my future self is not identical to my present self, but both are temporal parts of me, whilst I am a space time worm that is the fusion of all my temporal parts (for short, a maximal space time worm). Jim Stone has recently offered a refutation of 4D in Analysis. Here is my condensed version of his argument:
1.      Suppose, for a contradiction, that 4D is true
2.      Fred has the thought 'I am a maximal space time worm'.
3.      Under 4D,  objects persist through time by having temporal parts
4.      What it is for a person to have a thought is for a temporal part of the person to have that thought.
5.      So Fred has a temporal part, Fredlet, which thinks the thought.
6.      The thought had by Fred is the same thought as that had by Fredlet.
7.      Persons are maximal space time worms and temporal parts of persons are not.
8.      So Fred's thought is true whilst Fredlet's thought is false.
9.      So the same thought is both true and false.
10.  Therefore 4d is false (1, 9, by contradiction)

It’s a great argument, but I have to wonder whether so much can be achieved by so little. Could the nature of having thoughts alone really entail that 4D is false? We can evade the conclusion by taking the contradiction to apply to other premisses or to presuppositions of those premisses. These look to me like the main options:

A)                Deny 2. But there have been philosophers who believed this of themselves.
B)                 More radically, Robin Hanson suggests denying that people have thoughts at all but that only temporal parts do. This seems to me to be worse than denying 4D. Unlike 4D, that people have thoughts is a good candidate for a Moorean fact (something of which we are more certain than the premisses of any philosophical argument we possess to the contrary). Also, on some accounts of temporal parts the argument could still be run for parts of parts.
C)                Deny that the indexical 'I' refers to anything but Fred, even when used in the thought of Fredlet. But can an indexical work like this? Jim Stone argues no.
D)                Deny 4 by denying that temporal parts have thoughts. Fred has thoughts by something or other going on in Fredlet, but whatever it is, its not a thought. This would not appear to be a comfortable resting place. On the other hand, if we think that the nature of thought alone couldn’t entail the falsehood of 4D, we might yet expect that the nature of 4D could place some constraints on the nature of thought.

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