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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.


  1. 1. Posted by Robin Hanson | June 18, 2007 2:09 pm

    To clarify, human language is often sloppy about attributing to a whole properties that strictly speaking only apply to elements or parts of that whole. We might say “the car has a flat” when we mean “the car has a tire with a flat” or we might say “happy home” when we mean “a home with happy people.” So the fact that we are in the habit of saying “people have thoughts” could be understood as similarly sloppy talk.

  2. 2. Posted by S. Matthew Liao | June 19, 2007 2:20 am


    On the view that only temporal parts have thoughts, Shackel/Stone would, I think, respond that Fredlet would be thinking falsely, when he thinks ‘I am a maximal space time worm.’ But, so the argument would go, this thought seems to be true. Therefore, there is something wrong with the view that only temporal parts have thoughts.

    However, there are two possible moves that advocates of 4D, especially those who combine the worm view with counterpart theory (WC), could make in response. On WC, Fredlet would exist at a particular time (t); at other times (~t), only Fredlet’s counterparts would exist, if at all. So, advocates of WC could either argue that the thought ‘I am a maximal space time worm’ is actually false, if by ‘maximal space time worm,’ one means that ‘Fredlet exists at ~t.’ Or, they could argue that Fredlet is in fact thinking truly when he thinks ‘I am a maximal space time worm,’ because on a proper WC interpretation of this thought, Fredlet would be thinking that ‘Fredlet exists at t and Fredlet’s counterparts exist at ~t,’ when Fredlet is thinking this thought, which seems to be true.

  3. 3. Posted by Nick Shackel | June 20, 2007 1:17 am

    Robin: I’m not really seeing how your clarification addresses the Moorean fact claim. Saying that people have thoughts is a part of a highly developed psychological discourse of attributing mental states to persons, all of which you are going to have to say is mistaken. Furthermore, as I suggested, the argument can be run for parts of parts, so to avoid it you will have to say that no temporally extended parts of persons have thoughts. But that is even worse, since it take time to have a thought, so now nothing has thoughts. Finally, there seems to be no problem with wholes having properties in virtue of their parts have properties, so your sloppy talk claim doesn’t work very well. Cars have flats and they do so by having flat tyres. So if temporal parts have thoughts, why shouldn’t the whole person have thoughts by having parts that have thoughts?

  4. 4. Posted by Guy Kahane | June 20, 2007 2:22 pm

    I’ve yet to read Stone’s article, so I hope you don’t mind if I make some tangential comments on the remark that open your post.

    First, although if persons had temporal parts these would be obvious candidates for being temporally located selves, I don’t suppose you mean to argue that if the 4D view is false, then the very idea of such selves is incoherent. This surely doesn’t follow since there might be other ways of understanding the relations between selves and persons.

    Second, turning to the normative questions you briefly mention, we should distinguish questions about self-interest and claims about rationality. But I don’t think we need to talk about temporal parts to raise these questions. It’s fairly easy to raise them in terms of a person’s present desires or interests, asking whether he has reasons to fulfil his (predicted) future desires, or to care about his future interests. It’s true that talk about a person’s present interests (as opposed to talk about present desires) is not part of everyday discourse, and may be incoherent, but I don’t think the question of its coherence is decided, or even much illuminated, but this debate in metaphysics.

    There is one way in which there might be a direct connection between these debates. If we allow ourselves to talk about past, present and future selves, we might find it easier to raise the question, ‘why should I, the present self, care now about my future self?’, seeing it as parallel to the question why I should care about the interests of other people. The implicit assumption here is that the normativity of self-interest is self-evident, so if I’m really a present slice of self, there’s no problem explaining why I should care about my present self, but a very genuine problem explaining why I should care about my future self. But this is a highly misleading of raising these questions, and not only because it’s doubtful that ‘I’ refers to any such present self. It’s highly misleading but, as I’ve suggested, not necessary.

  5. 5. Posted by Rebecca Roache | June 21, 2007 4:37 pm

    I’m afraid I haven’t read the Stone article either. But I wonder if it would be useful to consider the analogy with spatial parts. So, the argument might go something like this:
    s1. Suppose, for a contradiction, that 3D is true (i.e. that persons are extended through space and composed of spatial parts).
    s2. Fred has the thought ‘I occupy n cubic centimetres of space’.
    s3. Under 3D, objects extend through space by having spatial parts.
    s4. What it is for a person to have a thought is for a spatial part of the person (such as the brain) to have that thought.
    s5. So Fred has a spatial part, sFredlet, which thinks the thought.
    s6. The thought had by Fred is the same thought as that had by sFredlet.
    s7. Persons (of Fred’s dimensions) occupy n cubic centimetres of space and spatial parts of persons do not.
    s8. So Fred’s thought is true whilst sFredlet’s thought is false.
    s9. So the same thought is both true and false.
    s10. Therefore 3D is false (1, 9, by contradiction).

    It strikes me that the most obvious way to reject this argument is to reject s4 (‘What it is for a person to have a thought is for a spatial part of the person (such as the brain) to have that thought’): we probably want to say something like, it’s true that it is in virtue of having a certain spatial part that a person has a thought, or that the spatial part in question plays a central role in the causal story of how that person came to have that thought; but when we talk about persons having thoughts, we are not using a shorthand for talk of their spatial parts having thoughts. A defender of 4D might say something similar, along the lines of: if we think that ‘Fred has a thought’ is a shorthand way of saying ‘Fredlet has a thought’, we misunderstand the way in which temporal parts of persons relate to persons.

  6. 6. Posted by Nick Shackel | June 23, 2007 1:24 am

    Matthew: I’m not quite sure if I’m understanding how you are proposing that the WC view is avoiding the problem. What is the basis for their interpretation of ‘I am a maximal space time worm’ as ‘Fredlet exists at ~t’ or ‘Fredlet exists at t and Fredlet’s counterparts exist at ~t’?

    Guy: Thanks for these remarks. I don’t think I disagree with them. However, with respect to your remark that “it’s doubtful that ‘I’ refers to any such present self”, Stone argues that under 4D it would (see below in my reply to Rebecca).

  7. 7. Posted by Nick Shackel | June 23, 2007 1:28 am

    Rebecca: This is an interesting analogy. In the spatial case I agree that strategy (D) looks quite strong, especially if we identify the person with the brain. In this case s4 has very little plausibility, since there is not much temptation to think that what it is for a brain to have a thought is for a part of it to have a thought (except among neuroscientists who haven’t understood the personal/sub-personal distinction). However, I think it’s a bit more tricky when it comes to the human animal versus brain. In that case strategy (D) amounts to saying that whilst the brain is the realizer or producer of an ‘I’ thought, it is not the thinker of that thought. Jim Stone discusses this. He is of the opinion that ‘I’ denotes either the whole or part of whatever is available of me to realise the thought. This is not sufficient to determine whether the thinker of the thought is the human animal or the brain. However, in the case of Fred and Fredlet it seems to imply that Fredlet, or some proper part of Fredlet, is the thinker of the thought, thereby undermining strategy (D).

  8. 8. Posted by Paul Torek | August 6, 2007 2:03 am

    I think strategy (C) is the obvious way to go. Indexicals require understanding of something like intent, in order to parse. If my wife says “grab that” and I follow her finger, I can decide that she means the book, or the whole stack of book and papers on the couch. If, mirabile dictu, I’ve actually been paying attention, the broad context of her statement may make it crystal clear that she means the whole stack.

    Human beings, and English speakers in particular, are interested in persons, not their temporal parts. Normally, that is. Fredlet can, with careful conscious effort on Fred’s part, make a statement about Fredlet, but normally he doesn’t.

    My cards on the table, for what it’s worth: I see the 4D “vs” 3D “dispute” as a non-issue. Tomayto, tomahto.

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