I've recently read Galen Strawson's 2011 book, THE EVIDENT CONNEXION: HUME ON PERSONAL IDENTITY. It is a follow-up of sorts to his book on Hume's theory of causation, which I discussed in a series of posts last January.
Hume believed himself to have been defeated in his efforts to explain personal identity. He says so pretty clearly in an APPENDIX he added in 1740 to his TREATISE ON HUMAN NATURE, though one of Strawson's point is that many other scholars don't seem to have realized how complete the confession of failure here is.
Here is Hume.
I had entertain’d some hopes, that however deficient our theory of the intellectual world might be, it wou’d be free from those contradictions, and absurdities, which seem to attend every explication, that human reason can give of the material world. But upon a more strict review of the section concerning personal identity, I find myself involv’d in such a labyrinth, that, I must confess, I neither know how to correct my former opinions, nor how to render them consistent.
[After several paragraphs restating his theory, he gets back to why it seems to have self destructed]:
But having thus loosen'd all our particular perceptions, when I proceed to explain the principle of connexion, which binds them together, and makes us attribute to them a real simplicity and identity; I am sensible, that my account is very defective, and that nothing but the seeming evidence of the precedent reasonings cou'd have induc'd me to receive it. If perceptions are distinct existences, they form a whole only by being connected together. But no connexions among distinct existences are ever discoverable by human understanding. We only feel a connexion or determination of the thought, to pass from one object to another. It follows, therefore, that the thought alone finds personal identity, when reflecting on the train of past perceptions, that compose a mind, the ideas of them are felt to be connected together, and naturally introduce each other. However extraordinary this conclusion may seem, it need not surprize us. Most philosophers seem inclin'd to think, that personal identity arises from consciousness; and consciousness is nothing but a reflected thought or perception. The present philosophy, therefore, has so far a promising aspect. But all my hopes vanish, when I come to explain the principles, that unite our successive perceptions in our thought or consciousness. I cannot discover any theory, which gives me satisfaction on this head.
In short there are two principles, which I cannot render consistent; nor is it in my power to renounce either of them, viz, that all our distinct perceptions are distinct existences, and that the mind never perceives any real connexion among distinct existences. Did our perceptions either inhere in something simple and individual, or did the mind perceive some real connexion among them, there wou'd be no difficulty in the case. For my part, I must plead the privilege of a sceptic, and confess, that this difficulty is too hard for my understanding. I pretend not, however, to pronounce it absolutely insuperable. Others, perhaps, or myself, upon more mature reflections, may discover some hypothesis, that will reconcile those contradictions.
Strawson's book is an extended meditation on this passage. The gist of Strawson's view appears at pp. 150-51.
Some background before we quote that. Strawson sees Hume's philosophy as a series of three reductions, though he emphasizes that each reduction is epistemological, not metaphysical. Thus, consider first physical objects like tables, trees, backgammon sets. All we can know about them in a philosophically respectable way is that each is a certain clump of qualities that appears to obey laws. It may be the case metaphysically that there is more to the tree than the sight of treeness, the smell of tree-odor, the rough feel of bark, etc., it is rational to entertain theories of that something else [Locke's or Berkeley's theory or other unspecified theories], but it is philosophically vain to do so, since we can never know more than what we perceive.
Second, consider cause and effect. On a pool table the cue ball approaches the 4 ball, hits it, stops and at the same moment that one motion stops the other begins -- the 4 ball moves forward in the same direction. We tend to postulate a real connection, which we call "causation," between the movement of the cue ball and the movement of the 4 ball. Hume doesn't argue with this metaphysically -- again, on Strawson's view at any rate, he thinks there likely is some sort of connection, but it is and must remain hidden from us. Hume argues with our commonsensical notions on an epistemological level, saying that all we can know is the regularity of such events, and hypotheses beyond that are vain.
Third, there is the specific subject of this book, the notion of the self or (Strawson takes it that Hume took this to be the same thing), the notion of the mind. Again, S takes it that H was a Kantian before Kant, that he wants an epistemological reduction, while leaving metaphysics out of account. The "noumenal" as it would be called, is whatever it is -- it is vain for us to speculate. What we know about ourselves consists of ideas that are, as the above passage says, a train of perceptions that are felt to be connected together. The feeling may stand on a reality, but we can't know that, or what it is.
So ... here is the problem. The reduction that works well enough on its own terms in regard to external objects and causal relations between them can't apply to the mind, because the mind is that which keeps making the mistakes, positing the fictions, which this philosophy seeks to reduce. The human mind is that which keeps postulating a more to the tables and trees, which keeps postulating that the one pool ball imparts its motion to the other. Fictions (in some sense) though these may be, they are the actions of an active mind, and they happen in accord with some principles. Hume can't consistently exclude that action and those principles from philosophic knowability, since his whole philosophy is built on knowing them. That is how, on Strawson's view, Hume had worked himself into a difficulty hat he describes as "too hard for my understanding."
Hume's principles about how the mind supposedly works are what Strawson calls the I-principles, where the letter "I" refers to Hume's extended use of the word "imagination." The I-principles include, for example, contiguity. Thought of the idea of a room leads to thought of the room next door to it. The point for the moment is that I-principles are operations of an enduring active self/mind.
Thus the Strawson quote I promised is finally ready for us:
One can put the point by saying that the existence and operation of the I-principles means that some metaphysical description of the mind that Hume can't avail himself of is knowably applicable to the mind. He can't invoke the mind's 'unknown essence,' treating this as a kind of explanation-sink that can absorb the whole difficulty, for ... his opponents can happily grant that of course much must remain unknown, while continuing to insist that Hume has in appealing to the I-principles invoked something-- some sort of genuine metaphysical connection and continuity among the experiences of the mind -- whose existence he can make sense of only on one of two conditions, neither of which is available to him. Once again, one can say that the trouble with his empiricist account of the mind is not so much that it doesn't include anything that might satisfy either of those conditions as that it definitively excludes any such thing.
Strawson's reference there to the "two conditions" is to the above Hume passage, where Hume writes, Did our perceptions either inhere in something simple and individual, or did the mind perceive some real connexion among them, there wou'd be no difficulty in the case.
But Humean philosophy excludes either condition, as a hypothesis, from philosophical respectability. The first sounds like the invocation of a knowable soul, something Hume rejects. The second postulates a succession of mind states in which each would be the cause of the next one and the effect of the one before, in a strong metaphysical sense of "causation" which again is something Hume rejects. This, on Strawson's reading means that Hume's confession here, that "all my hopes vanish," means that this philosophizing has reached a dead end, where many other Hume scholars have seen only a quandary on a matter of detail.
This analysis also includes a compare-and-contrast exercise involving Hume and William James, one that belongs in any blog entitled "Jamesian Philosophy Refreshed." I'll speak some more of the Jamesian aspect of Strawson's book soon, in a separate posting.