The folk history of psychology has it that the early efforts of folk such as Wundt and Titchener failed because they relied on introspection. Simply looking into your own mind and reporting what you thought you saw there was hopelessly unscientific, and once a disagreement arose about what thoughts were like, there was nothing the two sides could do but shout at each other. That is why the behaviourists, in an excessive but understandable reaction, gave up talking about the contents of the mind altogether, and even denied that they existed.

That is of course a terrible caricature in a number of respects; one of them is the idea that the early psychologists rushed in without considering the potential problems with introspection. In fact there were substantial debates, and it’s quite wrong to think that introspection went unquestioned. Most trenchantly, Comte declared that introspection was useless if not impossible.

As for observing in the same manner intellectual phenomena while they are taking place, this is clearly impossible. The thinking subject cannot divide himself into two parts, one of which would reason, while the other would observe its reasoning. In this instance, the observing and the observed organ being identical, how could observation take place? The very principle upon which this so-called psychological method is based, therefore, is invalid.

I don’t know that this is quite as obvious as Comte evidently thought. To borrow Roger Penrose’s analogy, there’s no great impossibility about a camera filming itself (given a mirror), so why would there be a problem in thinking about your thoughts? I think there are really two issues. One is that if we think about ourselves thinking, the actual content of the thought recedes down an infinite regress (thinking about thinking about thinking about thinking…) like the glassy corridor revealed when we put two mirrors face to face. The problem Comte had in mind arises when we try to think about some other mental event. As soon as we begin thinking about it, the other mental event is replaced by that thinking. If we carefully clear our minds of intrusive thoughts, we obviously stop thinking about the mental event. So it’s impossible: it’s like trying to step on your own shadow. To perceive your own mental events, you would need to split in two.

John Stuart Mill thought Comte was being incredibly stupid about this.

There is little need for an elaborate refutation of a fallacy respecting which the only wonder is that it should impose on any one. Two answers may be given to it. In the first place, M. Comte might be referred to experience, and to the writings of his countryman M. Cardaillac and our own Sir William Hamilton, for proof that the mind can not only be conscious of, but attend to, more than one, and even a considerable number, of impressions at once. It is true that attention is weakened by being divided; and this forms a special difficulty in psychological observation, as psychologists (Sir William Hamilton in particular) have fully recognised; but a difficulty is not an impossibility. Secondly, it might have occurred to M. Comte that a fact may be studied through the medium of memory, not at the very moment of our perceiving it, but the moment after: and this is really the mode in which our best knowledge of our intellectual acts is generally acquired. We reflect on what we have been doing, when the act is past, but when its impression in the memory is still fresh. Unless in one of these ways, we could not have acquired the knowledge, which nobody denies us to have, of what passes in our minds. M. Comte would scarcely have affirmed that we are not aware of our own intellectual operations. We know of our observings and our reasonings, either at the very time, or by memory the moment after; in either case, by direct knowledge, and not (like things done by us in a state of somnambulism) merely by their results. This simple fact destroys the whole of M. Comte’s argument. Whatever we are directly aware of, we can directly observe.

And as if Comte hadn’t made enough of a fool of himself, what does he offer as as an alternative means of investigating the mind?

 We are almost ashamed to say, that it is Phrenology!

Phrenology! ROFLMAO! Mill facepalms theatrically. Oh, Comte! Phrenology! And we thought you were clever!

The two options mentioned by Mill were in essence the ones psychologists adopted in response to Comte, though most of them took his objection a good deal more seriously than Mill had done. William James, like others, thought that memory was the answer; introspection must be retrospection. After all, our reports of mental phenomena necessarily come from memory, even if it is only the memory of an instant ago, because we cannot experience and report simultaneously.  Wundt was particularly opposed to there being any significant interval between event and report, so he essentially took the other option; that we could do more than one mental thing at once. However, Wundt made a distinction; where we were thinking about thinking, or trying to perceive higher intellectual functions, he accepted that Comte’s objection had some weight. The introspective method might not work for those. But where we were concerned with simple sensation for example, there was really no problem. If it was the seeing of a rose we were investigating, the fact that the seeing was accompanied by thought about the seeing made no difference to its nature.

Brentano, while chuckling appreciatively at Mill’s remarks, thought he had not been completely fair to Comte. Like Wundt, Brentano drew a distinction between viable and non-viable introspection; in his case it was between perceiving and observing. If we directed our attention fully towards the phenomena under investigation, it would indeed mess things up: but we could perceive the events sufficiently well without focusing on them. Wundt disagreed; in his view full attention was both necessary and possible. How could science get on if we were never allowed to look straight at things?

It’s a pity these vigorous debates are not more remembered in contemporary philosophy of mind (though Eric Schwitzgebel has done a sterling job of bringing the issues back into the light). Might it not be that the evasiveness Comte identified, the way phenomenal experience slips from our grasp like our retreating shadow, is one of the reasons qualia seem so ineffable? Comte was at least right that some separation between observer and observed must occur, whether in fact it occurs over time or between mental faculties. This too seems to tell us something relevant: in order for a mental experience to be reported it must not be immediate. This seems to drive a wedge into the immediacy which is claimed to generate infallibility for certain perceptions, such as that of our own pains.

At any rate we must acquit Wundt, Titchener and the others of taking up introspection uncritically