In previous installments of my series on Freud as a philosopher I described how during Freud’s lifetime the sciences of the mind were guided by assumptions about the nature of the mind and its relation to the body that he came to reject. These included the notion that mind and body are categorically distinct (“dualism”), that all mental processes are conscious, and that the best way to explore the mind is through introspection.  

Freud turned his back all these propositions. Instead, he arrived at the view that mental states are brain states (“materialism”), that mental processes are unconscious, that we have only indirect access to our own minds, and that introspection is an inadequate tool for exploring the mind. This philosophical shift was crucial for his creation of the theory and practice of psychoanalysis. In this essay I want to explain a bit about how Freud arrived at this position by laying out one of his key arguments. He didn’t give the argument a name, so I’ve taken the liberty of calling it the continuity argument.  

The continuity argument was inspired by several sources. One was John Stuart Mill’s book Examination of the Philosophy of Sir William Hamilton which Freud purchased in 1889. In the book, Mill cites a remark by Hamilton that:

It sometimes happens that we find one thought rising immediately after another in consciousness, but whose consecution we can reduce to no law of association. Now in these cases we can generally discover… that these two thoughts… are each associated with certain other thoughts, so that the whole consecution would have regular, had these intermediate thoughts come into consciousness….

Other sources included the physiologist Ewald Hering, the philosopher Theodor Lipps, who influenced him greatly, and possibly even David Hume. But Freud didn’t simply appropriate the thoughts of others. He used them to develop a powerful and original argument that goes well beyond what his predecessors had said.

The continuity argument takes off from the observation that our conscious mental life is both gappy and continuous across the gaps. Here’s how Freud expressed this idea in his 1915 paper “The Unconscious” (one of the most philosophical of his works).

The data of consciousness have a very large number of gaps in them; both in healthy and in sick people psychical acts often occur which can be explained only by presupposing other [psychical] acts, of which, nevertheless, consciousness affords no evidence…. [O]ur most personal daily experience acquaints us with ideas that come into our head, we do not know from where, and with intellectual conclusions arrived at we do not know how.

Freud was right that this is very easy to confirm from personal experience. Here’s an example. A little while ago, I took a break from working on this essay and took a nap. I lay down on the living room sofa and quickly fell into a deep, dreamless sleep. I woke up after twenty minutes or so with some fresh ideas in my head about how to develop this essay. So, there was a gap in my conscious mental life (the nap) and there was continuity across the gap (I woke up with some fresh ideas about how to proceed with the essay).

But hold on, there seems to be a contradiction here! How can mental sequences be simultaneously continuous and gappy? Freud shows us how to resolve this seeming contradiction by letting go of some incorrect assumptions about the nature of the human mind.

Here’s how the argument goes. Suppose, as many of Freud’s contemporaries did, that all mental processes are conscious. It follows that if there are gaps in our conscious mental lives, then nothing mental was going on during those gaps. So, on this view, when I was napping, there wasn’t anything at all going on in my mind. But if the thoughts that occur after a gap are continuous with thoughts that occurred before the gap—in other words, if our conscious thoughts are continuous across the gaps—then there’s got to be something going on that secures this continuity. A knee-jerk response might be “Well, there’s unconscious brain activity going on, so couldn’t we just say that what’s happening during a gap isn’t really mental at all—that it’s just mindless physical neuron-firings?”

Well we could say that, but it wouldn’t really help, because whatever’s taking place during these gaps in consciousness has got to be able to preserve mental continuity. It’s got to be able to explain how it was possible for me to make progress on an essay while I’m asleep. To accomplish that, it looks like whatever was going on in my brain while I was napping couldn’t have been mindless. If we grant—as Freud thought we should—that my brain was churning away unconsciously during the nap, we should also conclude that these neurophysiological churnings were mental in nature.

Freud’s continuity argument leaves us with three very striking conclusions that contradict the pre-Freudian assumptions that I spelled out in the first paragraph of this essay. One is that mental processes can be entirely unconscious, and another is that mental processes are the very same thing as brain processes. And this implies that, as Freud put it in 1895, introspection gives us “neither complete nor trustworthy knowledge of the neuronal processes” which are “to be regarded to their whole extent as unconscious and are to be inferred like other natural things.”  

My original plan was to end my Freud series here. But then I thought to myself “David, how can you write a series about Freud without discussing his views about sex?” So, next month I’ll wrap up the series with an essay on Freud’s philosophy of sex.