Clark is a wonderful writer with compelling, unexpected ideas. My only complaint with this book is that it is repetitive. Clark’s key ideas could be spelled out in probably one chapter’s length, and the rest of the book involves applications of these ideas across various contexts, like explaining everyday illusions and psychopathological symptoms. He also spends a good amount of time on his more speculative “extended mind” thesis as a statement about the metaphysics of mind, which I’m not as interested in, and don’t find as convincing. This repetitive quality, however, is natural, given its genre as a book-length project pitched at a general audience.
For readers who want to get directly to the heart of Clark’s ideas, I’d recommend two papers of his, which represent different philosophical projects of his. First, there’s “Dreaming the Whole Cat: Generative Models, Predictive Processing, and the Enactivist Conception of Perceptual Experience” (2012), which presents his ideas on predictive processing. The ideas in this paper are repeated in this book. The basic idea is that a compelling picture of mental processing is that there are many hierarchical models, like layers, where the higher ones try to predict the patterns in the lower ones. We are driven to act in ways which alter sensory input so that these predictions can be done more quickly and successfully.
For example, when we see a tomato, we see the whole tomato, even though the visual data coming in reflects just one side of it. This seeing the whole is made possible by the fact that higher levels of our mental model of the world are trained to yield that the best prediction of what is going on in the world, in light of this sensory input, is that there’s a whole tomato. So we see the whole. In other words, we perceive and experience what our brains predict is most likely, rather than what’s literally coming in.
Moreover, unbeknownst to us, our actions and expectations are always for the sake of minimizing error. If a prediction is erroneous, the brain will come up with what it takes to be the most likely hypothesis to explain why the error happened, and our experience will altered accordingly, if this hypothesis were correct. For example, if I bite into the tomato, and it tastes too sugary to be a tomato, I quickly experience it as some sweet fruit I’ve mistaken, and later a friend confirms that it was a persimmon. If usually whenever I see my friend we are high energy and greet each other enthusiastically, and this time around he is low energy, I quickly experience him as sad or tired. If I were in a socially anxious mood, I might experience him as having a grudge against me, or some other explanation of the prediction error that seems most likely, in light of this mood.
The second paper I’d recommend, which gets to the heart of Clark’s ideas repeated much throughout this book, is “Word, niche and super-niche: how language makes minds matter more” (2005). Here, Clark explores a speculative but I find compelling idea: our language use has added a “dimension” to reality, which systematically changes the possibilities of perception and thought. Particularly, language, being abstract, offers labels/categories, which particulars get tagged with, so that we can deal with large swathes of particulars at a single blow, a single perception or thought. Reality becomes “symbolic,” where single things come to be registered as many possible things, and dealing with the former is a proxy for dealing with the latter. This tagging also allows for enhanced powers of selective attention. When much is going on, we can focus on a few things, those we’ve chosen by implicitly using language about it. This ties in with our enhanced agency; we can control our environments and lives by selective attention. We need not literally use language to achieve these effects; explicitly using language “scaffolds” our cognitive and perceptual skills, so that without explicitly using it, we can have perceptions and thoughts akin to those that’d occur if we did.
I have a side-thought about a possible tension between these two philosophical projects of Clark’s. His predictive processing model of cognition suggests that all mental activities (those traditionally called perception vs imagination vs reasoning, for example) can be sufficiently understood by one and the same vocabulary of “perceptual experience” and one and the same model of cognition. But it seems that there are crucial differences between these types of mental activity. Clark appreciates this in his work on the role of language use in the development of human cognition; using language isn’t the same as passively perceiving the world, and it changes the possibilities of later passive experiences.
I’d like to see work done on trying to fit such points about agency and selective attention, as distinctive powers of language use, under the predictive processing framework. I’d fancy these most neatly fit under the concept built into the framework regarding the hierarchical levels of prediction; the higher order levels correspond to our personal agency and experience, and our deliberately challenging or making sense of our experiences via language use could be understood as predictive activities going on at these higher levels.
The issue with this, however, is that there is reason to doubt that “prediction” can amount to the same sort of mental activity between the deliberate, language-based sort, on the one hand, and the automated, information-processing sort, on the other hand. When I consciously or deliberately wonder why my friend seems blue, this is self-conscious, and so anything I think of will “spark off” in my consciousness objections or alternatives, or additional associations which vindicate or supplement what I’m coming up with. I can always challenge whatever is sparked off in my mind. In contrast, the prediction that goes down at the lower levels of cognition does not involve this possibility of sensitive monitoring, of challenging or elaborating upon itself (unless we want to posit a homunculus picture of the mind, where there is a little person who makes up our brain and has its own autonomy and mental will, independent from our own; and this kicks off an undesirable regress).
Maybe there’s something to that such predictions that use language are going on at lower levels, and there’s no need to posit a homunculus; the difference between the mental activity of “prediction” at those levels, and that of the higher level of our own volition, is a matter of our turning our attention to the happenings at those levels, like a spotlight illuminating that which was previously dark. But this picture leaves unexplained what this volitional attention consists in; if we rely upon Clark’s predictive processing model, it would need to be explained in terms of happenings at the lower levels once more. There seems to be no entry point in his model for our personal agency to come in, to be appreciated as significantly distinct from whatever automated information-processing that goes on in the brain.
Clark appreciates our agency, which comes out in his work on language use. The fact that his predictive processing work doesn’t neatly accommodate his ideas about agency amounts to a tension which whose resolution I’d like to see.
One more complaint about collapsing distinct types of mental activity under the language of perception and under one processing model: I worry that information we consciously retrieve or create, at those higher levels, has different “affordances.” The affordances might be distinct on the basis of whether such information we consciously manipulate is episodically remembered, or creatively imagined, or created in a self-disciplined manner according to certain norms, either ethical or epistemological—not even yet to speak of the difference between these affordances, as a whole, and the affordances of information that is subpersonally manipulated.
For example, consider the differences in “affordances” of information we consciously deal with. If I’m remembering a past experience with my friend, I sense this as tied to reality, and it will shape my reasoning as if it were true. In contrast, if I fancifully imagining my friend (as smoking too much again as a possible explanation to his blue mood, when I have no evidence at all that he has done this), this imagining will not shape my reasoning in this way. In contrast, whatever information low levels of cognitive processing deal with have neither affordance; in order for them to have either, we must conscious attend to it (or “let it rise” to conscious awareness through some other means), and by that point, it is no longer the same kind of information (e.g., sensory data v an understood, intelligible state of affairs).
Anyways, Clark’s ideas are compelling and fun to engage with (as reflected in my rambling above perhaps). Read this book if you want to see these ideas introduced in a non-technical way and worked out under the context of a range of everyday experiences.