Perception: A Representative Theory by Frank Jackson

Frank Jackson is a well-known philosopher from Australia. Perception, first published in 1977, is┬áan argument for a Representative theory of visual perception similar to John Locke’s. Jackson┬ásums up the book in the last paragraph:

The first four chapters present my case for a Sense-datum theory of perception. Chapter 5 gives the reason for holding that all sense-data are mental. This forces a choice between Idealism and Representationalism. In chapter 6, I argue that there is no good reason for not choosing Representationalism. And, finally, in [the last] chapter, I have, first, attempted to justify my taking the perception of things as basic throughout; and, secondly, I have tried to make more precise … the particular kind of Representationalism that should be chosen.

The Sense-Data theory of perception┬áhas had a long history in philosophy. Its principal tenet is that we never┬áperceive physical objects directly. Instead, what we immediately perceive are mental objects called “sense-data”. Thus,┬áwhen I see the wall in front of me, I immediately perceive a mind-dependent blue expanse, a sense-datum (or set of sense-data), not the wall itself. In Jackson’s words, a visual sense-datum is “something seen, but not in virtue of [seeing] anything else”. Physical objects, on the other hand, are seen, but always by virtue of seeing something else, namely, sense-data. Furthermore, there is a kind of causal relationship between physical objects and the sense-data that “belong to” those objects. That’s why sense-data are said to “represent” the external world.

I’ve read that Jackson no longer endorses the theory he presents here, but Perception┬ástill provides a good account of one version of the Sense-Data theory. Professor Jackson┬ámakes many interesting distinctions and responds to a number┬áof criticisms. One criticism he anticipates is that he is spending┬átoo much time analyzing the language of perception (Chapter 2, for example, is called “Three Uses of ‘Looks'”). He responds┬áthat his analysis of language isn’t meant to show whether sense-data actually exist. Instead, it’s meant to help us decide┬áwhether believing┬áin the existence of sense-data (accepting the theory) is a reasonable thing to do and how the theory should be stated.

I read Perception because I’ve been thinking about the topic a lot lately and think the Sense-Data theory is probably the best one (even though it’s probably considered a bit old-fashioned now; for one thing, philosophers talk about “qualia” these days instead of sense-data). It’s common for philosophers to think of the mind as software running┬áon the hardware of the brain. But if we’re going to think of our minds/brains as computers running programs, it makes sense to think of the input to these computers as data. Just as a computer program processes data and not the real stuff in the world, we process data as well. In our case, colors, sounds, smells, and so on, are different kinds of data. It just so happens that the data we process isn’t made up of numbers or ASCII characters (or electronic on/off settings);┬áour perceptual data is made up of red or blue expanses, soft or loud noises and pleasant or unpleasant aromas. We don’t perceive the world “directly”, because that can’t be done. We perceive sense-data that represent the world; in similar fashion,┬ácomputers process electronic values┬áthat┬árepresent the world too.

Pain, Rigor and Clarity (or How a Pain in the Foot Can Be a Pain in the Neck)

Frank Jackson is a distinguished philosopher who teaches in Australia. He does “analytic” philosophy, the kind most academic philosophers in the U.S. and U.K. do.┬áAnalytic philosophers tend to take science seriously, try to offer logical arguments for their positions and often analyze the meanings of common linguistic expressions. They also generally aim for both clarity and rigor in their written work.

Being interested in the philosophy of perception, I’ve been reading Perception: A Representative Theory, one of Professor Jackson’s books. It deals with traditional philosophical questions like this: “Since┬áscience tells us that┬áphysical objects like apples and oranges┬áaren’t really colored – they only look colored when we perceive them┬á– and┬áthere aren’t any colors inside our brain cells – neurons don’t have tiny┬áred and orange pictures inside them – where exactly are the colors we see?”

In a chapter called “The Existence of Mental Objects”, Jackson spends several pages discussing bodily pain, in particular, whether pains have locations in the same way that things like fruit and furniture do. For various reasons, some philosophers have denied┬áthat pains have spatial locations. So a┬ápain in my foot, for example, isn’t literally “in my foot”.

All of which I’ve┬ámentioned so far, simply as a preliminary to sharing the following sentence from┬áJackson’s book (page 84):

It is certainly not the case that “I had a pain in my foot” entails that if I had not known that the cause of my pain was not in my foot, then I would have believed that the cause was in my foot; for one way of not knowing that the cause is not in my foot is having no opinion on whether the cause is or is not in my foot, so it might well have been the case that if I had not known the cause was not in my foot, I would neither have believed that it was or that it was not in my foot.

Having read this sentence quite a few times, it is my contention that, in this case, Professor Jackson chose rigor over clarity.