[Max Goodman]

Hoffman’s book (which I haven't finished reading) argues convincingly that our perceptions might not show reality—an intriguing idea. But his assumption that objective reality is vastly unlikely be the “reality” we perceive still seems an assumption. In fact, in places, I think I catch outright errors in his thinking. I share two here to give you smart folks a chance to show me that I’m wrong, as you’ve recently helped me solve other more mundane problems.

In chapter 4, to dispute the claim that (I understand to be that) his theory can’t be accurate because it does not propose a reality to replace the one we think we perceive, he writes “Suppose that I tell you that p is some particular claim and q is some particular claim, but I refuse to tell you what either claim is. Then … suppose that I … claim ‘if either p is true or q is true then it follows that p is true.’ … You know that this claim is false, even though you don’t know the contents of p or q."

That’s plain wrong (right?)—in way that doesn’t invalidate his theory, but does fail to falsify the counterargument. It’s easy to choose a p and q for which it is true that “if either p is true or q is true then it follows that p is true.” For instance:

p = All Australians are at least 10 feet tall.
q = All Australians are at least 11 feet tall.

It is also possible (probable, it seems to me) that objective reality and the fitness payoffs natural selection has fashioned our senses to perceive are at least as closely related as these two claims.

**

Hoffman admits that fitness payoffs change depending on an organism’s needs. A hungry teen, he says, perceives great fitness payoffs in a pizza. But six slices later, the same teen reacts differently to the same pizza. The fitness payoffs are no longer there. Doesn’t this falsify Hoffman’s belief that perceiving fitness payoffs makes it unlikely that we accurately perceive reality? If our perception of fitness payoffs showed something unreal, wouldn’t that unreal thing change as the fitness payoffs it was designed to direct us toward changed?

(Of course, the pizza has changed in the sense of being six slices lighter, but the fitness payoffs of a given pizza are different to a teen who hasn't eaten in several hours than to one who has just consumed a different pizza, without, I think, changing the pizza as perceived by the teen.)

Added: Maybe the pizza issue is resolved by regarding what I've dismissed as the teen's changing reaction as part of the teen's perception? The pizza's smell, look, feel, and taste are the same whether or not the teen's eaten, but the whole package is perceived as a "delicious pizza" when it points the teen toward a(n unknown, according to Hoffman) fitness payoff, and as a "disgusting pizza" when it warns the teen away from the fitness penalty that we (from the standpoint of our limited perspective) describe as overeating.