In "The Unimagined Preposterousness of Zombies", Daniel Dennett says:

To date, several philosophers have told me that they plan to accept my challenge to offer a non-question-begging defense of zombies, but the only one I have seen so far involves postulating a "logically possible" but fantastic being — a descendent of Ned Block's Giant Lookup Table fantasy...

A Giant Lookup Table, in programmer's parlance, is when you implement a function as a giant table of inputs and outputs, usually to save on runtime computation. If my program needs to know the multiplicative product of two inputs between 1 and 100, I can write a multiplication algorithm that computes each time the function is called, or I can precompute a Giant Lookup Table with 10,000 entries and two indices. There are times when you do want to do this, though not for multiplication—times when you're going to reuse the function a lot and it doesn't have many possible inputs; or when clock cycles are cheap while you're initializing, but very expensive while executing.

Giant Lookup Tables get very large, very fast. A GLUT of all possible twenty-ply conversations with ten words per remark, using only 850-word Basic English, would require 7.6 * 10⁵⁸⁵ entries.

Replacing a human brain with a Giant Lookup Table of all possible sense inputs and motor outputs (relative to some fine-grained digitization scheme) would require an unreasonably large amount of memory storage. But "in principle", as philosophers are fond of saying, it could be done.

The GLUT is not a zombie in the classic sense, because it is microphysically dissimilar to a human. (In fact, a GLUT can't really run on the same physics as a human; it's too large to fit in our universe. For philosophical purposes, we shall ignore this and suppose a supply of unlimited memory storage.)

But is the GLUT a zombie at all? That is, does it behave exactly like a human without being conscious?

The GLUT-ed body's tongue talks about consciousness. Its fingers write philosophy papers. In every way, so long as you don't peer inside the skull, the GLUT seems just like a human... which certainly seems like a valid example of a zombie: it behaves just like a human, but there's no one home.

Unless the GLUT is conscious, in which case it wouldn't be a valid example.

I can't recall ever seeing anyone claim tha...

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