Here's my take on it.
Agnosticism is illogical and refutes itself. Agnosticism and agnostics characterize God as unknowable, ineffable, incomprehensible to all attempts to understand him. This doctrine is self-refuting. The agnostic is making a knowledge claim about what he/she claims is unknowable. How do agnostics know that God is unknowable if he is unknowable ? How do they even know that God's existence cannot be disproved if God is unknowable, or that God even exists if he is unknowable ? To claim any attribute for God is knowledge and claims to know this unknowable God possesses certain attributes. That's a logical contradiction, and any being containing two incompatible attributes cannot possibly exist. So one need not resort to agnosticism. He/she would be justified in not believing in that God if the concept of it contradicts itself in any way. One is justified in accepting and adopting the atheist position.
I mean, the gist of Penrose's argument in The Emperor's New Mind was that if human thought does not involve a quantum element, if it is classically deterministic, he could derive a contradiction, in a handwaving way, via Goedel's incompleteness theorem.
Give me the exact reference. Throughout his book Penrose mentions Gödel's incompleteness theorem many times. His discussions are informal and speculative and this is an area where precision is necessary.
The part where he's most explicit about his argument (as I remember) is where he has the human inventor of a robot arguing with the robot, and in time the robot breaks down because of the argument :) Starts fizzing or something :)
Can you be more explicit—give a page reference or at least a chapter. The book is long and sprawls over a lot of territory and Penrose tosses out an enormous number of ideas.
Apparently this dialog is actually in Penrose's Shadows of the Mind, pgs 179-190. A book I don't have either.
I have read several of his books, but not that one and I don't own a copy.
The dialog between the robot and its creator is in section 3.23 of Shadows of the Mind. It's a challenging and thought-provoking summary of Penrose's arguments from Goedel's theorem.
Shadows of the Mind was a followup of The Emperor's New Mind where Penrose tried to make his arguments more rigorous and technical. There's even a pdf online with Penrose's answer to the criticisms of his argument in Shadows of the Mind.
The programs, experience, memory, etc. can be incorporated into the basic Turing-machine model. Those things in themselves don't make us fundamentally different from a Turing machine.
but the question still remains, if a person is a Turing machine, what gets in the way of them proving their own Goedel sentence? A Turing machine has an equivalent to its Goedel sentence, as I vaguely remember (?)
Here's a paper online that summarizes the Lucas-Penrose argument that people aren't Turing machines.
One can turn it into an argument that some things are unknowable: if we are Turing machines there are truths we will never know.
but in your hard drive analogy...isn't it just a matter of learning how to do the readout? And surely there will be general principles (i.e. the software) of, for example, how memories are formed and stored, how executive function(s) operate etc
The point is that individual brains may be organized in quite different ways—that is, programmed in different languages—and without a key given in advance the task of decrypting stored messages is extraordinarily difficult and as a practical matter, impossible. It's like the problem of translating an unknown language. After all these years linear A remains undeciphered. The problem with individual brains may be much harder.
I don't believe in agnosticism as a separate classification. To me it's a qualifier of belief. That is, when I say I'm an 'agnostic atheist', I mean that I lack a personal belief in a god but I recognise that we probably won't ever know for sure (because we can't prove a negative that way). People that use the term agnostic as a stand-alone identification I tend to be suspicious of, because their opinion on whether or not the existence of a god can be factually known doesn't speak at all to their personal belief or lack thereof.
I do also classify myself as an “agnostic atheist”, but I think agnostic is a qualifier of knowledge. I am an agnostic because my lack of knowledge about god’s existence/inexistence. I am an atheist because my lack of believe in god’s existence. And I do not consider myself a “weak” atheist. I am a strong atheist, almost an antitheist.