Caledonian, the trouble with denying any validity at all to introspective perception is that it would imply that consciousness plays no role in valid cognition. And yet consider the elaborate degree of self-consciousness implied by the construction of the epistemology you just articulated! Are you really going to say you derived all that purely from sense perception and unconscious cognition, with no input from conscious reflection?

Caledonian: "Our perceptions, and most especially our mental self-perceptions, are not veridical. Once we acknowledge that we do not need to [do stuff]"

Do you think "our perceptions, and most especially our mental self-perceptions" are completely valueless? If not, where do you draw the line between valid and invalid?

Allan Crossman: "If a machine can be consistently interpreted as "doing addition", doesn't that indicate that there are intrinsic facts about the machine that have something to do with addition?"

The same physical process, as a computation, can have entirely different semantics depending on interpretation. That already tells you that none of those interpretations is intrinsic to the physical process.

Caledonian: "We don't need a mind to perceive meaning in a pattern of electrical impulses generated by a circuit for that circuit to perform arithmetic. As long as the circuit enforces the correct relationship between input and output values, it implements the mathematical operation defined by that relationship."

See previous comment. There is a physical relationship between inputs and outputs, and then there is a plethora of mathematical (and other) relationships which can be mapped onto the physical relationship.

One may as well say that the words in a natural language intrinsically have certain meanings. If that were true, it would literally be impossible to utilize them in some inverted or nonstandard way, which is false.

Artificial addition is not intrinsically addition, any more than a particular string of shapes on a page intrinsically means anything. There is no "structure that is addition", but there are "structures" that can represent addition.

What is addition, primordially? The root concept is one of combination or juxtaposition of actual entities. The intellectual process consists of reasoning about and identifying the changes in quantity that result from such juxtaposition. And artificial addition is anything that allows one to skip some or all of the actual reasoning, and proceed directly to the result.

Husserl's Logical Investigations has a lot about the phenomenology of arithmetic. That's where I'd go for a phenomenological ontology of addition. Ironically, through the exactness of its analyses the book played a distant role in launching cognitive science and the mechanization of thought, even while its metaphysics of mind was rejected.

The basic distinction is between intrinsic intentionality and derived intentionality. Thoughts have intrinsic intentionality, they are intrinsically about what they are about; words and "computations" have derived intentionality, they are convention-dependent assignments of meaning to certain physical things and processes. Artificial addition only has derived intentionality. If something has "the structure of addition", that means it can consistently be interpreted as implementing addition, not that it inherently does so.

The problem, of course, is that in the physical world it seems like nothing has intrinsic intentionality; everything is just a pile of atoms, nothing inherently refers to anything, nothing is inherently about anything. But there are causal relations, and so we have theories of meaning which try to reduce it to causal relations. B is about A if A has the right sort of effects on B. I think that's backwards, and superficial: if B is about A, that implies, among other things, than A has a certain causal relation to B, but the reverse does not hold. It's one of those things that needs a new ontology to be solved.

This perspective does not alter Eliezer's point. Even if thou art monadic intrinsic intentionality, rather than "physics", you're still something, and decisions still involve causation acting through you.

To respond to the SEED article at slightly greater length... We can start by trying to get a grip on what they mean by "realism". Zeilinger himself says "to give up realism about the moon, that's ridiculous". So the so-called rejection of realism doesn't involve anything like the abandonment of belief in reality (whatever that could mean), just an abandonment of belief in the reality of some things. Calling that a rejection of realism may be rhetorical excess; it is as if I believed there was a cake in the cupboard, discovered there wasn't, and as a result proclaimed that realism about the cake had been falsified.

However, Zeilinger says, "on the quantum level we do have to give up realism". So what does that mean? We believe in things made of particles (like the moon), but not the particles themselves? We believe that big things, like the moon, have properties, but that small ones, like particles, do not? In the end, it seems we are to abandon the belief that small things have properties before we look. No, wait, we are to abandon the belief that small things have the properties we see them to have before we looked. Well, what if they had some other property before we looked, and then the act of looking (measuring, more precisely) perturbed them into a new state with new properties? That would seem to be entirely consistent with what they describe, but what does that have to do with the 'falsification of realism'?

Do I sound exasperated? Pardon me. It is just that there is so, so much nonsense propagated by physicists in the name of physics, and then further passed on by credulous people who are in no position to make an independent judgement about what they've been hearing. The situation is something like this: We have quantum mechanics, which works experimentally. Traditionally, the quantum states (wavefunctions) are not regarded as the fundamental reality of things, they're just a quasi-statistical description which happens to work. So, on the one hand, we have a variety of attempts to explain what the fundamental reality might actually be, and on the other hand, we have - complacency, basically. A frame of mind which is content to use QM as it is, apply it, extend it, but not to dig deeper. Returning to the attempts at a deeper explanation, we have, as SEED mentions, Bohm's theory, which is a nonlocal theory. So long as quantum mechanics continues to work experimentally, Bohm's theory will never be falsified, because it makes exactly the same predictions as quantum theory. On the other hand, Leggett apparently produced a nonlocal theory which does make slightly different predictions. Zeilinger's group did the experiments, quantum mechanics was right, Leggett was wrong - and this is trumpeted as a falsification of realism on the quantum level, for absolutely no good reason that I can see. It is, I suppose, a falsification of the particular postulates that Leggett was trying to uphold, but calling this a falsification of realism is like saying that not finding the cake in the cupboard was a falsification of realism.

Brian M: the basic rule is that if a physicist says something which sounds like mysticism, solipsism, or irrationalism, you ignore it. They are occupational hazards for the philosophizing physicist; you are hearing the effects of a "workplace injury" and nothing more.

Blogs have been turned into books before, e.g. Iraqi bloggers Salam Pax and Riverbend.

In high school I was on a debating team, and I can remember eventually forming the view that it was a potentially corrupting exercise, because you had to argue for the position you were given, not the position that you believed or the position that you might rationally favor. Occasionally the format permitted creative responses; I recall that once, the affirmative team had to argue 'That Australia has failed the Aborigine', and we on the negative team decided to outflank rather than straightforwardly oppose; we said that wasn't true because what Australia had done was much much worse than that. But even that was basically an exercise in lawyerly ingenuity, resulting from a desire to win rather than from a desire to arrive at the truth.

Meanwhile, imagine yet another alternate Earth, where the very first physicists to notice nonlocality, said, "Holy brachiating orangutans, there's a non-local force in Nature!"

In the years since, the theory has been successfully extended to encompass every observed phenomenon. The biggest mystery in physics is the relationship between nonlocality and relativity. The basic equations have a preferred reference frame, but it's undetectable. Everyone thinks that there must be a relativistic way to write the equations, but no-one knows how to do it.

One day, Bavid Dohm walks into the office of Huve Erett...

Bavid gestures to the paper he'd brought to Huve Erett. It is a short paper. The title reads, "The Solution to the Relativity Problem". The body of the paper reads:

"There is no classical trajectory. The pilot wave already contains the world that we see, along with infinitely many others."

"Let me make absolutely sure," Erett says carefully, "that I understand you. You're saying that there is no space-time, as we know it, separate from Hilbert space. There's just the pilot wave, evolving according to the Schrodinger equation. But the pilot wave actually contains space-time - infinitely many space-times."

"Right!" says Bavid.

"Where?" says Erett.

"Everywhere throughout configuration space!" says Bavid. "The configurations are the worlds."

"But if every possible configuration exists, how do you predict anything?" asks Erett.

"Er, well, it's not the configurations which are the worlds, then", says Bavid. "It's the blobs of amplitude hovering over the configurations."

"I still don't see how you make predictions. Or eliminate a universal time coordinate", says Erett.

"Decoherence!" says Bavid. "If you don't count the blobs where the amplitude really thins out, then the numbers come out correctly."

"But the blobs are still there?" asks Erett.

"Yes... they're just... thinner", says Bavid.

"Why shouldn't I count them, then?" asks Erett.

"Because the numbers won't come out right otherwise!" says Bavid.

"I see", says Erett. "And relativity? You did say this is a relativistic theory."

"Yes, well, my idea is to get rid of time entirely", says Bavid.

"Ah yes, the old 'H=0' approach. The pilot wave is a standing wave. But how is that relativistic? Relativity mingles space and time. H=0 just abolishes time and leaves space", says Erett.

"Er..." says Bavid.

At which point Erett politely but firmly shows Mr Dohm out of his office.

But the probability that anyone is immortal in any specific branch is basically zero. There is a nonzero probability of death per unit time, and so the probability of literal immortality is infinitesimal, being a product of infinitely many quantities less than 1.