This seems like a fully general counter-argument against any self-representation: there is always a level you have to stop at, otherwise even modeling quarks and leptons is not good enough. As long as this level is well understood and well described, what’s the benefit of digging further?
Sure, but the point is that there are plenty of questions about oneself that aren’t necessarily answerable with only the source code. If I want to know “why am I in a bad mood this morning”, I can’t answer that simply by examining my genome. Though that’s admittedly a bad example, since the genome isn’t really like a computer program’s source code, so let me try another: if you want to know why a specific neural net failed in some specific discrimination task, it’s probably not enough to look at the code that defines how abstract neurons should behave and what the learning rules are like, you also need to examine the actual network—held in memory—that those rules produced.
Of course you might be capable of taking a snapshot of your internal state and then examining that, but that’s something quite different from doing a quine. And it means you’re not actually examining your current self, but rather a past version of it—something that probably wouldn’t matter for most purposes, but it might mattter for some.
but the point is that there are plenty of questions about oneself that aren’t necessarily answerable with only the source code.
This may well be a valid point in general, depending on the algorithm, but I am not sure that applies to a quine, which can only ask (and answer) one question. And it is certainly different from your original objection about machine registers and such.
This may well be a valid point in general, depending on the algorithm, but I am not sure that applies to a quine, which can only ask (and answer) one question.
What do you mean? Assuming that a quine can only answer a question about the source code (admittedly, the other commenters have pointed out that this assumption doesn’t necessarily hold), how does that make the point of “the source code alone isn’t enough to represent the whole system” inapplicable to quines?
And it is certainly different from your original objection about machine registers and such.
I don’t follow. Machine registers contain parts of the program’s state, and I was saying that there are situations where you need to examine the state to understand the program’s behavior.
This seems like a fully general counter-argument against any self-representation: there is always a level you have to stop at, otherwise even modeling quarks and leptons is not good enough. As long as this level is well understood and well described, what’s the benefit of digging further?
Sure, but the point is that there are plenty of questions about oneself that aren’t necessarily answerable with only the source code. If I want to know “why am I in a bad mood this morning”, I can’t answer that simply by examining my genome. Though that’s admittedly a bad example, since the genome isn’t really like a computer program’s source code, so let me try another: if you want to know why a specific neural net failed in some specific discrimination task, it’s probably not enough to look at the code that defines how abstract neurons should behave and what the learning rules are like, you also need to examine the actual network—held in memory—that those rules produced.
Of course you might be capable of taking a snapshot of your internal state and then examining that, but that’s something quite different from doing a quine. And it means you’re not actually examining your current self, but rather a past version of it—something that probably wouldn’t matter for most purposes, but it might mattter for some.
This may well be a valid point in general, depending on the algorithm, but I am not sure that applies to a quine, which can only ask (and answer) one question. And it is certainly different from your original objection about machine registers and such.
What do you mean? Assuming that a quine can only answer a question about the source code (admittedly, the other commenters have pointed out that this assumption doesn’t necessarily hold), how does that make the point of “the source code alone isn’t enough to represent the whole system” inapplicable to quines?
I don’t follow. Machine registers contain parts of the program’s state, and I was saying that there are situations where you need to examine the state to understand the program’s behavior.