Hurkyl said:
Yes. That's all "rationalism" and "empiricism" are -- epistemological positions.
Not when the knowledge in question is about "what exists." This is the point of contact between epistemology and ontology, and it is exactly the place where CI and MWI differ. They just don't differ anywhere else. They certainly don't differ in the issue of how to know if a theory makes correct predictions or not, and they don't differ in the issue of whether or not observers and theorists need to confer on a joint agreement of what is a good theory. So they simply don't differ in any of the ways in which scientific knowledge is judged or obtained, except one: they differ on the issue of what constitutes true knowledge about what exists.
Certainly not, not to the empiricist. Your claim here is, categorically, that how a mathematical entity depends on a variable t, makes a one-to-one claim on how some system behaves with the experiential and measurable concept of time. That just isn't true. You are missing that we are already affixing an interpretation to a physical theory that the parameter t in the theory corresponds to the empirically measurable concept of time. But it is not a necessary part of any theory that we must fail to distinguish between an experimental measure and a parameter in the theory (note for example that t is not an operator of quantum mechanics). It is part of the judgement of the value of the theory to connect that variable t to the empirical observation of experienced time, but only in the same empirical context that all theories are judged. No one ever says "I criticize your interpretation that t is time on the basis that it just doesn't seem like time to me", no, any criticism of that interpretation must be based on empirical comparisons of how the parameter t acts under experimental conditions. But we already know that the t that appears in the Schroedinger equation will not correspond to any experiential version of time if t is small enough, so the entire idea that "t" in QM is a continuous reflection of real time is simply false.
Ad hoc is necessary, but bad. The more ad-hoc a theory is, the less its ability is to make precise predictions, which in turn diminishes the value of any evidence favoring the theory.
MWI is just as ad hoc, but the ad hoc nature comes at a different level in the goals of the theory. CI adds an ad hoc physical postulate that some mysterious process, not covered by the theory, chooses which outcome we actually experience, MWI adds an ad hoc metaphysical postulate (as you did above) that our particular individual experience is a question that physics should not be interested in. CI sees that as cheating-- it's not surprising that greater unification can be achieved by allowing ourselves to cheat on what a theory should describe (rather than on how it should describe it, that was Einstein's objection about dice).
No. MWI is motivated by the question "Can a mathematically unified method explain what I perceive?"
It can't be that, because it fails to do that. Also, note that CI is just as
mathematically unified as MWI. It has to be, it's
all the same mathematics. MWI is not content with mathematical unification, it wants ontological unification. And it can only accomplish it by dodging the question of why I perceive what I perceive. I still haven't seen your answer to that. Your scenario doesn't answer it, because we don't have an observer getting <heads,tails>, we have a bundle of perceptions connected with the sentient being I'll call observer1, and a bundle of perceptions (according to MWI) connected with sentient being observer2, whose perceptions do not overlap and they do not perceive each other. So what you'd have to say is, you have <observer1,observer2> reporting <heads,tails>. If you do that, the mathematical description is entirely unitary, but you have no way to account for why it did not come out <observer1,observer2><tails,heads>. All you could say is that you don't care about the difference there-- but try telling that to observer1 if "heads" means he loses his.
I think you mean some sort of Platonism, rather than rationalism.
Platonism is quite a bit different from the way MWI is normally expressed. Indeed, I would have no problem with MWI as a form of Platonism, that is the sense in which MWI makes reasonable claims. The key difference is that Platonism draws a distinction between what is physically real and what is abstractly real. If people want to imagine that the many worlds are abstractly real, as some form of perfect concepts, I would have no issue with them other than being a bit idealistic. It is the claim on
physical reality that I feel should require empirical demonstration. When someone can empirically demonstrate the existence of many worlds, only then would I find it appropriate for us to conclude that they are
physically real.
Formally, at least, theories are syntax and truth is semantics, there's no if's, and's, or but's about it. And I'm enough of a formalist to believe that anyone who claims otherwise really just hasn't learned to mentally separate the ideas of "theory" versus "interpretation".
I completely agree, that was the flavor of Godel's proof-- syntax and semantics can never be the same thing in any formal system rich enough to be suitable for our purposes. Indeed that is my entire issue with how MWI is normally expressed-- it improperly crosses that dividing line, mistaking a syntactic interpretation for a semantic one. That's also the place where ontology creeps in.
I strongly disagree. It is very, very difficult to consider an empirical "truth" without having first filtered it through one's intellect. I would be so bold to claim it impossible to do so completely.
That's true, it's the bugbear of formal empiricism that brainless entities can't do it. All the same, it is pretty clear when a consistency of perception has been identified. That's why reading of pointers can be done by almost anyone, but predicting those readings can be done by rather few. The rationalistic perspective about what is true knowledge regarding what exists is quite elitist, and suffers the flaw that a much more intelligent species than we will likely form a completely different view, one that we simply cannot understand any better than most plumbers understand string theory. Yet the plumber knows what he experiences, so the empiricist version is a more accessible ideal about what constitutes truth. Empiricism also avoids the troubling "truth is only as good as your current theory" problem that dogs rationalism.
Still, I grant you that neither rationalism nor empiricism can make a self-contained case, and that's probably why we need a combination to do science. Perhaps we have more to learn from the tension between the CI and the MWI, than we have to learn by marrying one or the other. But I completely agree with
Fredrik that you are mischaracterizing CI when you say that it adopts essentially supernatural claims about the ontology of collapse-- instead, CI adopts a solipsistic perspective on collapse, it merely accepts collapse as real on the basis that we experience it, and unitarity as unreal on the basis that we do not experience it. CI takes no other position on the matter, there is no sense that "a miracle happens" when collapse occurs-- instead, collapse
is what happens, the two are exactly the same concept in every way. That's why I said that unitary evolution is not a behavior at all in CI, it is just the language of how to predict, statistically, the next behavior, the next collapse. There is nothing in the empirical meaning of our word "behavior" that is not also in the word "collapse," so there is no need to attribute any mystical or miraculous elements to the latter word.
