Then we can pardon Bostrom for not taking them into account.

When pondering the possibilities where we live given lack of grand unified theory 'of everything', you can't assume your physical intuitions hold true. In fact you should assume the opposite. The MWI is just an example of how philosophical argument that looks entirely invariable admits defeat from possible physics, in a way in which the mathematics - which philosophy mimics - does not. That means validity of argument requires validity of intuitions, which are reasonably very unlikely to be valid in any grand sense. There's also historical example: a lot of philosophers assuming Euclidean geometry is the only logically possible kind of geometry, without even noticing that they are making such assumption, up until mathematicians came up with alternative.

What? Could you write this more clearly, I have no idea what you're trying to say.

You assume that the probability of being among either group depends to number of yous within that group (rather than something entirely different), to do anthropic reasoning beyond tautological 'we can't observe universes where we can't be alive'. In my opinion this is a case of wild guess over unknowns, totally false precision.

I came up with a clearer example of how something totally different may actually make a lot more sense: Solomonoff induction on codes that model various universes. A model of the universe outputting the data matching your internal self-perception must not only contain yourself, but must include the code that finds yourself within that model, so that output begins with sense data. It is then clear that the code that picks one of yous out of a model full of all sorts of simulations may easily be larger than the code that picks you out of the world where there is just one you, but the number of various others is much smaller.

I'm not arguing that Bostrom is bad for a philosopher. I am outlining how in philosophy you just make all sorts of assumptions that you don't notice are wild guesses, and how the field is basically built on false precision. I.e. you assume that the probability of being within some huge set full of yous and non-yours is independent of number of non-yous, which is just a wild guess. Connect together half a dozen implicit wild guesses with likelihood of correctness of overly generous 1 in 100 each , and we're speaking of probability of correctness in the range of 10^-12 . Philosophy is generally like this.

I believe this falls under Nick Szabo's complaint about false precision.

Also, a paper by Steven Weinberg on usefulness of philosophy.

It seems to me that funding philosophical works in this field may actually be actively harmful, due to establishment of such false precision and prejudices. It's like funding 'embracing bias, imprecision, and making your mind up before checking where the mathematics will lead you'.

If even Newton looks this foolish, what hope can the rest of us have? No, the suggestion 'would this make me look foolish in 100 years?' does us no good in practice.

That's the whole point: very low probability of being right. There's a crucial difference: the methods Newton employed managed to achieve a non-zero (and not negligible) truth finding rate. So he made something that does not look silly. Even with this, most of stuff was quite seriously wrong.