«Yes. The many-worlds theory as a response to fine-tuning seems desperate and stupid and suffers from the defects you mention.»
Correct me if I am wrong but I don’t think the many-worlds theory works as a response to fine-tuning, since the fundamental constants are the same in all the worlds. I think you are referring to the multiverse, which is a different concept, a set of gazillion universes where each universe has a different set of values for the fundamental constants (take that, Ockham!). Not that this solves the fine-tuning problem (the multiverse mechanism must be fine-tuned to produce valid universes) but, hey, when you are trying not to go where the evidence leads, anything goes.
«However, Sean Carroll claims that the many-worlds theory initially proposed by Everett was not a response to a theological problem, but is actually the most straightforward implication of the equations. »
I don’ t think there is a straightforward implication of the questions but the many-worlds interpretation is a valid interpretation according to science (but not without its scientific problems https://www.youtube.com/watch?v=_42skzOHjtA).
However, as a metaphysics, it is a very extravagant interpretation and other interpretations should be preferred for the time being, at least while we don’t have new data.
Have I said «for the time being»? Yes, this is what science is: a provisional knowledge. For every set of data, there are infinite theories that meet the data. We prefer the «prettiest» theory: the one with more explanatory power and more simplicity, for example. Of course, future data can disprove this «pretty» theory and point to an «uglier» theory, but we cannot suspend judgement waiting for a future refutation for every theory, refutation that may or may not arrive. If we did that, science books would be blank. We wouldn’t accept any theory because future data could disprove it.
It’s obvious that the the Copenhagen interpretation is much superior to the many-worlds interpretation. What is the problem them? Why don’t we accept it «for the time being» as any other theory? Why do we decide to suspend judgement and allow tens of different interpretations to be equally valid? (some of then quite bizarre, such as the many-world interpretation or the many-minds interpretation). Why does this double standard exist? It is because Copenhagen interpretation goes against naturalism, that’s why (the same as fine-tuning, see above).
Not that this should be a problem: in fact there is much philosophical and scientific evidence that consciousness is not physical, most of it unrelated to quantum theory. But all this evidence is forgotten or disregarded, because, hey, when you are trying not to go where the evidence leads, anything goes.
Geneticist Richard Lewontin said it best:
“Our willingness to accept scientific claims that are against common sense is the key to an understanding of the real struggle between science and the supernatural. We take the side of science in spite of the patent absurdity of some of its constructs, in spite of its failure to fulfill many of its extravagant promises of health and life, in spite of the tolerance of the scientific community for unsubstantiated just-so stories, because we have a prior commitment, a commitment to materialism.
It is not that the methods and institutions of science somehow compel us to accept a material explanation of the phenomenal world, but, on the contrary, that we are forced by our a priori adherence to material causes to create an apparatus of investigation and a set of concepts that produce material explanations, no matter how counter-intuitive, no matter how mystifying to the uninitiated. Moreover, that materialism is absolute, for we cannot allow a Divine Foot in the door.”