> If you assume that the observer is described by quantum mechanics, then the Everett Interpretation is logically required to be true. If you want to argue for anything else, then you need to explain why you, the observer, are not described by our best scientific theory. That's a pretty good reason to take the theory seriously.

Arthur Conan Doyle notwithstanding, in science the truth is not arrived at by eliminating the alternatives. Science requires positive evidence -- absence of contrary evidence doesn't support a given outlook. Were this not true, Bigfoot and the Loch Ness monster would win acceptance through lack of contrary evidence.

How much science do you actually know? Because this sounds like philosophical twaddle that sounds good but makes no sense. If you seek positive proof of everything, then you can never generalize from experience at all. Every day is logically a new day, every object a new object and you have to rethink all of your assumptions at every step.

Science does not do this. Instead it tries to produce precise and general theories, tries to test them to destruction, and as they fail to be destroyed, assume them more and more broadly (while testing what we can in every detail that we can).

> ... the Everett Interpretation is logically required to be true.

In science, nothing ever becomes true, but some things become false. Philosopher David Hume summarized this outlook by saying, "No amount of observations of white swans can allow the inference that all swans are white, but the observation of a single black swan is sufficient to refute that conclusion."

Sorry, but you fail at basic logic. It is absolutely valid in science to ask, "What is the consequence if this theory applied to that system."

The consequence in quantum mechanics of a simple quantum mechanical experiment interacting with a complex quantum mechanical system is that the complex quantum mechanical system should be thrown into a superposition of quantum mechanical states that cannot meaningfully interact thanks to well-understood thermodynamic principles.

Whether this is an accurate description of the world is another question. However we've had several hundred years of spectacular success from assuming that the world is described by our best scientific theories, and then testing them as best we can - even though it means accepting things we cannot test at the moment. If we extend that principle to the present moment, we're forced to the Everett Interpretation. And if that turns out to be incorrect in some fundamental level, it is a basic fact that, to the extent that quantum mechanics does describe that system, the Everett Interpretation is true for it.

On that basis, and assuming we're still discussing physics, nothing is "logically required to be true." That's not science, it's philosophy.

You just failed at basic logic. I made a statement of the form, "If A, then B." This is a statement of math, not science, and as such can be true or false. (It is, in fact, true.)

The question of physics is whether the statement that quantum mechanics applies to both observer and observed is true. Nobody knows the answer to that. However the path that science has taken for centuries says that we should make that assumption as long as quantum mechanics remains our best theory, and we come up with no evidence against it applying to observers, and then find every way that we can to test it.