> What's the evidence that there is a brain or body in the first place, which is a big part of the original discussion?
I'll sidestep this by saying that for my purposes, reality is just a theorized model of what our senses perceive. If we don't trust our senses, then it's possible none of the things we perceive exist, but who cares? The things we perceive as our brain and body can be modeled to predict what we will perceive in the future.
> broadly speaking philosophy is where you stop having certain evidence for anything
That's not how I define philosophy, but I won't get into a semantic argument about what philosophy is. I also think saying things are "certain" is almost always a mistake. All I'll say is that if that if you define philosophy as eschewing evidence, then I'm happy to dismiss all of what you consider philosophy. If you aren't able to produce evidence (empirical or logical) for the statements you make, then all you're doing is stringing together words into grammatically-correct but meaningless sentences, which is not a skill I care about by itself.
I'm happy to say that I don't think all philosophers share your view that evidence is unnecessary, so there are many people who I would respect who I would also call philosophers.
> Once the body is assumed and our senses trusted,
I don't think we can assume that. Nor should we. Nor is there any value in doing so.
Let's temporarily assume the opposite: let's assume our senses are lying to us. If that's so, I'd argue that our senses lie to us in consistent, predictable manners. I can predict how my senses will lie to me in the future based on how they are lying to me now, and how they have lied to me in the past. If I choose to tell my fake body to let go of a fake ball, my senses will lie to me and tell me that the fake ball falls toward the fake earth. Every fake morning, my senses lie to me and tell me that the fake sun rises.
How would my situation differ if all this were real? If I really dropped a real ball and it really fell toward the real earth, would that be different? If a real sun rose in the real morning, how would that change my experience? In short, a falsehood so complete that it is completely indistinguishable from the truth is not meaningfully different from the truth. If I put my hand on a hot stove and sense pain, does it matter whether that pain is real or fake? I don't think it does.
> if you find solid evidence it'll be about how the brain differs (or not) from the rest of the body, not about the presence or absence of a mind or soul.
That's true, which is why minds and souls should be relegated to the fiction section of the bookstore, with ghosts, werewolves, elves, and all the other fictional things we don't sense with our senses. I'm not saying these things aren't fun to think about, they just shouldn't be considered as existent phenomena on which we base our beliefs and decisions.