That’s one way of seeing things, and I respect that viewpoint, but I disagree. I primarily view myself as my consciousness; everything else is secondary. How do you know you aren’t a brain in a vat?
One interpretation would be Many Worlds; that is, every quantum possibility is real in its own multiversal branch. So, to assign moral agency you would need to show that I chose the world I’m in now, over some other version of my life in which different choices were made. Although, I’m not certain you even need to go that far: I have no idea to what degree quantum randomness can actually affect our choices. But, in any case, that too would be out of our control.
If your perception is subject to failure, so to is the evidence, no matter how convincing. So yes, we act upon the assumption that reality exists. We both agree with this.
But that doesn’t mean it is true. And all I’m saying is for this very narrow point of what I care most about, Descartes does have a point. I care more about my mind than my foot. I mean, maybe you can think of a better way to frame the argument because I doubt you even disagree. If you have a gun and you are forced to shoot yourself anywhere on your body, would you choose your foot or your brain?
The better counter to me would be to prove external value. Would I sacrifice myself for someone else? If I believe reality doesn’t exist, the answer should presumably be no. If I believe reality does exist, the answer could be yes. Or alternatively, shooting myself in the foot suggests I believe in a causal relationship within reality towards shooting my brain and losing consciousness, which I shouldn’t necessarily believe.
But even then, it’s not that I disbelieve reality, it’s just that I can’t know for certain what’s real outside my mind, so there’s not really any contradiction between acting as if it is real and being uncertain if it is.
All this is doesn’t matter anyway: the point is less you could be a brain in a vat, but rather if you were a brain in a vat, would you be any less you? I don’t think so.
I have more evidence that the real world exists than I do that you are a thinking mind.
I have more evidence that I am a thinking mind than that I do that the real world exists. There’s no point arguing this point it won’t go anywhere.
The default is the assumption that the way the universe presents itself is the way it is.
Sure, but this is still an assumption I would need to agree to - though obviously a productive one - not necessarily true. The only thing I can know is my experience.
This isn’t particularly useful beyond explaining why I view my consciousness as primary and hands secondary or tertiary or something. The brain is tricky because again, I don’t know where it ends and my consciousness begins.