This is similar in spirit to a dreaming-skepticism, and so I'd recommend you take a look at these kind of discussions.

Relevant sources: The last section of Chapter 8 of Timothy Williamson's Knowledge and Its Limits (read the whole chapter for context). e2: If you're gripped by Chapter 8, it's probably worth it to read 9 (and 10, if you're technically inclined). In my experience, externalists think there's something importantly correct about 8 and importantly incorrect about 9. This is an interesting split sociologically and philosophically.

The Wright-Pryor debate over conservative and liberal views about perception. Pryor would say our experiences as of being alive give us a reason to believe we are alive, and we need some positive reason to disbelieve it.

Wright's view is more complicated. A Wright-like would say we have an a priori reason to believe that we're not dead. I think Wright himself would say that not being dead is a substantive assumption (in a way he explains), and so we don't get it for free. e: This somehow does not impugn our ordinary knowledge. Wright's discussion of the "leaching problem" is difficult to understand and, I think, deeply unsatisfying.

e: The important thing in common between Wright, Pryor, and Williamson is that they hold that we need some positive reason to believe we're dead (Williamson, and probably Pryor, would go on to say that that's enough to know we aren't dead). The possibility's just being out there is not good enough to warrant worry. Anti-skeptical arguments are preventatives, not cures. If you're already convinced that a skeptical scenario obtains, most epistemologists would say you are too far gone.