> I’ve always found the denial of the existence of experiential consciousness to be kind of funny. If you removed all my senses and put my brain in a vat to keep it alive, what would be left? As far as my brain is concerned, consciousness is the _only_ thing for which I can be definitively certain of its existence.

Yes exactly, it is the thing that is most familiar to us, most accessible, and the only thing of which we can be certain. Descartes in his Meditations went down this path, starting with that foundation.

But I don't think you need to land on solipsism, because we don't have to believe only those things which can be proved. To me, it seems a reasonable hypothesis to suppose there are other consciousnesses. For an experimental line of thinking that leads to that conclusion, I would recommend the aforementioned Meditations.

Many are tempted to think that the physical world is the certain thing that we have, missing the fact that we experience the physical world, and so it is experience that we have access to, not the physical world itself. That I am conscious and have experiences of such and such is the thing I am most certain of. Whether there are physical things that correspond to those experiences is an extrapolation.