I've always thought bitcoin is backed by something...it's backed by the code. That is, it is backed by the fact that it's scarcity, verifiability, and its rules are absolute.

Trust is a fundamental for money. We trust that the piece of paper has value, not because it is backed by anything other than a government's blessing. Still, we trust it has SOME value, even when that value is diminishing due to inflation.

I know the mantra in bitcoin is, "Don't trust, verify," but in a way, we can trust that bitcoin is backed by these absolutes the code ensures. To me, this distinguishes it from any other form of money.