The degree to which you believe the guy will make good on his promise to always buy snail tails in exchange for water is the degree to which you believe snail tails are backed by water. We can be pretty sure the US government will generally make good on its promise to take US dollars in exchange for not prosecuting you for non-payment of taxes.

>I reject your definition of "intrinsic value". Sounds sorta' like "regular value" to me.

I don't like the term 'intrinsic value' at all, since it sounds like it's suggesting some type of absolute value, which I don't think very many people (at least, not the ones having these conversations) really believe exists. I think the way they mean it is more in line with the way I defined it, to distinguish between something some people buy for its own sake versus something people only buy so they can trade it away to someone else, who is in turn only buying it so he can again trade it away. The latter still clearly has value to those people who take it in trade, and 'intrinsic value' is a convenient term to distinguish between the two.