In all the classic texts on equities derivatives, there is an assumption of the risk-free rate r. We can immediately dismiss the concept of a fixed rate; all interest rates are variable (and martingale?) in reality.
But also, as is more apparent in the current crisis, currency has a cost of carry, and no counterparty is risk-free (witness the lowering of sovereign credit ratings). On the other hand, there is almost always inflation; in growth periods the inflation is driven by high base rates, and in recession it is driven by quantitative easing.
Can we say, then, that the risk-free rate is in fact only ever lower than inflation, and that the rate is never fixed?
If you disagree, in what circumstances is the risk-free rate higher than inflation?
Edit: answers appreciated, but the crux of the issue is this: how can a rate be actually risk-free if it is above inflation? That implies there is a resource which yields increasing value with no risk; but no commodity permits this? Where is the disconnect?