[PHI 1000] One's modus ponens is another's modus tollens

Here is a simple argument for free will:

1. If we are morally responsible for what we do, then we have free will.
2. We are morally responsible for what we do.
3. (Therefore) We have free will.

In response, a hard determinist could argue as follows:

1. We have free will only if we are morally responsible for what we do.
2. We are not morally responsible for what we do.
3. (Therefore) We don't have free will.

Both arguments are valid. Which do you find more convincing?