Promises and permissibility

Here is an initially plausible idea:

• A promise can take an action that absent the promise is merely permissible and turn it into an action that is obligatory, but it cannot take an action that absent the promise is impermissible and turn it into an action that is obligatory.

I wanted to use this idea in an argument. But I have since come to a fairly definitive refutation. Suppose last year I promised you that today I would drive to Waco airport and sit for one minute on a bench and come back home. (Maybe we were playing some game, and this was the agreed-upon penalty for losing.) Plausibly, I am obligated to do so. But absent the promise, it would be impermissible for me to do it, because it would be pointless, and it is wrong to drive pointlessly, since each time one drives one (a) endangers human life and (b) contributes to environmental degradation.

Of course, a promise can’t take an action that is intrinsically wrong and make it obligatory.