The fact that a large animal is attacking me would give me both permission and reason to kill the animal. On the basis of cases like that, one might hypothesize that permissions to ϕ come from particularly strong reasons to ϕ.
But there are cases where things are quite different. There is an inexpensive watch on a shelf beside me that I am permitted to destroy. What gives me that permission? It is that I own it. But the very thing that gives me permission, my ownership, also gives me a reason not to smash it. So sometimes the same feature of reality that makes ϕing permissible is also a reason against ϕing.
This is a bit odd. For if it were impermissible to destroy the watch, that would be a conclusive reason against the smashing. So it seems that my ownership moves me from having a conclusive reason against smashing to not having a conclusive reason against smashing. Yet it does that while at the same time being a reason not to smash. Interesting.
I suspect there may be an argument against utilitarianism somewhere in the vicinity.