{ 1 } - Don't believe that something is your duty without acting to do it.
{ 2 } - Don't combine believing that you ought to do A now with not acting to do A.
{ 3 } - If you believe that you ought to do A, then you ought to do A.

This can imply absurdities. Suppose that Ima believes that he ought to commit mass murder; then he ought to do it! The principle tells us, implausibly, that whatever we take to be our duty actually is our duty -- we can't be in error about what we ought to do.

We can also give cases where this principle has self-contradictory implications.