@BigT: I tucked “proof” in there because proving the harm of a nose punch is easy and uncontroversial, but the essentiality of that proof is implicit in the motto. Punches in the nose are by definition harmful. QED before we begin.
But for passing an infection, even if an all-knowing Oracle knows the doer really did pass the infection to the doee, as long as the doer can semi-plausibly assert “No, you caught it from somebody else”, the doer will still consider that they didn’t harm the doee. Strictly speaking, the motto neatly sidesteps the question of “who decides what’s harm?”. But the rhetorical construction strongly suggests the decision of “what is harm?” lies largely (solely?) in the eyes of the doer.
@Joey_P: That’s exactly what it means. And that demonstrates to anyone paying the slightest attention just how friggin’ stupid/dangerous it is as a slogan or worse yet, as an actual worldview.
Not wanting to hijack this thread any further with a discussion of what libertarianism means, Here’s my post in a recent thread debating exactly that topic: