What is the benefit of spending time on such a contrived scenario? This is the ethicist's version of "assume a spherical cow".
In actual reality you will never have any certainty about the outcomes of interactions like these. All you have control over is whether or not you hurt the person in front of you.
In actual reality you will never have any certainty about the outcomes of interactions like these. All you have control over is whether or not you hurt the person in front of you.