If you think Saoirse Ronan is right about women's safety, then you agree sex matters.

You can't have it both ways.

When I was 18 I used to drive my parent’s car to parties. Living rurally, these hour-long trips were my only chance of a social life at a time when, like all teenagers, I desperately craved one. I would have to drive myself back, alone, through winding country lanes, in the middle of the night.

On the passenger seat, I carried a weapon of self defence: a…