"I think there's a difference between (a) offending people fo..." — Philip Pullman quote meaning

I think there's a difference between (a) offending people for its own sake, which I don't necessarily want to do, because some people are good and decent and it would be unkind to upset them simply to indulge my own self-importance, and (b) challenging their prejudices, their preconceptions, or their comfortable assumptions. I'm very happy to do that. But we need to be on our guard when people say they're offended. No one actually has the right to go through life without being offended. Some people think they can say "such-and-such offends me" and that will stop the "offensive" words or behaviour and force the "offender" to apologise. I'm very much against that tactic. No one should be able to shut down discussion by making their feelings more important than the search for truth. If such people are offended, they should put up with it.