What does it mean to say you’re offended? If it means merely that you disagree with what I have said, then surely we have a right to offend. Surely the freedom of speech allows the expression of dissent.
Even if your disagreement includes any number of unpleasant emotions (embarrassment, shame, displeasure, irritation, annoyance, anger, distress, outrage, shock, fear, disappointment, frustration, envy, humiliation, guilt, sadness, anxiety, discomfort, disgust, a vague sense that my words are inappropriate or indecent, whatever the hell that means). Though often there is no awareness of disagreement; there is only the unpleasant emotion.
If ‘offend’ is the verb form of ‘offence’ as in ‘offences’, then to offend (also) is to do wrong. But, why, how is it wrong for me to express a view with which you disagree? Are you hurt by dissent? Harmed in any way? Disagreement aside, can words harm? Well, yes. Insults, in part, can cause psychological injury, which in turn may or may not cause physical distress. If I call Dick an idiot, and you disagree, do you feel hurt? Probably not. (Though I suppose it depends on whether Dick is your boss or your son.) But if I call you an idiot, you may feel hurt. Your blood pressure may rise. (Though that may depend on whether I’m your boss.) (Or your son.) So the real questions are do you have a right not to hurt in such a way, do I have a duty not to call you an idiot, is it wrong for me to do so?

Okay, are we talking about moral right, duty and wrong or legal right, duty, and wrong? Because it may be morally wrong to do X and yet we may want to retain the legal right to do so – some moral wrongs are ‘worth’ illegalizing. Is my calling you, or Dick, an idiot one of these?
We might want to distinguish between dissenting opinions (‘Dick is an idiot’) and insults (‘You are an idiot’) – after all, the latter are generally characterized by intent to harm whereas the former, generally, are not. But perhaps all we need do is distinguish on the basis of severity (rather than on the basis of kind). That would cover threats as well. (‘If you continue to be an idiot, I’m going to kill you.’) If I’m your mom (or otherwise important to you) (let’s just say) and you are young (or perhaps otherwise psychologically weak), then my calling you an idiot, especially on an hourly basis, is likely to cause permanent damage. You’ll never develop sufficient confidence or esteem to become a rocket scientist.
But surely at some point we are responsible for our psychological weaknesses. If you are an adult and such an idiot that you take to your bed at being called an idiot, or at hearing Dick called an idiot, surely the blame for such severe injury is not all mine. (And if instead you take up arms, then it is I who is the idiot.)
What if you don’t take to your bed? What if you continue to show up for work, but my continuous insults (or dissenting opinions?) just annoy the hell out of you all day, but so much so that you become exhausted by the effort not to take up arms against me and so become less exceptional at your job? Which means you don’t get the promotions or commissions that would’ve meant you could send your son, Dick, to college, so he could become a rocket scientist. Surely I’m in the wrong here. Should you therefore have legal as well as moral grounds for – something short of taking up arms? Even if – and perhaps especially if – I’m unaware that my remarks (jokes, taunts, full-page ads and billboards) are causing you such distress?
And surely we are responsible for our own opinions and beliefs. I know people say they were ‘born Catholic’ or whatever, but don’t they really mean they were born to Catholic parents? You can’t be born believing anything, let alone the tenets of Catholicism. Our opinions, our beliefs, values, attitudes – these are within our control, we voluntarily hold them.
Does it matter whether or not you actually are an idiot? Taking to your bed, or taking up arms would seem to prove its truth – but does truth put me wholly in the right?
Another consideration is the practical consequences. If we prohibit offense – my god, if every time I opened my mouth I had to be sure not to offend, not to in some way challenge every opinion, every belief, every value, every attitude, even if said opinions, beliefs, values, and attitudes are held unconsciously such that disagreement is bypassed and the unpleasant emotion is just a sort of psychological– well I don’t even know what to call that unawareness, that mental laziness, that apparently vehemently felt response whose cause is unknown to the one experiencing it, perhaps usually occurring with ‘offenses to one’s moral, religious, or patriotic sensibilities” (what the hell are ‘sensibilities’?) – well, I wouldn’t gotten past ‘my god’.
Which brings us to another consideration: the standard of reasonableness. If because of your unreasonable beliefs, you are offended by my expression of a reasonable opinion, doesn’t that put you in the wrong? As well as make you an idiot?
Good questions, and I broadly share the same answers. I do think there has to be a standard of respectful discourse, which will vary depending on the context. And one can always do better than “You are / Dick is an idiot”. What is an idiot anyway? One can always be more precise than that. But I agree that we must not let unreasonable beliefs determine our standards. If I am criticising you then I need to make sure that I am cautious, precise, and appropriately respectful in the way I express my criticisms (I say “appropriately” because one can also err by showing excessive respect). Ditto if I am criticising something that I know is dear to you, such as your religious beliefs. There should also be some kind of constructive purpose behind my criticism: we should not criticise just for the sake of it, even of we are right. But of those criteria are fulfilled and you still take offence, then that is your problem and must be seen as your problem.