Yesterday I was talking to Lucy, my nine year old daughter, about irony and sarcasm and the difference between them. We looked up both words in the Collins Cobuild Dictionary:
Irony is a subtle form of humour which involves saying things that you do not mean.
Sarcasm is speech or writing which actually means the opposite of what you mean to say. Sarcasm is usually intended to mock or insult someone.
I mostly avoid sarcasm but I have a fondness for irony — a fondness that people of some other nationalities seem to lack. The dictionary can mark out a border between irony and sarcasm, with mockery and insult kept on one side. But there is contested territory where irony and sarcasm meet. Mockery and insult are feelings, not measurable commodities.
Today, I read that a research team from Haifa University has located the parts of the brain that comprehend sarcasm, according to a BBC News report.