In
attribution theory[?], the
Fundamental attribution error is defined as attributing a bad act to the other
person ("he forgot my birthday, therefore he is a bad man") rather than to the person's
circumstances. Applied to oneself, it works in reverse. We tend to attribute our own bad acts to the the particular circumstances, not to our personalities: "I forgot your birthday, but I'm not a forgetful person, it was just that it was Monday and I was busy at the office and I had a headache". People make this error in a very consistent way.
Compare to ad hominem arguments.