perfidy

I've always thought that good intentions were, in general, given too much credit. But this goes a little further, and rings true to me. Especially this:

"When I examine my conscience, I perceive that the worst intentions were typically those times where I was trying hardest to signal to myself and to others that my intentions were good, pure, blameless. That was when I was most deeply in thrall to pride."

Good intentions? Not so

from Bruce Charlton's Miscellany