What have you changed your mind about?
And, paradoxically, one of the first ones I come across is one that I like a lot, but I don't think is easily digestible to non-scientists, and indeed, runs counter to much of what I've been writing. Irene Pepperberg talks about the the importance of doing more than hypothesis testing.
As to her first point, my favourite version of that is from Niko Tinbergen, who, in one of his most famous papers, wrote:
Contempt for simple observation is a lethal trait in any science(.)As for Pepperberg's third point: strong inference, baby.
I'm going to be reading this page a lot, methinks. Fantastic.