A valuable post on innovation and the mind-set of discovery:
Howard Gardner touched on this in his book Changing Minds.
Great innovators are not just smart, they are curious. They are rarely purists or polemicists, but are courageous enough to venture outside their domain.
[Gardner] is especially pessimistic on our capacity to change our own minds. We do not, on the whole, accept new facts and revise our theories. Rather, we interpret or disregard the new information to make it fit our theories. This is not a matter of IQ or lack of education. He points out that intellectuals are "particularly susceptible" to removing cognitive dissonance by "reinterpreting" the facts.(Further discussion of this problem here)
Among the forces that exacerbate this tendency to lock-in a theory are emotional commitment, public commitment (pride makes it hard to climb down when everyone is watching), and an absolutist personality. (Source)
Also relevant is David Gelernter's ideas about the mind and creativity.
I've always liked David Ogilvy's advice on finding big ideas:
Gelernter argues in The Muse in the Machine that creativity has three distinctive traits:
1. At base it "is the linking of ideas that are seemingly unrelated."
2. It is not an incremental process, rather inspiration comes as a bolt from the blue."
3. It occurs "in a state of unconcentration." Hence, "hard work does not pay. You can't achieve inspiration by concentrating hard, by putting your mind to it."
Big ideas come from the unconscious. This is true in art, in science, and in advertising. But your unconscious has to be well informed, or your idea will be irrelevant. Stuff your conscious mind with information, then unhook your rational thought process. You can help this process by going for a long walk, or taking a hot bath, or drinking half a pint of claret. Suddenly, if the telephone line from your unconscious is open, a big idea wells up within you.