Thinking new thoughts (as opposed to cached thoughts) is risky behavior, if e.g. it makes you a crank, but I don't think it can properly be called a bias.

Most thoughts are cached thoughts, or put together from other cached thoughts like Tinkertoys; most new ideas are heard from others rather than invented. Genuinely new thoughts are rare, even if they're less rare in the young than the old. To my mind their rarity increases their value: the ability to invent new thoughts is precious.

In writing fiction I've practiced techniques that reliably induce creativity: brainstorming, freewriting, random association, and so on. These are non-methodical in character; they're not processes you can use to produce a result, but processes that put you in a state that allows you to produce the result. They are basically irrational. Does that mean creativity is a failure mode of rationality, or are there techniques a rationalist can use to produce new thoughts?