Many sources of writing advice, from Orson Scott Card on down, offer some form of this suggestion: “Don’t stop at your first idea. It’s a cliche. Keep thinking. Your second idea, third idea, fourth — those are where you’ll find the interesting and novel.”
This advice has some practical merit to it. Keep thinking, keep improving; beware of easy answers.
However, there’s nothing unique about your first answer, nor your fourth. Whatever cliches and tired ideas you’ve absorbed from your media consumption, they’re still in your brain after you’ve produced the first six variants of an idea. If your ideas get better through iteration, it’s not because “First Ideas Are Trash,” but because by idea #3 you’ve spent more time thinking about the issue.
Still, I classify this advice under “complete bunkum” for one reason: it’s a straight-up example of the availability heuristic. This cognitive bias occurs because the human brain grabs onto the memorable and striking events, and forgets the brief and irrelevant. You remember the one time you foretold the future, but forget the thousand other intuitions that never came true.
How is the availability heuristic relevant here? When a new idea flits through your head, you’re not going to latch onto it unless it seems better than your old idea. Any new idea you remember is, by definition, better than your old idea.
Go ahead and find a better idea than your first one. But don’t go teaching new writers a truism as if it’s valuable insight.