This sounds like a copout. Lack of data doesn't imply equal plausibility. It means that you need to use other methods of reasoning. And people do this all the t

This sounds like a copout. Lack of data doesn't imply equal plausibility. It means that you need to use other methods of reasoning. And people do this all the time - it's not like every time you're faced with a new situation you go "Oh I don't have any data here, all of my options are equally good". No, what you do instead is use common sense, draw on experience, best judgment, mental heuristics etc. Those aren't as good as evidence based decision making but they surely beat throwing your hands in the air and saying that all of your options are the same.