Not necessarily. I'm not suggesting to throw reason and common sense all along.

I'm just suggesting that, in the absence of scientific evidence, you can rely on plausible intuition and stories.

As an example, suppose you noticed that whenever you don't sleep well you are more forgetful. And suppose there were no studies, research, whatsoever linking sleep to Alzheimer's (like the one posted earlier: https://news.ycombinator.com/item?id=24365546). Then your own experiences which could also be echoed by others, are enough to make this a hypothesis worth considering, and act upon it (=pay attention to your sleep quality) until there are rigorous scientific studies confirming (or disproving) it.