I would say that most superstitions are formed by noticing that two things in one's past experience were related in some way and assuming that the relationship

I would say that most superstitions are formed by noticing that two things in one's past experience were related in some way and assuming that the relationship will continue in the future. That's correlation. Of course, some people only notice data that fit their preconceived perspective, and some people have received superstitions based entirely on the words of others. I'm sure there are other exceptions too. But in my mind, the conceptual framework for understanding irrational thought is that we have these brains that are amazing pattern matching machines and we don't know how to turn them off. Once we've noticed a pattern, most of us assume it's a real correlation, and no matter how many exceptions to the pattern we see, we don't know how to stop believing.