EDIT: Let’s cool it with the downvotes, dudes. We’re not out to cut funding to your black hole detection chamber or revoke the degrees of chiropractors just because a couple of us don’t believe in it, okay? Chill out, participate with the prompt and continue with having a nice day. I’m sure almost everybody has something to add.
It’s a statistical science. While other branches can be all like “splitting atoms will definitely give you an energetic reaction” psychology is like "this helps in 60% of cases so we’re gonna try it on you ".
To be fair here, technically throwing neutrons at matter has only some probability of causing it to fission, and statistics tells us how many do. It’s just that there are so many more neutrons and nuclei than there are people, so we can say with statistical confidence that under such and such conditions, y will occur when x happens.
Not that different. Just more samples and observations.