Which Paranormal Phenomena can Scientists Investigate?

Some people don't believe in paranormal phenomena1 because they've been disproved by science. In some cases, this seems right to me. Dowsing, for instance, purports to be a reliable way to find water. If it's real, then it's consistent. And if it's consistent, it's falsifiable. You can take some dowsers out looking for water and see if they do better or worse than chance -- the effect size needn't be huge, but it has to exist. People have done roughly this multiple times, and the results don't look good for dowsers. Many other paranormal phenomena are like this. It should be easy to check if astrology is real: take a bunch of people, record their birthdays, and do some fancy psychometrics on them. Then, check if the Pisces are artsy and if the Geminis tell people to eat glue. If they don't, astrology will remain a form of entertainment which men pretend to enjoy around their girlfriends.2 If any sort of alternative medicine works, you should be able to measure how much it works.3 And…