Apropos of my discussion of the paranormal and Marlborough Street, here (via Jerry Coyne) is an excerpt from an article by the Oxford chemist Peter Atkins:

One aspect of the paranormal versus real science should not go unremarked. As in other forms of obscurantist pursuit, such as religion, it is so easy to make time-wasting speculations. The paranormal is effectively unconstrained whimsicality. Original suggestions in real science emerge only after detailed study and the lengthy and often subtle process of testing whether current concepts are adequate. Only if all this hard work fails is a scientist justified in edging forward human understanding with a novel and possibly revolutionary idea. Real science is desperately hard work; the paranormal is almost entirely the fruit of armchair fantasizing. Real science is a regal application of the full power of human intellect; the paranormal is a prostitution of the brain. Worst of all, it wastes time and distorts the public’s vision of the scientific endeavour.

(Neither Coyne nor Atkins takes any prisoners.)

This seems perfectly true to me. And this is an aid in writing fiction that involves the paranormal: you get to make up the rules, and no one gets to tell you That’s really not how it works. You are the one doing the “armchair fantasizing”; you’re not advancing human understanding, but you may entertain a few people. The hero in Marlborough Street can find missing persons and occasionally dip into someone else’s mind; the heroine of Summit with great mental effort can force a person to change the way he thinks and acts. The only limitation is the limitation of all fiction: internal consistency.  It’s your fictional universe, but once you’ve set up its rules, you have to live by them.