'it will come back to you'

[robvalue]

Sorry to hear the magic thinking is still bugging you

The human mind seems very prone to superstition, I feel it creeping in sometimes and I have to police it and stamp it out.

There's no evidence that thinking about something will have any effect on its likelihood to happen, unless the thoughts lead you to actions which then facilitate it. And clearly no action you could do would facilitate random acts of carnage around the world to the degree that your companion was suggesting.

This kind of "just in case" thinking is another classic case of unfalsifiable claims. I can watch a horror movie, then at some time in the future I hear about a murder, and I can claim I caused it by thinking about murder. Trying to definitely prove me wrong would be impossible. However, there is absolutely no evidence to back up the claim so it amounts to an argument from ignorance.

Logic is God and logic permits you to think whatever you like If thinking affected reality directly, how would that even work? If someone is thinking the opposite to you, does reality do some sort of net calculation like with opposing forces? Woo is woo, and all woo is poo.

On the other hand, actual bad acts like kicking someone in the balls and running away often will indeed "come back to you" for obvious reasons. But just thinking about it will not.