On the limits of rationality given flawed minds —
There is some fraction of the human species that suffers from florid delusions, due to schizophrenia, paraphrenia, mania, or other mental illnesses. Let's call this fraction D. By a self-sampling assumption, any person has a D chance of being a person who is suffering from delusions. D is markedly greater than one in seven billion, since delusional disorders are reported; there is at least one living human suffering from delusions.
Given any sufficiently interesting set of priors, there are some possible beliefs that have a less than D chance of being true. For instance, Ptolemaic geocentrism seems to me to have a less than D chance of being true. So does the assertion "space aliens are intervening in my life to cause me suffering as an experiment."
If I believe that a belief B has a < D chance of being true, and then I receive what I think is strong evidence supporting B, how can I distinguish the cases "B is true, despite my previous belief that it is quite unlikely" and "I have developed a delusional disorder, despite delusional disorders being quite rare"?
The relevant number is probably not D (the fraction of people who suffer from delusions) but a smaller number D0 (the fraction of people who suffer from this particular kind of delusion). In fact, not D0 but the probably-larger-in-this-context number D1 (the fraction of people in situations like yours before this happened who suffer from the particular delusion in question).
On the other hand, something like the original D is also relevant: the fraction of people-like-you whose reasoning processes are disturbed in a way that would make you unable to evaluat...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one.
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.