I came across the word doxastic (/dɒkˈsæstɪk/) today in Being Wrong – Adventures in the Margin of Error by Katryn Schulz. It means “pertaining to beliefs” and appears in the expression used in philosophy, ‘First Person Constraint on Doxastic Explanation’, or as Schulz terms it ”Cuz It’s True Constraint’. It means that we have only a limited number of ways to explain why we believe what we do.

We often believe things to be self-evidently true without necessarily being explain why or to provide reasons. For example, you might be convinced that your method or system for learning languages works and anybody who doesn’t agree just needs to be convinced of this. You might have invested a lot of time and money to develop and promote your system, so it’s in your interest to believe that the system works. You might not be consciously aware of this, but such things are often obvious in methods and systems developed by others.

Doxastic comes from the Greek δοξαστικ-ός (forming opinion, conjectural), from δοξαστής (conjecturer), from δοξάζ-ειν (to conjecture) [source].

The dox part, from the Greek δόξα (opinion, glory), also appears in such words as paradox – para comes from the Greek παρά (by the side of, beside, past, beyond), so it means ‘beyond belief’, and orthodox – ortho comes from the Greek ὀρθο- (straight, right), so it means ‘right belief’.

Dox is also internet slang for personal details (name, address, etc) that are visible online.