The phrase "discernible reason" means having a clear or noticeable explanation or cause for something. It refers to being able to see or understand the logic behind a situation or decision. Full definition
Unhappily, the UMD Passport system that would have allowed PSP owners to transfer their games to Vita hasn't made it out of Japan, meaning that once again Sony is missing a trick by removing backwards compatibility with a very popular system for little discernible reason. (cubedgamers.com)
The Christian tradition is full of those who have suffered death and persecution as a result of their faith and, in some cases, for no discernible reason whatsoever. (relevantmagazine.com)
Has had several fake movie fights and possesses one of the most important attributes for a successful fighter: he's extremely confident for no discernible reason. (sbnation.com)