Post hoc (a shortened form of post hoc, ergo propter hoc) is a logical fallacy in which one event is said to be the cause of a later event simply because it occurred earlier.
Post hoc is a fallacy because correlation does not equal causation. You cannot blame your friends for a rain delay just because every time they go with you to a ballgame it storms and play is delayed. Likewise, the fact that a pitcher bought new socks before he pitched a winning game does not mean that new socks cause a pitcher to throw faster.
The Latin expression post hoc, ergo propter hoc can be translated literally as "after this, therefore because of this." The concept can also be called faulty causation, the fallacy of false cause, arguing from succession alone or assumed causation.
Post Hoc Ergo Propter Hoc Logical Fallacy