Definition (Noun) The doctrine that all things tend toward ultimate good. In Context "The third choice regarding how to deal with life's unfortunate occurrences, and the way I recommend we live life, is to take what I call an agathist approach. An agathist is someone who believes that in the long run, even though bad things sometimes happen, everything will eventually work out for the best." Robert Puff Ph.D., Psychology Today, 2011