[ Simple/General/Accurate ]

Similar to the project management triad (cost, schedule, quality), there’s a theory of human behaviour, which is also a ‘pick two’ triad. 

Warren Thorngate stated it’s ‘impossible for a theory of social behaviour to be simultaneously simple, general, and accurate’. 

Simple theories usually can’t be generalised into different situations or contexts.  Or if you have a general theory, it tends to be very complex with lots of different pieces to it so that it can be applied generally.

This makes for a complicated truth.  The more general a simple theory, the less accurate it will be in predicting specifics (Gergen).