I think of it as the cognitive machinery which converts an input of questions/problems/issues into an output of answers/solutions/actions.
The quality of the machinery is measured by the success of the outputs.
One of the characteristics of the process is its abstraction ie the capacity to think of practical problems in abstract ways. This allows you to manipulate the problem, approaching it from different angles and trying out different possible solutions - all done inside your head.
How that turns into proclamations like 'The average IQ of Americans is 102.3' is beyond my machinery's capacity to understand.