Newspapers often have articles that say “Young children who sleep with the light on are much more likely to develop myopia in later life”. The public is often fooled into thinking that “sleeping with lights on” causes “myopia”. Correlation implies causation is a logical fallacy by which two events that occur together are prematurely claimed to have a cause-and-effect relationship.
Correlation alone does not necessarily imply causation. For example, two events might co-occur because they have a common cause, rather than because one causes the other. But when two events or changes do co-occur, and the time sequence is such that one always follows the other, people often infer that the first caused the second. Thus, inaccurate perception of correlation leads to inaccurate perception of cause and effect.
Judgments about correlation are fundamental to intelligence. For example, assumptions that worsening economic conditions lead to increased political support for an opposition party, that domestic problems may lead to foreign adventurism, that military government leads to unraveling of democratic institutions, or that negotiations are more successful when conducted from a position of strength are all based on intuitive judgments of correlation between these variables. In many cases these assumptions are correct, but they are seldom tested by systematic observation and statistical analysis.
Most of the time intelligence is based on prior-experience-based assumptions(common sense) about how systems and environments normally behave. The strength and weakness of a human mind is that it possess a great facility for invoking contradictory “laws” of behavior to explain, predict, or justify different actions occurring under similar circumstances. “Haste makes waste” and “He who hesitates is lost” are examples of inconsistent explanations and admonitions. They make great sense when used alone and leave us looking foolish when presented together. “Appeasement invites aggression” and “agreement is based upon compromise” are similarly contradictory expressions.
When confronted with such apparent contradictions, the natural defense is that “it all depends on. …” or “… is relative”. Recognizing the need for such qualifying statements is one of the differences between subconscious information processing and systematic, self-conscious analysis. Knowledgeable analysis might be identified by the ability to fill in the qualification; careful analysis by the frequency with which one remembers to do so.