What is critical thinking?

Considering each word of the concept separately, “critical” is generally understood as analyzing and outlining problems (connected to the word “criticize”), or alternatively can mean extremely important (such as “critical infrastructure”). “Thinking” refers to the brain's memory access, usually consciously, rather than subconscious. Putting these 2 terms together should give a fairly straight forward understanding of the concept of Critical Thinking as; important conscious analisis and distinguishment of problems. 

In order to determine problems in any given circumstances using critical thinking, generally the best method is to take an unbiased objective perspective and use rationality to evaluate which components cause a less preferable outcome. Understanding cause and effect is “critical” for determining the cause of a variation to an outcome, such as a variation that is less preferable. 

In complex circumstances, many components are involved, so understanding the cause of an alteration of outcome, involves perspective isolation of particular components and their cause and effect. Once this objective perspective has been taken of an understanding of the isolated component which causes the less preferable outcome (or problem), alteration to that particular component can be intuited for a more preferable outcome (or solution). 

The alternative to critical thinking could be considered; being emotionally reactive or using intuition. Since it is an alternative to critical thinking, basically by definition it would be a method without using rationality and understanding of cause and effect. Using intuition is more of a concept of subconscious memory access which is less effective and accurate for complex scenarios. 

This overall concept of thinking in a way of being critical, by analyzing problems through the process of objectively determining the particular cause of such problems and consecutively determining solutions, can be applied to such a vast array of situations in one's life, that it should suitably be considered vitally important, or critical.