People make decisions based on emotions (such as “common sense” and “belief”), and then rationalize them if they can. This is an ancient heuristic that has served us well by simplifying the making of decisions that either are simple (should I do something about the stranger who just moved into my personal space, or ignore him?) or unimportant (should I eat Cheerios or Wheaties?), or have consequences that are beyond any ability to predict (should I follow this wooly mammoth south, or turn east across this land bridge?).
In none of these situations would we be better off making a list of pros and cons before making the decision. Rational decisions require attention, and when the problem is simple or unimportant or beyond our ken, that scarce resource is better spent elsewhere.
If you are not a trial lawyer, please bear with me for seven paragraphs.