The U. S. compares the consequences of invading a fractious Central-American nation versus dealing with it in another fashion. We must compare to stay alive, and we compare frequently so as to live better, though sometimes we make life worse by comparing too often. At the core of every evaluation lies the process of comparison. And the heart of every comparison is a consideration of the benefits and costs of each alternative being considered. Cost-benefit analysis is the formal apparatus for comparing alternatives.
Economists like to refer to their discipline as the science of choice.
But choice can also be seen more simply, as just the selection among alternatives without any explicit statement in advance of the resources available to you. Values, ethics, creation of precedents, and complex social balances must sometimes enter into the decisionmaking along with the monetary costs and benefits. Though the analytic framework of cost-benefit thinking suits a wide variety of situations, sometimes it produces results that are foolish or worse. Some decisions are simply a matter of taste, and trying to apply cost-benefit analysis obviously would be wacky. In a love relationship the other person might regard the analysis as inappropriate.