Consequentialism is an ethical theory that judges whether or not something is right by what its consequences are. For instance, most people would agree that lying is wrong. But if telling a lie would help save a person’s life, consequentialism says it’s the right thing to do.
Two examples of consequentialism are utilitarianism and hedonism. Utilitarianism judges consequences by a “greatest good for the greatest number” standard. Hedonism, on the other hand, says something is “good” if the consequence produces pleasure or avoids pain.
Consequentialism is sometimes criticized because it can be difficult, or even impossible, to know what the result of an action will be ahead of time. Indeed, no one can know the future with certainty. Also, in certain situations, consequentialism can lead to decisions that are objectionable, even though the consequences are arguably good.
For example, let’s suppose economists could prove that the world economy would be stronger, and that most people would be happier, healthier, and wealthier, if we just enslaved 2% of the population. Although the majority of people would benefit from this idea, most would never agree to it. However, when judging the idea solely on its results, as classic consequentialism does, then “the end justifies the means.”