The phrase “the end justifies the means” is used to suggest that any activity, whether or not that activity could be considered ethically or morally bad, is worth doing so long as a desired end result is achieved.
The origins of the phrase go back to consequentialism. Consequentialism is a type of normative ethical theory. In its purest form, consequentialism holds that the moral quality of an action is completely determined by its consequences. Therefore, according to consequentialist theory, the end justifies the means in all circumstances.
Of course, for most of us this theory is difficult to square with our desire to get along with, and care for, other people; especially those within our immediate family, community, or friend group. Most of us feel that in many situations the end does not justify the means. That said, there are plenty of modern-day and historical examples, several of which we will touch upon below, in which this moral pull is ignored, and the ends of bad behavior win out.