A word for something that is immoral, but beneficial?

Is there a word for something that is immoral or unethical, but must be done since it is beneficial. For example you would use the word to describe something like this, "we must kill those who misbehave so that we may maintain peace and prosperity in the country". Or another good example is Dexter from the TV show Dexter, he kills people, but he kills them because they are bad people.

Solution 1:

This is called a necessary evil (also known as the lesser of two evils). It is used to refer to a choice that is bad, but preferable to the alternative choice that is much worse.

In your example, you have 2 choices:

1. Kill people who are violent criminals.
2. Do not kill those violent criminals and allow them to continue to harm society.

Killing violent criminals could be considered immoral, but it can be considered a necessary evil since the alternative of letting them live and continue to harm society is worse.

There are even a lot of references on the Internet to Dexter as a "necessary evil".

Solution 2:

A term worth considering is utilitarian (Merriam Webster)

1. of or relating to or advocating utilitarianism

where utilitarianism is (wikipedia)

a theory in normative ethics holding that the proper course of action is the one that maximizes utility, usually defined as maximizing total benefit and reducing suffering or the negatives.

In other words, utilitarianism is balancing the benefits against any negative associations and acting accordingly (the benefits outweigh the moral costs).

You could also consider immoralistic (Wiktionary)

related to immoralism or an advocate of immoralism

where immoralism is (Wiktionary)

A philosophy that does not accept moral principles

The term comes up in discussions of Plato's The Republic, where the primary topic is justice and its benefits, but includes arguments on defining morality as well. Thrasymachus argues that true justice and ethics is actually contrary to the principles of justice and morality that others hold, saying they are what is in the interest of the stronger.

Sparks Notes provides this in its analysis:

As Thrasymachus makes clear, justice is not universally assumed to be beneficial. For as long as there has been ethical thought, there have been immoralists, people who think that it is better to look out for your own interest than to follow rules of right and wrong.

Based on this, you might give thought to the formation Thrasymachian to describe the concept submitted by Thrasymachus, as summarized by that last sentence.

An immoralistic or Thrasymachian attitude is a selfish one, and it assumes the actor is superior to others and entitled to look after their self-interest before the interest of others.

Solution 3:

Machiavellian: (from TFD)

or pertaining to Machiavelli. - being or acting in accordance with the principles of government analyzed in Machiavelli's The Prince, in which political expediency is placed above morality.

• Scholars often note that Machiavelli glorifies instrumentality in statebuilding—an approach embodied by the saying that "the ends justify the means." Violence may be necessary for the successful stabilization of power and introduction of new legal institutions. ( from Wikipedia)

Opportunistic may also convey the meaning you are describing:

• opportunistic - taking immediate advantage, often unethically, of any circumstance of possible benefit.