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Related to necessary: Necessary and sufficient
Something bad that must exist or occur in order for something good to happen. These days, student loans are a necessary evil in order to get an education that leads to a well-paying job. Some view dictators as a necessary evil who keep the region stable by suppressing more radical elements.
deem it necessary
To determine that something is necessary. I didn't deem it necessary to give the boys detention because having their shirts untucked isn't a very serious infraction.
deem it (to be) necessaryand deem that it is necessary
to decide that something is necessary. Mary deemed that it was necessary to leave town that night. Lisa deemed it necessary to go home.
If God did not exist, it would be necessary to invent Him.
Prov. People need a deity to worship. (This is an English translation of a quote from Voltaire. It is often parodied, using a person's name instead of God and implying that the person is somehow necessary.) The atheist tried to convince Jerry that God does not exist, and that people should not waste their time worshiping Him. "But you can't stop people from worshiping God," Jerry replied. "If God did not exist, it would be necessary to invent Him." The unscrupulous mayor was such a convenient scapegoat for the city's problems that if she had not existed, it would have been necessary to invent her.
a necessary evil
COMMON If you describe something as a necessary evil, you mean that although it is unpleasant, it is needed. He viewed war as a necessary evil. Managers sometimes think that training is a necessary evil that has to be done but is too expensive.
a necessary evilsomething that is undesirable but must be accepted.
1997 Internet World Advertising may be a necessary evil. After all, someone has to support Internet ventures.
a ˌnecessary ˈevila thing that is unpleasant or even harmful, but which must be accepted because it brings some benefit: Injections against tropical illnesses are a necessary evil when you are planning to travel to that part of the world. ♢ I suppose all these security measures are a necessary evil.
n. money; an income. (Also a really old term for a toilet or bathroom.) I can always use more of the necessary.