The answer to the question in the title might seem obvious, but I think it’s more complicated than most people might think.

Let’s leave out accusers who are telling the truth. I’m interested in the ones who are not. They can have multiple motives; any of these can be combined. This list is not all-inclusive, but here are the major ones:

(1) Revenge. The person actually has hurt you in some way—estranged spouses are notorious for this motivation—but you’re making up a story with an accusation that can hurt them even more than the truth would, and you justify it by telling yourself they deserve it.

(2) Attempting to deflect your own guilt onto an innocent person when you are guilty of something and might yourself be accused.

(3) You’re a sociopath who enjoys lying and gets off on seeing people squirm. Makes you feel superior to all those stupid normals.

(4) Someone has paid you money to lie.

(5) You want your 15 minutes (or more) of fame.

(6) An actual psychological contagion effect, a kind of mass hysteria in which people start thinking they remember something that is really just a reflection of what they’re hearing from others. Obviously, for this motive to be operating there must be other accusers and a lot of attention given to them, which is often true for a public figure. I believe that this was at least part of the motive for the girls doing the accusing in the Salem witch trials, for example. Do not underestimate the power of the strangeness of the human mind.

(7) (This one is related to #5, but somewhat different.) Some time ago, something happened to you that was bad, but your memory is foggy on some details. When you really think about it (or are coaxed to do so, perhaps by a therapist or reporter or attorney), you become convinced that it happened a certain way at a certain person’s hands. And yet this is actually a manufactured memory detail superimposed on a much hazier basic memory that is real. People who are undergoing numbers 6 or 7 can make very convincing witnesses indeed, because they have convinced themselves of the absolute truth of their memories and can therefore speak with the power of tremendous conviction.

(8) You believe this is a noble lie you are telling because the cause is noble. This is the mentality of some spies, or people working for the real Resistance during a war, in which that person can easily justify lying, making false documents, perhaps even assassination, for the sake of the greater good. Right now, for example, if a person believes, truly truly believes, that the right is waging a War on Women, let’s say, and that women’s very liberty is at stake if the evil Kavanaugh gets on the Court, that person could easily justify lying in order to take him down.

(9) You once had something similar happen to you at the hands of someone else, and that person shares a lot of traits with the person being accused. That person who did something very upsetting to you never apologized or looked back, and may have even gone on to great glory and fame and achievement in life. You want justice and never got it. For some people in that circumstance, it becomes easy to tell themselves that there’s nothing wrong with telling a little white lie to expose what a scumbag that new person must be.

[Neo is a writer with degrees in law and family therapy, who blogs at the new neo.]