Dark Arts is a colloquial term for techniques or methods which involve deception and/or manipulation of others or oneself.
An example from the Dark Arts of Rationality:
Today, we're going to talk about Dark rationalist techniques: productivity tools which seem incoherent, mad, and downright irrational. These techniques include:
- Willful Inconsistency
- Intentional Compartmentalization
- Modifying Terminal Goals