Existential Angst is one of the three corners of the Existential Triangle along with the People as Scenery theory and the Anthropic Fallacy. People suffering from Existential Angst are either not convinced that they exist, unsure why they exist or not at all convinced that anything really exists at all. The Cartesian summary of this hypothesis (or really a lack of any clear hypothesism) is "I (if there is an I) might think, therefore I (ditto) might (if anyone actually cares) be". Some take is as far as "There's no point in even thinking as I might not be anyway". Most French employers allow paid leave to be taken for these reasons.