Fear of Infinity

It normally begins in adolescence or earlier, and how it develops afterwards is not known.

What the thought hooks onto

The suggested cause is existential dread about eternal life or about oblivion after death, which puts it in company:

• thanatophobia, for death
• chronophobia, for time and its passing
• nihilophobia, for nothingness Sufferers commonly report derealization, in which reality is perceived as dreamlike or distorted, which is an unusual symptom for a specific phobia and a common one for the conditions this sits beside.

Existential obsessive-compulsive disorder is named as one route in. Obsessive thoughts about infinity or eternity can lead to the phobia or trigger it, and like other phobias this one may be tied to anxiety disorders or to obsessive-compulsive disorder generally.

What is known about apeirophobia

There is very little research on it. The American Psychiatric Association does not recognise it specifically in the DSM-5, though it meets the manual's own criteria for a specific phobia, which is a type of anxiety disorder. No treatment has been designed for it. Some sufferers have benefited from anti-anxiety medication or cognitive behavioural therapy, which is what is available rather than what was intended.

Why the word belongs to philosophy

Apeirophobia's recorded uses are mostly academic and mostly about other people's arguments. Reinhardt Grossman, writing on the theory of knowledge in 1990, says his own view is free from apeirophobia, the horror of the infinite, which coloured so much of what was written at the beginning of the twentieth century about the foundations of mathematics. Christopher Smith, in 1998, writes that the clearest evidence of Aristotle's apeirophobia is in the Posterior Analytics, book one, chapters nineteen to twenty-two.

Both are using the word as a charge in an argument rather than as a description of anybody's distress, and the target in each case is a philosopher's refusal to admit an infinite series. That usage is older in print than the clinical one and it is the reason the word exists at all.

A third use, from a study of infinity on the stage published in 1999, puts apeirophobia next to the fear of death and the fear of corpses and suggests it prods them into being, which is the same reading Martin Wiener arrived at from neuroscience.

Where the reports actually come from

Bobby Azarian, writing in The Atlantic in September 2016 under the title Apeirophobia: The Fear of Eternity, is careful about what he has. Wiener's explanation would predict that the fear appears at younger stages of life, and, in Azarian's words, although nothing can be known for certain without sufficient data, the reports scattered across the web seem roughly to match that. He adds that a small proportion, himself included, first felt it before adolescence.

That sentence is the honest state of the evidence for this term. There is a hypothesis, there is a pattern in self-reports collected informally online, and there is an explicit acknowledgement that the data to test it does not exist.