Prohairesis is a fundamental concept in the Stoic

Stoicism

Stoicism is a school of Hellenistic philosophy founded in Athens by Zeno of Citium in the early . The Stoics taught that destructive emotions resulted from errors in judgment, and that a sage, or person of "moral and intellectual perfection," would not suffer such emotions.Stoics were concerned...

 philosophy of Epictetus

Epictetus

Epictetus was a Greek sage and Stoic philosopher. He was born a slave at Hierapolis, Phrygia , and lived in Rome until banishment when he went to Nicopolis in northwestern Greece where he lived the rest of his life. His teachings were noted down and published by his pupil Arrian in his Discourses...

. It represents the choice involved in giving or withholding assent to impressions. The use of this Greek word was first introduced into philosophy by Aristotle

Aristotle

Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

 in the Nicomachean Ethics

Nicomachean Ethics

The Nicomachean Ethics is the name normally given to Aristotle's best known work on ethics. The English version of the title derives from Greek Ἠθικὰ Νικομάχεια, transliterated Ethika Nikomacheia, which is sometimes also given in the genitive form as Ἠθικῶν Νικομαχείων, Ethikōn Nikomacheiōn...

. To Epictetus it is the faculty that distinguishes human beings from all other creatures. The concept of ‘Prohairesis’ plays a cardinal role in the Discourses

Discourses of Epictetus

The Discourses of Epictetus are a series of extracts of the teachings of the Stoic philosopher Epictetus written down by Arrian c. 108 AD. There were originally eight books, but only four now remain in their entirety, along with a few fragments of the others...

and in the Manual

Enchiridion of Epictetus

The Enchiridion, or Handbook of Epictetus, , often shortened to simply "The Handbook", is a short manual of Stoic ethical advice compiled by Arrian, who had been a pupil of Epictetus at the beginning of the 2nd century....

: the terms ‘Prohairesis’, ‘Prohairetic’ and ‘Aprohairetic’ appear some 168 times.

Explanation by Epictetus

According to Epictetus, nothing is properly considered either good, or bad, aside from those things that are within our own power to control, and the only thing fully in our power to control is our own volition (prohairesis) which exercises the faculty of choice that we use to judge our impressions. For example, if a person says something critical to us, that is not bad; or, if something complimentary is said, that is not good, because such things are externals and not in our power to control. By exerting the power of choice, it is possible to maintain equanimity in the face of either criticism and praise, which is a moral good. On the other hand, when people become troubled by criticism, or elated by praise, that is a moral evil because they have misjudged impressions by thinking that things not in their power (such as criticism or praise) have value, and by doing that they place a measure of control of their own life in the hands of others.

The importance of prohairesis for Epictetus is that it exerts a power that allows people to choose how they will react to impressions rationally:

Remember that what is insulting is not the person who abuses or hits you, but the judgment that these things are insulting. So when someone irritates you, realize that it is your own opinion that has irritated you. Try, therefore, in the first place, not to be carried away by the impression; for if you once gain time and respite, you will find it easier to control yourself.

By exerting their prohairesis (will, volition, or choice), people can choose rationally how to react to impressions. Prohairesis is the faculty that distinguishes human beings from all other creatures. Epictetus defines it as:

1. a rational faculty able to use the impressions and to which all other human faculties are subordinated (e.g.: Discourses II.23.6-15; II.23.20-29)
2. a faculty capable of using impressions and understanding their use (e.g.: Discourses II.8.4-8)
3. a self-theoretical faculty able to evaluate all other human faculties (e.g.: Discourses I.1.1-13; I.17.1-3; I.20.1-6)
4. a faculty impossible to be enslaved (e.g.: Discourses II.10.1; I.17.21) and impossible to subordinate (e.g.: Discourses II.10.1; I.17.21; IV.1.161)