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In Hellenistic philosophy the term "phantasia" is information based on sense experience.

Plato described phantasia as a blend of perception and doxa (judgement/opinion).[1]

Aristotle placed phantasia between perception and thought. For Aristotle phantasia is based on sense perception[2] and includes mental images, dreams, and hallucinations.[3]

The Pyrrhonists, Epicureans, and the Stoics use the term to refer to information received through the senses. In translations of Pyrrhonist texts the term is usually rendered as "appearances" but in translations of Stoic texts there is no consensus how to translate the term, with "appearance," "impression," "presentation," and "representation" all in use.[4]

In Stoicism the phantasiai represent pre-cognitive judgments originating from our previous experiences or our subconscious thinking. For example: cats are nice, or cats are selfish; the square root of 9 is 3, or the square root of 9 is 4. The phantasiai are contrasted with what the Stoics call "assent" (sunkatathesis), which is the confirmation, usually at a cognitive level, of the initial impression: cats are indeed selfish animals; the square root of 9 is indeed 3. (Obviously, one can deny assent to other impressions, like that cats are actually nice, or that the square root of 9 is 4.)[5]

Pyrrhonists maintain that phantasia cannot be relied upon to represent reality. Phantasia just appear to be real. The Stoics, however, hold a doctrine called katalepsis, which claims that phantasia can be self-evidently certain. Katalepsis is traditionally explained based on a metaphor of how an image can be impressed upon wax, such that the image in wax corresponds with the design of the impression. For the Stoics, katalepsis represents the criterion of truth and a secure basis for knowledge, thus solving the problem of the criterion. Katalepsis was denied by the Pyrrhonists and the Academic Skeptics.


  1. ^ Sophist 264a
  2. ^ De anima 3.9
  3. ^ De anima 3.3
  4. ^ Aldo Dinucci, "Phantasia, Phainomenon and Dogma in Epictetus", Athens Journal of Humanities & Arts - Volume 4, Issue 2 – Page 102
  5. ^