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Title: Aenesidemus  
Author: World Heritage Encyclopedia
Language: English
Subject: Pyrrho, Agrippa the Skeptic, Hellenistic philosophy, Aenesidemus (book), Émile Saisset
Publisher: World Heritage Encyclopedia


Born 1st century BC
Era Ancient philosophy
Region Western philosophy
School Pyrrhonism
Main interests
Epistemology, Metaphysics, Ethics
Notable ideas

Aenesidemus (Photius (in his Myriobiblion) and Sextus Empiricus, and also to a lesser extent by Diogenes Laertius and Philo of Alexandria.


  • Life 1
  • Pyrrhoneia 2
    • The Ten Tropes 2.1
    • Arguments against causality 2.2
    • Physical and ethical theories 2.3
  • See also 3
  • References 4
  • External links 5


There is no definite evidence about the life of Aenesidemus, but his most important work, the Pyrrhoneia was known to be dedicated to Lucius Tubero, a friend of Cicero and member of Plato's Academy. Based on this information, scholars have assumed that Aenesidemus himself was also a member of the Academy. Furthermore, it has been assumed that he took part under the leadership of Philo of Larissa and probably developed his sceptical philosophy in reaction to Philo's fallibilism.


His chief work, known in Ancient Greek as Pyrrhôneoi logoi (Πυρρώνειοι λóγοι) and often rendered into English as the "Pyrrhonian Discourses" or "Pyrrhonian Principles", dealt primarily with man's need to suspend judgment due to our epistemological limitations. It was divided into eight books, but it has not survived. This was developed in response to the philosophical dogmatism in Plato's Academy at the time. Aenesidemus argued that his contemporaries in the Academy were unjustified in strongly affirming some theories, including ideas of the Stoics, while firmly denying others. He argued that one should "determine nothing", meaning that nothing should be either affirmed or denied. Stated more formally, Aenesidemus would never assert the statements "X is always F" or "X is never F", but rather only the statements "it is not the case that X is always F" or "it is not the case the X is never F". Given this, it seems that under his form of scepticism the only acceptable statements are negative ones. He bases this on his argument that holds that humans are incapable of knowing anything more, which is formalised in the "ten tropes".

The Ten Tropes

The reasons for epoché are given in what are often called the ten tropes or ten modes. The argument is as follows:

  1. Different animals manifest different modes of perception;
  2. Similar differences are seen among individual men;
  3. For the same man, information perceived with the senses is self-contradictory
  4. Furthermore, it varies from time to time with physical changes
  5. In addition, this data differs according to local relations
  6. Objects are known only indirectly through the medium of air, moisture, etc.
  7. These objects are in a condition of perpetual change in colour, temperature, size and motion
  8. All perceptions are relative and interact one upon another
  9. Our impressions become less critical through repetition and custom
  10. All men are brought up with different beliefs, under different laws and social conditions

In other words, he argues that truth varies infinitely under circumstances whose importance to one another cannot be accurately judged by human observers. He therefore rejects any concept of absolute knowledge, since every man has different perceptions, and he arranges this sense-gathered data in methods peculiar to himself.[1]

Arguments against causality

The second part of his work attacks the theory of causality. The proofs in his arguments bear strong resemblance to the precepts of modern skepticism. For example, he argues that cause has no inherent existence, but rather it only exists within a perceiving mind, and as such its validity can only be ideal, or subjective. To a human mind, the true relation between a cause and effect is impossible to determine. He argues that if cause and effect are different, then they must occur either simultaneously or in succession. If they happen at the same time, then in essence cause is effect and effect is cause. If they are instead in succession, then the cause must precede the effect as an effect cannot precede its cause, and therefore there must be a space of time when the cause is actually not effective, meaning that it is essentially not itself. Through such arguments he arrives at the fundamental principle of scepticism: the radical and universal opposition of causes summed up in the phrase panti logo logos antikeitai ("to every argument another argument is opposed with the same strength").[1]

Physical and ethical theories

Having reached this conclusion, he was able to assimilate the physical theory of Heraclitus, as is explained in the Hypotyposes of Sextus Empiricus. For admitting that contraries co-exist for the perceiving subject, he was able to assert the co-existence of contrary qualities in the same object. Having thus disposed of the ideas of truth and causality, he proceeds to undermine the ethical criterion, and denies that any man can aim at Good, Pleasure or Happiness as an absolute, concrete ideal. All actions are products of pleasure and pain, good and evil.[1]

See also


  1. ^ a b c   This cites:
  • Caizzi, Fernanda Decleva (1992), "Aenesidemus and the Academy", The Classical Quarterly 42 (1): 176–189,  
  • Polito, Roberto. The Sceptical Road: Aenesidemus' Appropriation of Heraclitus, Leiden: Brill, 2004.
  • Thorsrud, Harold, "Ancient Greek Skepticism", The Internet Encyclopedia of Philosophy, retrieved 23 June 2007 

External links

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