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Pyrrho (allegedly), c. 360 BCE (allegedly) — c. 270 BCE (allegedly)
Thinking hardly
or hardly thinking?

Icon philosophy.svg
Major trains of thought
The good, the bad,
and the brain fart
Come to think of it

Pyrrhonism is an ancient Greek philosophy of extreme skepticism. Pyrrhonists hold nothing can be known for certain and, therefore, they remain in a perpetual state of knowing nothing. Pyrrhonism is named after the Greek philosopher Pyrrho of Elis, who was one of the first advocates of extreme skepticism.[1]

Important concepts[edit]

Here are some words that had different meanings in the context of pyrrhonism than they do colloquially, or that aren’t commonly used at all.
This is an ancient Greek word usually translated as “appearance” in Pyrrhonic contexts. It basically means the perception or sensation someone has of an object or phenomonon, as opposed to its objective nature.[2] For example, someone who had red-green colour blindness looking at a leaf wouldn’t be able to tell what colour it was, while someone who didn’t could. In this case, you could say they both received different phantasias from the same thing. This applies to other senses as well, so someone with a chill and someone without one sitting in the same room could be described as having two separate phantasias of its temperature.
External object
This means what a physical thing actually is, regardless of how it’s perceived,. For example, if a tree falls in a forest and no one’s around to hear it, you might say that even though no phantasia (in this case a sound) were produced, the external object of a tree still fell and caused vibrations. A focus in Pyrrhonism was doubting whether or not anyone could know an external object with certainty.
“Aporia” is used to describe what someone believes is an unsolvable paradox in an argument.[3] The pyrrhonists worked to find them in the other philosophical systems of their time.
Criterion of truth
A criterion of truth is the rule someone uses to decide which claim is true out of several that are mutually exclusive.[4]. For example, if you need to pick between two restaurants to eat at, and they both say they’re the best in town, you need a criterion to decide who to believe. If you looked up reviews online and went to the one with the highest average rating you’d be using one, the criterion of majority rule, and if you just went with your gut you’d be using the criterion of intuition.
This is a word that’s used in its older, philosophical sense in pyrrhonism, not its meaning in the scientific method. In this context, it is an assumption to build an argument upon and comes from “hupo-“, meaning “under”, and “thesis”[5] .
Equipollence is the condition of two things that oppose each other being equally matched. For example, two cars of equal mass pushing against each other with equal force could be said to be in equipollence.[6] Abstract things can also exist in this state, and pyrrhonists specifically tried to contrast competing positions on the same issue to find ones that had equipollence.[7] They claimed that doing so forced them to suspend judgment on the thing in question. Speaking of…
“Epoché”, or “suspension of judgment” was what pyrrhonists called not deciding between two clashing assertions.[8] For example, if a complete stranger told you a movie you’d never heard of was complete trash, and another told you it was the greatest thing they’d ever seen, you might suspend judgment as to whether or not you’d like it. The pyrrhonists took this one step further, and tried to reach epoché on all philosophical questions, believing that this would lead them to…
Ataraxia was a state of calm pyrrhonists claimed to experience after reaching epoché on most or all matters.[8] The idea was basically that if you learned that no knowledge was certain you could relax and live your life without worry, since worry was supposed to be based on knowledge of what was good and bad.[9]


Information on Pyrrhonism, especially its original form, is spotty. The most comprehensive description of it comes from three books known as the Outlines of Pyrrhonism by Sextus Impericus, a later Pyrrhonist who lived sometime around the second or third century CE. How much the version of the philosophy in it matches the one held by earlier pyrrhonists is under debate.[10] According to it, however, pyrrhonists practiced their philosophy by contrasting statements about the true nature of things against each other, trying to make them reach equipollence[7]. In the process they tried to find aporias in them, thinking this brought them down to equal levels of credibility. A variety of arguments were used to do this, including two sets called the Five Modes of Agrippa and the Ten Modes of Aenesidemus. An important point is that they tried to neither accept nor deny claims, instead working towards epoché, which was more like shrugging your shoulders and deciding not to pick.[11]

The Five Modes of Agrippa[edit]

The Five Modes of Agrippa were one of two series of arguments that Pyrrhonists held proved no statement could be absolutely certain. They were basically gotchas that were supposed to apply to anything anyone asserts. Agrippa the skeptic, a philosopher who lived sometime between 50 and 150 ce, is credited as their author in the book Lives of the Philosophers[12]. Little is known about him other than this fact. While the Ten Modes challenge the accuracy of people's senses, the Five focus on the foundations of knowledge and are seen as fundamental challenges to knowledge in epistemology[12]. They’re usually given in the following order,[13] but to make their explanations a bit smoother they’ll be in a different one here.

  1. The mode based on disagreement (also known as the dissent mode)
  2. The one based on infinite regress (also known as the progress ad infinitum mode)
  3. The one based on relativity
  4. The one based on hypotheses (also known as the assumption mode)
  5. The one based on circularity

Each mode is named after the reason why certainty is impossible. Because the fourth and fifth are related to the second, they’ll be described after it, with the third argument coming last. These explanations have been condensed. The full explanations, with all specialized language and historical references, are in the book Outlines of Pyrrhonism.

The first mode was the dissent mode. It was the observation that every assertion has some people, somewhere, that disagree with it.[14] People disagree a lot, even ones who claim or are claimed to be experts, so the logic went that on any given topic you could either agree with everyone, or only some. However, if you agreed with everybody you’d have to believe mutually exclusive ideas, so you need to pick and choose who you believe. Okay, so what? The idea was that one would use a criterion of truth to choose, and the pyrrhonists suspended judgment as to whether not a criterion of proof existed.[15]

The second mode, the one based on infinite regress, is where the real meat of the philosophy starts. The logic went that for a statement to be considered true, it needs a true justification that proves it. However, any justification is a statement that itself needs proof to be credible, and so on ad infinitum.[14] It was kinda like the why-why game: the story of a kid asking their parent a question, asking “why” when they get an answer, asking “why” to the answer’s explanation, and so on.

The idea of the infinite regress has been around for a while in epistemology, the philosophy of knowledge, and has been treated in different ways by different philosophical schools throughout the millennia. The Pyrrhonists thought that it was an inescapable problem because, supposedly, there were only two ways you could avoid it, and both were flawed.[14] The first one was resorting to base assumptions, also called hypotheses (see above). The idea was that many assertations can be traced back through the chains of justifications to some statement that was just assumed to be true[16]. These assumptions are often called “justified basic beliefs” today.

The second way Pyrrhonists thought someone could assert something was through circular reasoning. Pointing this out was the fifth mode[14]. Circular reasoning is when a statement that proves something directly or indirectly relies on the thing it proves.

The last mode, the one usually numbered third, was the one based on relativity.[14] This mode basically argued that the phantasias (or appearances) people receive from any external object only exist relative to them, not on their own.[16] They claimed that, because of this, while you can say what traits something seems to have to you at the moment, you can’t assert that those traits are integral to it, nor that everyone else would register them in the same way. The Ten Modes went into this in more detail.

The Ten Modes of Aenesidemus[edit]

These ten arguments are all based of relativity and had the goal of showing that the way things seem to you isn’t necessarily what they are in reality. They usually tried to do this by showing how the same thing is perceived differently by different observers, then arguing that you can’t pick one observer’s idea to be more authentic than the others.

  1. The first mode argued that (non-human) animals can perceive things differently than humans, then that there’s no reason to hold a human’s perception as more objective than an animal’s.[17] So, for example, when a person sees a colorful painting differently than a dog does, their logic would go that there’s no reason to say that either one sees the true version of the picture, though could each follow their subjective view without holding it to be universal.
  2. The second mode argued that different people perceive the same things differently and that, because of this, while you can acknowledge the way something appears to you, you can’t expect it to appear the same to everyone else.[18] For example, if some people like the taste of mint, and some don’t, a pyrrhonist would say that neither group can claim that the flavour is objectively good or bad.
  3. The third and fourth modes tried to argue that one can’t even claim that something only appears a certain way to oneself. The third does this by pointing out how different senses can contradict each other, like how a durian is supposed to taste great but smells like a corpse. A pyrrhonist would argue that, because of this, you couldn’t technically say that the fruit itself is pleasant or disgusting, although you still could as part of normal, daily life, and instead could only truthfully say how it seemed to any given sense.[19]
  4. The fourth mode, again focusing on a single person’s perceptions, pointed out how the way one experiences something can change over time, based on all sorts of conditions.[20] For example, a joke that’s obnoxious to someone who’s grumpy might be funnier when they’re in a better mood. Food can seem to taste better when one is hungry. Because of this (or other modes like the second), a pyrrhonist who ate a shitty pre-made airline sandwich would at most figure it tasted bad to them at that time, not that it was bad in reality.
  5. This one argued that things seem different depending on their position and orientation relative to other things and their observer. A building looks smaller the farther you are from it, and things seem to have different colours depending on the hue of the light shining on them. Because of this, they would argue that while their physical features might be measured, them appearing to have them wasn’t an objective part of their nature that everyone would see.[21]
  6. The sixth mode argued that we rarely perceive things on their own, but instead usually in a combination with other objects. We hear sounds differently if they’re conducted through something solid than through the air, for example. To the pyrrhonists, this suggested that any trait an object seems to have might actually be the result of its interactions with other objects, and not inherent to it.[22] The explanation of this mode in the book Outlines of Pyrrhonism relies especially on contemporary natural philosophy to make its points, and so without adaptation might be the weakest part of the book today. In a more abstract sense, that a trait something has might only exist because of its combination with another object, this problem is what you avoid by isolating the variable you're testing in an experiment.
  7. The seventh mode points out that the same material can have different qualities depending on its state of matter (although they wouldn’t put it like that) and its amount.[23] For example, sodium is an important part of a person’s diet, but too much of it can be harmful.
  8. The eighth mode was just based on relativity in general, especially the relativity of a specific thing, for example, one tree in a park, and the abstract, general group it’s part of, like its species. It also focused on the relationship between an object and its observer.[23]
  9. The ninth mode was maybe the most particular; it argued that the rarity of a thing or event can change the qualities we see in it.[24] For example, "The sun is certainly a much more marvellous thing than a comet. But since [the ancient Greeks] see the sun all the time but the comet only infrequently, [they] marvel at the comet so much as even to suppose it a divine portent, but [they] do nothing like that for the sun."[25]
  10. The tenth mode involved comparing different cultures, customs, and other facets of society. It was mainly supposed to argue against any given norm or idea being objective fact.[23] For example, many philosophers in ancient Greece decried violence at the same time as pankratiastsWikipedia made a living beating the snot out of each other. This argument is similar to cultural relativism when it’s applied between cultures, however it’s different in that it was also supposed to be used between contradictory parts of the same society.

Pyrrhonic decision making[edit]

There’s controversy today as to how pyrrhonists were supposed to live, and how they thought they could claim to know that nothing was knowable.[10] In his writings, Sextus Impiricus, a later Pyrrhonist, described how he and his community supposedly resolved this problem. The idea was that, after acknowledging that their and anybody else’s knowledge could never be certain, they would go ahead and live their lives, acting based on what seemed apparent to them, without asserting that their beliefs were fact. They identified four sources of information they would follow to do this, since it seemed to them that they couldn’t do shit otherwise.[9] One needs to think something to do something; and most people can’t just sit there and die of thirst. These were called “criteria of action”, and were:

  1. Nature: This source of info was basically human biology, the ability to think and sense.[9] In other words, a pyrrhonist did acknowledge that they perceived the world and thought about it.
  2. Pathés: Pathé was an ancient Greek word used by pyrrhonists to roughly mean “drive”, as in, “the drive to eat”. So if a pyrrhonist felt cold they wouldn’t deny it.[9] In that case, if their senses and thoughts led them to believe that a blanket would make them warmer, they’d put one on.
  3. Laws and Customs: These were whatever they’d been led to believe by the society they lived in, the common-knowledge ideas that made participation in daily life possible.[9] Maybe Greece doesn’t exist, and Athens is trapped in a giant invisible bubble, but if one thinks that there’s no way to know for sure which is true, one might as well go with the one that won’t get in the way of a normal life.
  4. Instructions in techné, or arts and crafts: This was the knowledge needed to practice a techné, which more-or-less meant a job.[9] Again, maybe one can’t know for sure that ancient Greek engineering principles are %100 accurate, but if one is an architect one might as well follow them since doing otherwise would mean upending one's life.
Holding to the appearances, then, we live without beliefs but in accord with the regimen of daily life, since we cannot be wholly inactive.
Outlines of Pyrrhonism (page 6)

The lifestyle the pyrrhonists, at least the school that Sextus Impiricus described, tried to follow was basically to live out their lives based on information gained from the four sources above, without firmly believing anything. Their skepticism came into play when assertions about the true nature of things entered the picture, especially the nature of what they called “non-evident” things. These were things that couldn’t be observed directly and had to be inferred from other phenomena. The goal of all this was Ataraxia when it came to beliefs, and minimal anguish otherwise: the idea was if you didn’t think anything was by nature good or bad, you could only experience physical suffering like cold or pain, and not deeper kinds.[26]

Pyrrhonism and science denial[edit]

Since they lived long before the scientific method, it’s hard to say for sure how pyrrhonists would have reacted to it. The third and fourth criteria of action seem to suggest that they could have followed its conclusions, listening to the advice of accepted experts, albeit depending on its presence in the community they lived in. Regardless, one still probably wouldn’t want one as a politician or other policy-setter in the modern day, since the responsibility those positions come with call for a strong insistence on the facts — exactly the kind of firm belief they wanted to avoid.

Pyrrhonic agnosticism[edit]

Unsurprisingly, the pyrrhonists neither accepted nor denied the existence of any of the gods put forward by their contemporaries, while still participating in the normal religious rites of their communities. When it came to the various versions of God that some other schools of philosophy proposed, they argued against his existence using a variety of arguments,[27] including a version of the problem of evil:

Further, this too should be said. Anyone who asserts that god exists either says that god takes care of the things in the cosmos or that he does not, and, if he does take care, that it is either of all things or of some. Now if he takes care of everything, there would be no particular evil thing and no evil in general in the cosmos; but the Dogmatists say that everything is full of evil; therefore god shall not be said to take care of everything. On the other hand, if he takes care of only some things, why does he take care of these and not of those? For either he wishes but is not able, or he is able but does not wish, or he neither wishes nor is able. If he both wished and was able, he would have taken care of everything; but, for the reasons stated above, he does not take care of everything; therefore, it is not the case that he both wishes and is able to take care of everything. But if he wishes and is not able, he is weaker than the cause on account of which he is not able to take care of the things of which he does not take care; but it is contrary to the concept of god that he should be weaker than anything. Again, if he is able to take care of everything but does not wish to do so, he will be considered malevolent, and if be neither wishes nor is able, he is both malevolent and weak; but to say that about god is impious. Therefore, god does not take care of the things in the cosmos
Outlines of Pyrrhonism (page 110)

This is, in many more words (philosophers are great at finding loopholes, after all), saying that because God is by definition all-powerful and benevolent, you would expect evil not to exist if he did. However, according to the same people who claim he does, evil does as well. Either God is less powerful than whatever created evil, then, or he isn’t benevolent. Both possibilities go against his definition, though, so he must not be real.

As a personal philosophy[edit]

Pyrrho also believed that his philosophy could be applied to daily life, as he believed that the world's suffering is mostly caused by people's opinions and beliefs. Pyrrho advocated living in a state of epoché or perpetual indecision, as he believed that this would free people from worry and allow them to live without judging or deciding anything.[28] For Pyrrho, this included putting himself in dangerous situations because he did not believe his senses could be trusted.[10]

Any attempt to follow or live by Pyrrhonism in practice will eventually drive you batshit crazy, as it is akin to having an existential crisis 24 hours a day. (see below).

Sample 5 minutes as a Pyrrhonist[edit]

Below is a snarkilicious stream-of-consciousness transcript of how fun it is to think like a Pyrrhonist:

  1. Wake up: Did I really just wake up, or am I just imagining it? How do I know I ever slept in the first place? How do I know sleeping and being awake aren't actually the same thing?
  2. Get out of bed: How do I know this is actually a bed? How do I know I am standing? I could still be sitting or lying down for all I know. How do I know I was ever in this so-called "bed" to begin with?
  3. Look around room: How do I know this is even a room? How do I know it is mine? How do I know I am actually looking? I may not even have eyes, and how do I know that eyes are even able to perform the action that is supposedly called "looking"?
  4. Walk over into bathroom: Is this really a bathroom? There's no proof of that. How do I know I'm not still in the bedroom? How do I know that the bedroom ever existed in the first place? How do I know the bathroom even exists? How do I know I exist? How do I know that thing I may or may not have seen in that other room was the kind of object that is supposedly referred to as a "bed"?

…and so on and so forth ad infinitum…

See also[edit]


  1. Stanford Encyclopedia of Philosophy, "Ancient Skepticism"
  3. (a little ways down)
  4. Ideas of the Great Philosophers by Sahakian, William and Mabel Lewis Sahakian (1993)
  5. (definition 1.A)
  7. 7.0 7.1 Outlines of Pyrrhonism, page two
  8. 8.0 8.1 Outlines of Pyrrhonism, Page three
  9. 9.0 9.1 9.2 9.3 9.4 9.5 Outlines of Pyrrhonism, page six
  10. 10.0 10.1 10.2 Ancient Greek Skepticism
  11. Outlines of Pyrrhonism, page one
  12. 12.0 12.1
  13. Outlines of Pyrrhonism, page eight
  14. 14.0 14.1 14.2 14.3 14.4 Outlines of Pyrrhonism, page 30
  15. Outlines of Pyrrhonism, page 51
  16. 16.0 16.1 Outlines of Pyrrhonism, page 31
  17. Outlines of Pyrrhonism, page 12
  18. Outlines of Pyrrhonism, page 17
  19. Outlines of Pyrrhonism, page 18
  20. Outlines of Pyrrhonism, page 19
  21. Outlines of Pyrrhonism, page 23
  22. Outlines of Pyrrhonism, page 24
  23. 23.0 23.1 23.2 Outlines of Pyrrhonism, page 25
  24. Outlines of Pyrrhonism, page 26
  25. Outlines of Pyrrhonism (page 26)
  26. Outlines of Pyrrhonism, page seven
  27. Oulines of Pyrrhonism, page 108
  28. Stanford Encyclopedia of Philosophy, "Pyrrho"