4.2.1 Skepticism

Blind belief in authority is the greatest enemy of truth. — Einstein

Those who can make you believe absurdities can make you commit atrocities. — Voltaire

Who shall forbid a wise skepticism, seeing that there is no practical question on which anything more than an approximate solution can be had? – Ralph Waldo Emerson

Skepticism is the philosophical position that argues we should shy away from making any “truth” claims and avoid affirming any final truths. Traditionally, Skepticism has left open the possibility that there might be an ultimate truth but suggests that claims of certainty are damaging to the philosophical enterprise, that they stagnate thinking and create a kind of closed-mindedness.

It’s important to understand that philosophy does not view the skeptical tradition negatively but argues that it has had a strong role in resisting any kind of philosophical dogmatism. “Philosophical skepticism begins with the claim that the skeptic currently does not have knowledge. Some adherents maintain that knowledge is, in theory, possible. It could be argued that Socrates held that view. He appears to have thought that if people continue to ask questions, they might eventually come to have knowledge; but that they did not have it yet.  Skeptics would argue that the field of philosophy is best served when people reserve the right to question any and all truth claims. The Greek verb skeptomai means “to look carefully upon, to reflect upon,” and the early Greek Skeptics were called the Skeptikoi because they carefully examined all such claims.

Two Forms of Skepticism.

Universal Skepticism: Universal (or Global) Skepticism claims that we can have no knowledge whatsoever. Universal Skeptics believe that every knowledge claim is unjustified and subject to doubt. Universal Skepticism, therefore, seems to require that absolutely nothing can be known (except for the knowledge that nothing can be known?).

Limited Skepticism: Limited (or Local) Skepticism denies that people do (or can) have knowledge of a particular area or subject (e.g. religion, ethics, morality). For example, a limited skeptic in Ethics believes that no one is justified in believing any claims about moral matters, perhaps because they believe that human beings cannot have any access to truths in the moral domain. A limited theological skeptic may believe that no beliefs about god can be justified, etc.

Here are some questions that may help us understand the Skeptic approach to knowledge:

• What makes our “waking experience” different from dreaming? Can you suggest some important differences between waking and dream experiences? Isn’t it possible that even our waking experience is a kind of dream or an illusion? How could you know that you are not dreaming right now that you are reading a textbook?
• What do we actually perceive when we are perceiving something? Are we perceiving something “out there” beyond our consciousness, or are we perceiving images that appear within our consciousness? Moreover, if there actually is something “out there” to perceive, how can we know that our consciousness is recording it accurately? Can we ever trust what we perceive?
• If there is something “out there,” is there any way we can ever be certain that what we are “seeing” or “experiencing” is the same as what someone else is “seeing” or “experiencing”? In fact, how can we know with certainty that there even exist minds other than our own?

A brief history of Western Skepticism

Periods of skepticism have enriched the philosophical conversation for as long as there has been philosophy. Pyrrho of Elis was perhaps the most famous skeptic of the ancient world. His thought comes to us from the later skeptic Sextus Empiricus.

Pyrrho of Elis

The main principle of Pyrrho’s thought is expressed by the word acatalepsia, which connotes the ability to suspend judgment between doctrines regarding the truth of things in their own nature as against every dogma a contradiction may be advanced with equal justification.

Pyrrhonists are not “skeptics” in the modern, common sense of the term, meaning prone to disbelief. They had the goal of αταραξια (ataraxia – peace of mind) and pitted one dogma against another to undermine belief in dogmatic propositions.

The objective was to produce in the student a state of epoché towards ideas about non-evident matters. Since no one can observe or otherwise experience things like causation, an external world (its “externality”), an ultimate purpose of the universe or life, justice, divinity, soul, etc., they declared no need to have beliefs about such things. …

Sextus Empiricus

The works of Sextus Empiricus (c. 200 CE) are the main surviving accounts of ancient Pyrrhonism. Sextus compiled and further developed the Pyrrhonists’ skeptical arguments, most of which were directed against the Stoics but included arguments against all of the schools of Hellenistic philosophy, including the Academic skeptics.

Sextus argued that claims to know or not to know were both dogmatic and as such, Pyrrhonists claimed neither. Instead, they claimed to be continuing to search for something that might be knowable.

Medieval Skepticism

Although the Middle Ages are often considered an age of faith and conformity to dogma, Charles Bolyard has argued that skepticism still influenced many philosophers of the period. Clearly, some of the greatest thinkers of this period, like St. Augustine and al-Ghazali, worked in part in response to skeptics of their time. According to Charles Bolyard:

Chronologically speaking, skeptical issues were most prominently considered in works from both the leading and tail ends of the Middle Ages. Augustine’s 4th and 5th-century attacks against the Academic Skeptics mark the beginning of such discussions, and a smattering of treatments of skeptical issues appears periodically throughout the next 800 years. From the late 13th century onwards, however, skeptical issues began to exert a dominant and wide influence on epistemological discussions, as seen in the works of such important figures as Henry of Ghent, John Duns Scotus, William of Ockham, Peter Auriol, John Buridan, and Nicholas of Autrecourt (Bolyard, “Medieval Skepticism”, The Stanford Encyclopedia of Philosophy)

Renaissance Skepticism

However, it was during the Renaissance that a great resurgence of skepticism occurred. The revival of interest in the writings and ideas of the ancient world was sweeping through Europe, suggesting that there were other ways of understanding humanity and the universe than those promoted by Christianity. The new science, typified by such figures as Copernicus and Galileo, was casting great doubt on the certainties of the Bible and Church teaching. The authority of the Church itself was being contested by the Protestant reformers. Europeans were being exposed to new ideas at a pace never experienced because of the invention of the Printing Press (the Internet of that day).

Today too many would argue we are in an age of skepticism, with the certainties of the Enlightenment and of science much in doubt. As in the renaissance, much of our skepticism comes from an excess of information. The development of the new “printing press” –the Internet—has flooded us with more information than many of us can handle leaving us to despair of truth. Some of us in frustration resign ourselves to the idea that all news is “fake news” and untrustworthy or that there is no truth, only opinions.

4.2.1.3 Descartes and Methodological Skepticism

René Descartes (1596–1650) was a French philosopher, mathematician, scientist, and lay Catholic who invented analytic geometry, linking the previously separate fields of geometry and algebra. He spent a large portion of his working life in the Dutch Republic, initially serving the Dutch Army of Maurice of Nassau, Prince of Orange, and the Stadtholder of the United Provinces. One of the most notable intellectual figures of the Dutch Golden Age, Descartes is also widely regarded as one of the founders of modern philosophy and algebraic geometry. He is largely seen as responsible for the increased attention given to epistemology in the 17th century.

Descartes’ method of doing philosophy was unique. Although Descartes himself should not be considered a Skeptic (he thought of himself as a Rationalist), he skillfully used the methods of Skepticism until he was able to arrive at some fundamental certainties that could not, he believed, be doubted. For this Methodological Skepticism, he employed what the Skeptics called universal belief falsifiers. Universal belief falsifiers are scenarios that prove that a belief could possibly be false. They are, you might say, “Yeah, but what if….” arguments. They do not prove that a belief is true or false, only that it might be false. Falsifiers need to suggest at least theoretically possible scenarios (they needn’t be probable) in which a claim to knowledge could in fact be doubted. For example, you may believe the world around you to be real, but a universal belief falsifier in response to that would be something like: “Perhaps you are simply having a very vivid dream.” The falsifier in that way provides at least one possible situation in which you are able to doubt your experience is true.

Cartesian Skepticism – Neo, Meet Rene: Crash Course Philosophy #5

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Excerpts from Descartes’ Meditations on First Philosophy

MEDITATION I. OF THE THINGS OF WHICH WE MAY DOUBT.

1. Several years have now elapsed since I first became aware that I had accepted, even from my youth, many false opinions for true, and that consequently what I afterward based on such principles was highly doubtful; and from that time, I was convinced of the necessity of undertaking once in my life to rid myself of all the opinions I had adopted, and of commencing anew the work of building from the foundation, if I desired to establish a firm and abiding superstructure in the sciences. But as this enterprise appeared to me to be one of great magnitude, I waited until I had attained an age so mature as to leave me no hope that at any stage of life more advanced I should be better able to execute my design.

On this account, I have delayed so long that I should henceforth consider I was doing wrong were I still to consume in deliberation any of the time that now remains for action. Today, then, since I have opportunely freed my mind from all cares [and am happily disturbed by no passions], and since I am in the secure possession of leisure in a peaceable retirement, I will at length apply myself earnestly and freely to the general overthrow of all my former opinions.

2. But, to this end, it will not be necessary for me to show that the whole of these are false–a point, perhaps, which I shall never reach; but as even now my reason convinces me that I ought not the less carefully to withhold belief from what is not entirely certain and indubitable, than from what is manifestly false, it will be sufficient to justify the rejection of the whole if I shall find in each some ground for doubt. Nor for this purpose will it be necessary even to deal with each belief individually, which would be truly an endless labor; but, as the removal from below of the foundation necessarily involves the downfall of the whole edifice, I will at once approach the criticism of the principles on which all my former beliefs rested.

3. All that I have, up to this moment, accepted as possessed of the highest truth and certainty, I received either from or through the senses. I observed, however, that these sometimes misled us; and it is the part of prudence not to place absolute confidence in that by which we have even once been deceived.

4. But it may be said, perhaps, that, although the senses occasionally mislead us respecting minute objects, and such as are so far removed from us as to be beyond the reach of close observation, there are yet many other of their informations (presentations), of the truth of which it is manifestly impossible to doubt; as for example, that I am in this place, seated by the fire, clothed in a winter dressing gown, that I hold in my hands this piece of paper, with other intimations of the same nature. But how could I deny that I possess these hands and this body, and withal escape being classed with persons in a state of insanity, whose brains are so disordered and clouded by dark bilious vapors as to cause them pertinaciously to assert that they are monarchs when they are in the greatest poverty; or clothed [in gold] and purple when destitute of any covering; or that their head is made of clay, their body of glass, or that they are gourds? I should certainly be not less insane than they, were I to regulate my procedure according to examples so extravagant.

5. Though this be true, I must nevertheless here consider that I am a man, and that, consequently, I am in the habit of sleeping, and representing to myself in dreams those same things, or even sometimes others less probable, which the insane think are presented to them in their waking moments. How often have I dreamt that I was in these familiar circumstances, that I was dressed, and occupied this place by the fire, when I was lying undressed in bed? At the present moment, however, I certainly look upon this paper with eyes wide awake; the head which I now move is not asleep; I extend this hand consciously and with express purpose, and I perceive it; the occurrences in sleep are not so distinct as all this. But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and, attentively considering those cases, I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished; and in amazement I almost persuade myself that I am now dreaming.

6. Let us suppose, then, that we are dreaming, and that all these particulars–namely, the opening of the eyes, the motion of the head, the forth-putting of the hands–are merely illusions; and even that we really possess neither an entire body nor hands such as we see. Nevertheless, it must be admitted at least that the objects which appear to us in sleep are, as it were, painted representations which could not have been formed unless in the likeness of realities; and, therefore, that those general objects, at all events, namely, eyes, a head, hands, and an entire body, are not simply imaginary, but really existent. For, in truth, painters themselves, even when they study to represent sirens and satyrs by forms the most fantastic and extraordinary, cannot bestow upon them natures absolutely new, but can only make a certain medley of the members of different animals; or if they chance to imagine something so novel that nothing at all similar has ever been seen before, and such as is, therefore, purely fictitious and absolutely false, it is at least certain that the colors of which this is composed are real. And on the same principle, although these general objects, viz. [a body], eyes, a head, hands, and the like, be imaginary, we are nevertheless absolutely necessitated to admit the reality at least of some other objects still more simple and universal than these, of which, just as of certain real colors, all those images of things, whether true and real, or false and fantastic, that are found in our consciousness (cogitatio), are formed.

7. To this class of objects seem to belong corporeal nature in general and its extension; the figure of extended things, their quantity or magnitude, and their number, as also the place in, and the time during, which they exist, and other things of the same sort.

8. We will not, therefore, perhaps reason illegitimately if we conclude from this that Physics, Astronomy, Medicine, and all the other sciences that have for their end the consideration of composite objects, are indeed of a doubtful character; but that Arithmetic, Geometry, and the other sciences of the same class, which regard merely the simplest and most general objects, and scarcely inquire whether or not these are really existent, contain somewhat that is certain and indubitable: for whether I am awake or dreaming, it remains true that two and three make five, and that a square has but four sides; nor does it seem possible that truths so apparent can ever fall under a suspicion of falsity [or incertitude].

9. Nevertheless, the belief that there is a God who is all powerful, and who created me, such as I am, has, for a long time, obtained steady possession of my mind. How, then, do I know that he has not arranged that there should be neither earth, nor sky, nor any extended thing, nor figure, nor magnitude, nor place, providing at the same time, however, for [the rise in me of the perceptions of all these objects, and] the persuasion that these do not exist otherwise than as I perceive them? And further, as I sometimes think that others are in error respecting matters of which they believe themselves to possess a perfect knowledge, how do I know that I am not also deceived each time I add together two and three, or number the sides of a square, or form some judgment still more simple, if more simple indeed can be imagined? But perhaps Deity has not been willing that I should be thus deceived, for he is said to be supremely good. If, however, it were repugnant to the goodness of Deity to have created me subject to constant deception, it would seem likewise to be contrary to his goodness to allow me to be occasionally deceived; and yet it is clear that this is permitted.

10. Some, indeed, might perhaps be found who would be disposed rather to deny the existence of a Being so powerful than to believe that there is nothing certain. But let us for the present refrain from opposing this opinion, and grant that all which is here said of a Deity is fabulous: nevertheless, in whatever way it be supposed that I reach the state in which I exist, whether by fate, or chance, or by an endless series of antecedents and consequents, or by any other means, it is clear (since to be deceived and to err is a certain defect) that the probability of my being so imperfect as to be the constant victim of deception, will be increased exactly in proportion as the power possessed by the cause, to which they assign my origin, is lessened. To these reasonings I have assuredly nothing to reply but am constrained at last to avow that there is nothing of all that I formerly believed to be true of which it is impossible to doubt, and that not through thoughtlessness or levity, but from cogent and maturely considered reasons; so that henceforward, if I desire to discover anything certain, I ought not the less carefully to refrain from assenting to those same opinions than to what might be shown to be manifestly false.

11. But it is not sufficient to have made these observations; care must be taken likewise to keep them in remembrance. For those old and customary opinions perpetually recur– long and familiar usage giving them the right of occupying my mind, even almost against my will, and subduing my belief; nor will I lose the habit of deferring to them and confiding in them so long as I shall consider them to be what in truth they are, viz, opinions to some extent doubtful, as I have already shown, but still highly probable, and such as it is much more reasonable to believe than deny. It is for this reason I am persuaded that I shall not be doing wrong, if, taking an opposite judgment of deliberate design, I become my own deceiver, by supposing, for a time, that all those opinions are entirely false and imaginary, until at length, having thus balanced my old by my new prejudices, my judgment shall no longer be turned aside by perverted usage from the path that may conduct to the perception of truth. For I am assured that, meanwhile, there will arise neither peril nor error from this course, and that I cannot for the present yield too much to distrust, since the end I now seek is not action but knowledge.

12. I will suppose, then, not that Deity, who is sovereignly good and the fountain of truth, but that some malignant demon, who is at once exceedingly potent and deceitful, has employed all his artifice to deceive me; I will suppose that the sky, the air, the earth, colors, figures, sounds, and all external things, are nothing better than the illusions of dreams, by means of which this being has laid snares for my credulity; I will consider myself as without hands, eyes, flesh, blood, or any of the senses, and as falsely believing that I am possessed of these; I will continue resolutely fixed in this belief, and if indeed by this means it be not in my power to arrive at the knowledge of truth, I shall at least do what is in my power, viz, [ suspend my judgment], and guard with settled purpose against giving my assent to what is false, and being imposed upon by this deceiver, whatever be his power and artifice. But this undertaking is arduous, and a certain indolence insensibly leads me back to my ordinary course of life; and just as the captive, who, perchance, was enjoying in his dreams an imaginary liberty, when he begins to suspect that it is but a vision, dreads awakening, and conspires with the agreeable illusions that the deception may be prolonged; so I, of my own accord, fall back into the train of my former beliefs, and fear to arouse myself from my slumber, lest the time of laborious wakefulness that would succeed this quiet rest, in place of bringing any light of day, should prove inadequate to dispel the darkness that will arise from the difficulties that have now been raised. (Descartes, Med. 1, in Levin, Intro to Philosophy)

Finding that the senses can be doubted and that we cannot know this is not a dream, Descartes sought to find something, some belief, that was indubitable.   Doubting all of these common-sense experiences, then, led Descartes to one of his greatest and most famous realizations.

MEDITATION II. OF THE NATURE OF THE HUMAN MIND, AND THAT IT IS MORE EASILY KNOWN THAN THE BODY.

1. The Meditation of yesterday has filled my mind with so many doubts, that it is no longer in my power to forget them. Nor do I see, meanwhile, any principle on which they can be resolved; and, just as if I had fallen all of a sudden into very deep water, I am so greatly disconcerted as to be unable either to plant my feet firmly on the bottom or sustain myself by swimming on the surface. I will, nevertheless, make an effort, and try anew the same path on which I had entered yesterday, that is, proceed by casting aside all that admits of the slightest doubt, not less than if I had discovered it to be absolutely false; and I will continue always in this track until I shall find something that is certain, or at least, if I can do nothing more, until I shall know with certainty that there is nothing certain. Archimedes, that he might transport the entire globe from the place it occupied to another, demanded only a point that was firm and immovable; so, also, I shall be entitled to entertain the highest expectations, if I am fortunate enough to discover only one thing that is certain and indubitable.

2. I suppose, accordingly, that all the things which I see are false (fictitious); I believe that none of those objects which my fallacious memory represents ever existed; I suppose that I possess no senses; I believe that body, figure, extension, motion, and place are merely fictions of my mind. What is there, then, that can be esteemed true? Perhaps this only, that there is absolutely nothing certain.

3. But how do I know that there is not something different altogether from the objects I have now enumerated, of which it is impossible to entertain the slightest doubt? Is there not a God, or some being, by whatever name I may designate him, who causes these thoughts to arise in my mind? But why suppose such a being, for it may be that I myself am capable of producing them? Am I, then, at least not something? But I before denied that I possessed senses or a body; I hesitate, however, for what follows from that? Am I so dependent on the body and the senses that without these I cannot exist? But I had the persuasion that there was absolutely nothing in the world, that there was no sky and no earth, neither minds nor bodies; was I not, therefore, at the same time, persuaded that I did not exist? Far from it; I assuredly existed, since I was persuaded. But there is I know not what being, who is possessed at once of the highest power and the deepest cunning, who is constantly employing all his ingenuity in deceiving me. Doubtless, then, I exist, since I am deceived; and, let him deceive me as he may, he can never bring it about that I am nothing, so long as I shall be conscious that I am something. So that it must, in fine, be maintained, all things being maturely and carefully considered, that this proposition (pronunciatum) I am, I exist, is necessarily true each time it is expressed by me or conceived in my mind. (Descartes, Levin, cont.)

By this method, Descartes comes to the certainty that he, the thinking self, must exist. This gives us perhaps the most famous phrase in all of philosophy: cogito ergo sum, “I think, therefore I exist.” To test this argument, simply try to doubt that you are doubting. If you claim “I am doubting” you assert there must be an “I” that is doing the doubting. Doubting/thinking cannot happen without a doubter/thinker.]

How to be a Skeptic

Skepticism does not mean simply throwing up your hands in despair and claiming that we just can’t know anything. This is a vast oversimplification of real-life Skeptical practice. In the real world, Skepticism means critically evaluating all lines of thinking regarding an idea or truth claim and testing each one for probability. It means approaching problems from the standpoint of “not knowing” in order to understand the issues more deeply.

For example, when faced with the claim that the Earth is flat, the Skeptic would first ask what arguments and proofs there are for this claim. They would then investigate all other claims regarding the shape of the planet, and the proofs backing up those opposing positions. The Skeptic’s goal is to truly understand all sides of a problem.

Skepticism has often been described as the precursor to the Scientific Method. It is not about just doubting everything and saying we can’t know anything. It is about asking critical questions and seeking justifications. The Skeptic then examines all the arguments and makes determinations with regard to which claim is more probable. Given the evidence, is it more probable to believe that the Earth is flat or round? The Skeptic understands that even though it is more probable to think that the Earth is round, it is still possible to doubt this claim.

The Skeptic holds their knowledge and opinions loosely enough that when new evidence is presented, they are capable of being open-minded and critically evaluating the new information. So, Skeptics believe lots of things, but they just hold their beliefs with an open hand instead of a closed fist.

The Strengths and Weaknesses of Skepticism

Here are some of the main strengths and weaknesses of philosophical skepticism and its extreme doubt towards certainty in knowledge:

On the one hand:

1. Skepticism questions unspoken assumptions and forces clarification and defense of alleged knowledge claims. It requires clearer thinking.  Skepticism is valuable in resisting “Group Think,” the tyranny of the majority, and a herd mentality. Skeptics are good for any community of thinkers because they often stand up to and question the certainties of the day. For example, you will recall that it was Socrates’ questioning of traditional Athenian beliefs that roused their resentment against him. In the Apology, he defended himself by saying he was sent as a “gadfly” to rouse them from their dangerous complacency and to get them to think more deeply. Skeptical anti-dogmatism has helped propel philosophy forward by forcing it to adjust to changing times.
2. It reveals logically problematic gaps, inconsistencies, and circular reasoning attempts in justifications for knowledge claims.
3. It highlights the role of subjective perspective by problematizing pretensions to neutral “God’s Eye View” objectivity.  At the same time, Skepticism challenges a kind of epistemological relativism. You’ve likely heard it said that they see the world their way while we see it ours, or they have their reality, we have ours. The Skeptic, while not taking sides, will challenge each side to prove its view of reality. Skeptics have an important role in confronting intellectual laziness. It may be that people see things from different perspectives, but the Skeptic demands to know which perspective is closer to the truth.
4. Skeptical arguments challenge human pride and presumption of knowledge, especially claims about ultimate metaphysical reality.  Skepticism is also a good precaution against hasty judgments about truth or reality.   Skepticism challenges individuals to prove their claims. Is there not a kind of danger in letting others believe things without justifying their beliefs? Wouldn’t we be helping them if, like Socrates, we got them to question their superficial certainties? There is a moral dimension to this as well. Do you not have a moral obligation, for example, to challenge a friend who believes the proposition “Hard drugs like heroin and meth won’t hurt me”?
5. Historically, skepticism has promoted intellectual humility and provided a basis for toleration, openness to rival viewpoints and moderation in claims of certainty.  Should we really be so certain about our experience and understanding of the world around us? Or should we remember the Skeptics’ caution that we remain a bit humble in our beliefs about life and the universe? Is there not a kind of danger in being too certain about “the way things are”? If we fully believe our current understanding of things to be “the truth,” will we ever question that understanding or revise those truths? If everyone believed we already have all the answers, would anyone seek better understanding?

On the other hand:

1. Skepticism can undermine any basis for action, belief, science or progress – essentially creating mental paralysis.  It sometimes can be used as an excuse not to think or inquire more deeply. How often have we heard the line “there is no right answer” used to justify giving up on trying harder to come to a conclusion? True skepticism will acknowledge perhaps that there is no absolutely right answer, but nevertheless seeks to find the best of possible answers.
2. When skeptics demand absolute standards of certainty in knowledge they may be setting the bar too high and precluding the possibility of any knowledge ever being found to be certain.
3. Skepticism fails to provide a positive alternative to ignorance.  It can even be used by some as an excuse to despair. Life without answers can be very uncomfortable for many. Philosophical skepticism should never devolve into cynicism, but instead should be used as a tool to find better answers.
4. Historically it has been equated with denial of reality and truth rather than just recognizing the limitations of our claims about them.  Skepticism too hastily precludes the possibility that there may be a right answer. Adopting radical skepticism can make one miss obvious truths when they appear. Contrariness for the sake of being contrary is not helpful to the advancement of knowledge.
5. Skepticism can be used by those in power to cast doubt upon clear evidence against them (gaslighting). One technique autocrats use is to constantly barrage us with doubts about traditional beliefs and sources. Colloquially this is known as “gaslighting,” the effort to create false narratives and make others doubt their take on things. Recall the constant refrain of “fake news” from many politicians these days, a claim used to get us to distrust information that does not come from the people in control.

So an invaluable part of philosophical examination, skepticism goes too far in immobilizing extremes. But mitigated forms that balance fallibilism against pragmatist persistence remain essential to epistemic wisdom.

Works Cited

Crash Course. “Cartesian Skepticism – Neo, Meet Rene: Crash Course Philosophy #5.” YouTube, 7 Mar. 2016, https://youtu.be/MLKrmw906TM.

“Sextus Empyricus Engraving.” Wikimedia Commons, https://commons.wikimedia.org/wiki/File:Sextus.jpg. Accessed 17 May 2022.

Stanley, Thomas. “Pyrrho, Ancient Greek Philosopher.” Wikimedia Commons, 1655, https://commons.wikimedia.org/wiki/File:Pyrrho_in_Thomas_Stanley_History_of_Philosophy.jpg. Accessed 17 May 2022.