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philosophical skepticism
The passion for philosophy...may only serve...to foster a predominant inclination...of the natural temper….There is, however one species of philosophy which seems little liable to this inconvenience, and that because it strikes ... no disorderly passion of the human mind, nor can mingle itself with any natural affection or propensity; and that is the Academic or sceptical philosophy….It is surprising, therefore, that this philosophy, which in almost every instance must be harmless and innocent, should be the subject of so much groundless reproach and blame. --David Hume, Inquiry Concerning Human Understanding
The worst speculative Sceptic ever I knew, was a much better Man than the best superstitious Devotee & Bigot. --David Hume (Letter to Gilbert Elliot of Minto, March 10, 1751)
Philosophical skepticism is a critical attitude which systematically questions the notion that absolute knowledge and certainty are possible, either in general or in particular fields. Philosophical skepticism is opposed to philosophical dogmatism, which maintains that a certain set of positive statements are authoritative, absolutely certain and true.
Philosophical skepticism should be distinguished from ordinary skepticism, where doubts are raised against certain beliefs or types of beliefs because the evidence for the particular belief or type of belief is weak or lacking. Ordinary skeptics are not credulous or gullible. They don't take things on trust, but must see the evidence before believing. Ordinary skeptics doubt the miraculous claims of religions, the claims of alien abductions, the claims of psychoanalysis, etc. But they do not necessarily doubt that certainty or knowledge is possible. Nor do they doubt these things because of systematic arguments that undermine all knowledge claims.
On the other hand, philosophical skeptics can be quite gullible. Most of what we know about ancient philosophical skepticism comes from Sextus Empiricus, who flourished around the year 200, and who believed, among other things, that some animals bypass fertilization in reproduction and originate in fire, fermented wine, mud, slime, donkeys, cabbage, fruit, and putrefied animals.
Philosophical skepticism is very ancient. For example, the sophist Gorgias (483-378 BCE) claimed that nothing exists or if something exists, it cannot be known, or if something does exist and can be known, it cannot be communicated. Gorgias, however, is known primarily as a Sophist rather than as a philosophical skeptic. Pyrrho (c. 360-c.270 BCE) is generally considered the first philosophical skeptic in western philosophy. Little is known of Pyrrho or his followers, or of the next big names in the history of skepticism, Arcesilaus (ca. 316-241 BCE) and Carneades (214-270 BCE), each of whom headed the Academy founded by Plato. The first group of philosophical skeptics are known as Pyrrhonists, the latter are known as the Academics. Neither the Pyrrhonists nor the Academics seem to have advocated the kind of nihilism Gorgias maintained.
Other sophists can also be seen as philosophical skeptics. For example, Protagoras (480-411 BCE) said that "Man is the measure of all things." This statement is usually interpreted to mean that there are no absolute standards or values and that each person is the standard of truth in all things. When applied to moral rules, this view is known as moral relativism, a type of philosophical skepticism that denies there are any absolute moral values.
Gorgias's skepticism was based upon his belief that all knowledge originates in sense experience and sense experience varies from person to person, moment to moment. His view might be called sensory Skepticism, the philosophical position that we cannot have absolute certainty about anything that is based solely on sense experience. Throughout the history of philosophy, arguments demonstrating the unreliability of sense experience have flourished, especially among dogmatists such as Plato and Descartes. One common argument is that what we perceive via the senses cannot be a reliable guide as to what is really beyond those appearances. The materialist Democritus (460-370 BCE), a contemporary of Gorgias and not generally considered a philosophical skeptic, made such an argument.
Throughout the history of philosophy, sensory skeptics have argued that we perceive only things as they appear to us and cannot know what, if anything, causes those appearances. Thus, if there is sense knowledge, it is always personal, immediate and mutable. Any inferences from appearances are subject to error and we are without a method to know whether the inferences or judgments we make are correct. However, these arguments did not prevent many skeptics from putting forth a defense of probabilism with regard to empirical knowledge. Nor has sensory skepticism hindered dogmatists from seeking absolute truth elsewhere, namely in Reason or Logic.
Perhaps the broadest criticism of the possibility of absolute truth is to be found in the skeptic's argument regarding the criterion of truth. Any criterion used to judge the truth of a claim can be challenged because a further criterion is needed by which to judge the present criterion, and so on ad infinitum. This argument did not deter philosophers such as Plato and Descartes from claiming to have found an absolutely impeccable criterion of truth. While most skeptics would reject the notion that such criteria are what their advocates claim them to be, most would probably accept the arguments of St. Augustine and others that there are absolutely certain claims, but that these are matters of Logic or definition and have nothing to do with establishing the certainty of any claim that goes beyond immediate perception.
The ancient skeptics did not all agree on even the most fundamental of matters, such as whether certainty and knowledge are possible. Some believed that they knew certainty was not possible; others claimed that they did not know whether knowledge is possible. The position that one knows that knowledge is impossible seems to be self-refuting. The view that one does not know whether knowledge is possible is consistent with the notion that it makes sense to strive to know, even if one can't be sure that one will arrive at knowledge. And, while some ancient skeptics seem to have advocated that the ideal is to have no strong opinions, most seem to have maintained that when there was a preponderance of evidence supporting the probability of one position rather than another, then belief in the more probable position was desirable. Most ancient Skeptics do not seem to have believed that simply because one cannot be absolutely certain about anything, one should therefore suspend judgment on all things. Such a view would be self-refuting. For, according to the principle itself one should not accept it, but suspend judgment on it. Suspending judgment on claims should be reserved for those claims one knows nothing about, or can know nothing about, and for those claims for which the evidence is proportionate on opposing sides. It may be true that nothing is absolutely certain, but it is not true that all claims are equally probable. A reasonable person uses probability as a guide to belief, not absolute certainty, according to most philosophical skeptics.
The Greek word skeptikoi means seekers or inquirers. Socrates, who claimed that the only thing he knew was that he knew nothing, frequently said "Skepteon," meaning we must investigate this. The Pyrrhonists sought the truth, even if most of the time that meant that they sought contrary arguments to dogmatic positions held by other philosophers, such as the Stoics or Epicureans. On those issues where argument and counterargument equaled one another, the Pyrrhonists held that we should suspend judgment. They apparently found that such a stance fit well with their desired goal of peace of mind (ataraxia). For, it is the dogmatist who gets agitated when he doesn't possess the good or truth he knows he should have, or when others refuse to accept what he knows is the truth.
The other ancient school of skeptics, the Academics, rejected their founder's metaphysical dogmatism and defended probabilism. It is this view that probabilities rather than absolute certainty are possible and do us just fine on the important matters in life that made possible the advancements of modern science in the seventeenth century. The dogmatists, led by Descartes and the Continental Rationalists, made contributions to math (analytic geometry and calculus) but not to physics; whereas, the probabilists, led by the founders of the Royal Society and the British Empiricists, made modern empirical science possible.
While probabilism in empirical matters was defended as reasonable by Skeptics, such an attitude was considered unreasonable with regard to metaphysics. One particular type of metaphysical skepticism (also known as positivism) is noteworthy: theological skepticism. A theological skeptic raises doubts regarding the possibility of knowledge about God. A theological skeptic may be an atheist, but the two positions are distinct and a theological skeptic may be a theist or an agnostic. The theological skeptic maintains that we cannot know for certain whether God exists. Such a view does not entail the notion that we should be atheists. The theological skeptic does not necessarily hold that one should only assent to absolutely certain propositions. Some theological skeptics, however, will defend atheism on the grounds that there is much more support for the probability that God does not exist than for the probability that God exists. A theist might disagree and think the probability is greater for theism. An agnostic, as distinguished from a theological skeptic, would hold that neither theism nor atheism is more probable than the other.
Theological skepticism is based upon the nature of theological claims and the nature of the human mind. Theological claims transcend the limits of human knowledge. It is for this reason that some Skeptics assert that revelation from God is necessary. Ordinary skeptics may be atheists and be completely unaware of the arguments of theological skepticism. The ordinary skeptic may be an atheist simply because he or she perceives little, if any, evidence for the belief in God.
In addition to providing philosophical doubts about metaphysics, some skeptics aimed their arguments at specific types of claims. One of the most important figures in the history of skepticism is David Hume (1711-1776), whose skeptical argument against belief in miracles is still considered by many skeptics to be the best single argument in the history of skepticism. In fact, Hume hoped his argument would serve as "an everlasting check to all kinds of superstitious delusion." Basically, Hume argues that for the same reason it is reasonable to avoid the vicious dog trying to bite us, it is reasonable to reject miraculous claims. Miraculous claims assert that a violation of the laws of nature has occurred. Laws of nature are based on experience. Experience is our guide in avoiding the vicious dog and must be our guide in judging the miraculous event. To accept an event as miraculous is to accept that experience is not a reliable guide. However, it is our only guide in such matters, unless we abandon reason and believe on pure faith. As he so eloquently and succinctly puts it:
A miracle is a violation of the laws of nature; and as a firm and unalterable experience has established these laws, the proof against a miracle, from the very nature of the fact, is as entire as any argument from experience can possibly be imagined.
What other kinds of superstitious delusions would Hume's argument apply to? It seems that it would apply to things such as homeopathy, channeling, astral projection, levitation, past life regression, psychic surgery, map dowsing, and other things which require us to abandon experience as a guide. Claims about ESP, however, would not be covered by the argument, unless advocates maintain that ESP occurs outside the realm of the laws of nature. As long as the ESP advocate claims that ESP follows natural laws but we haven't discovered them yet, then Hume's argument would not apply.
Many skeptics would agree that Logic is an area where dogmatism is justified. The principle of contradiction, that a statement is either true or false but not both, is accepted by many skeptics as true but empty. That is, such a truth reveals nothing about the world of experience. In addition to formal truths, such as the principle of contradiction or the principle of identity, most skeptics would probably accept that there are semantic truths, i.e., some statements that are true by definition. "A bachelor is an unmarried male," is true and does provide information about the world of experience, namely, how a certain word is used in a certain language. But the statement is a matter of convention, not discovery.
Philosophical skepticism was never put forth as a literal guide for practical living. The earliest Skeptics did not allow vicious dogs to bite them on the ground that their senses might be deceiving them. Even if it cannot be proved with absolute certainty that any phenomenal object is real, experience is a good guide as to the probability of what will happen if one allows a vicious dog to tear into one's leg. Skeptics don't deny the reality of sense perception. Dog bites hurt and honey tastes sweet. What the Skeptics deny is that beyond the appearances of the biting dog there is a "dog essence" or that the experience of sweetness when tasting honey justifies inferring that "sweetness" is part of the essence of honey. Skeptics don't deny appearances and subjective knowledge. They don't deny that one bitten by a dog feels real pain and knows he or she is in pain. Skeptics deny that it is justifiable to infer from subjective experience to indubitable propositions about a reality beyond those appearances. Any inference to "objective reality," a reality that transcends immediate experience, should be couched in probabilisitc language at best.
Nevertheless, ancient skepticism was considered a guide for living by its advocates. Their goal was ataraxia, a state of no perturbedness, of peace of mind. Denying appearances would not serve such a goal. Rejecting dogmatism did. Finding ways to combat dogmatism is still the central element of philosophical skepticism. Absolute certainty is not needed, according to Skeptics, either for science or for daily living. Science can do quite well even if limited to appearances and to probabilities. We can find guides for daily living, including moral principles, without needing absolute certainty. We can figure out what principles are likely to lead us to what we desire: a peaceful, happy life. Many philosophical skeptics of the Greco-Roman period advocated a very conservative lifestyle, maintaining that nature and custom know best. They advocated following the laws and customs, including the religious customs, of one's native country. They believed that following our natural appetites is a generally reliable guide to living well. It seems, however, that social and political conservatism, while probably serving well the goal of ataraxia for most skeptics, is a non sequitur. That is, such a position is not a reasonable inference from either sensory or moral skepticism. The probabilism advocated for science seems sufficient for practical living as well.
Dogmatic philosophies have become rare. The age of metaphysics is long gone, indicating that the Skeptics have won the war with the dogmatists. Logic is about the only philosophical area left where professional philosophers still speak of absolute certainty with a straight face. The chance of another Plato or Hegel arising in the 21st century seems very slim. Most philosophers today content themselves with probabilistic arguments based on empirical knowledge and the application of logical principles to concepts.
further reading
books and articles
Hume, David. An Inquiry Concerning Human Understanding, Section x "Of Miracles," (1748), Bobbs-Merrill, Library of Liberal Arts edition.
Hume, David. An Inquiry Concerning Human Understanding, Section xii "Of the Academical or Skeptical Philosophy," (1748), Bobbs-Merrill, Library of Liberal Arts edition.
Popkin, Richard H. History of Skepticism from Savonarola to Bayle (Oxford University Press, 2003).
Popkin, Richard H. "Skepticism" in The Encyclopedia of Philosophy, vol 7, pp. 449-461, ed. Paul Edwards (Macmillan, Inc., 1967).
Popkin, Richard and Avrum Stroll. Skeptical Philosophy for Everyone (Prometheus, 2001).
websites
Ancient Greek Skepticism - Internet Encyclopedia of PhilosophyAncient Skepticism - Stanford Encyclopedia
Contemporary Skepticism - Internet Encyclopedia of Philosophy
Last
updated 02/23/09
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