In a general sense, skepticism or scepticism (Greek: skeptomai, to look about, to consider) refers to any doctrine or way of thought denying the ability of our mind to reach certainty.
Originating in the human tendency to question the reliability of any statement before accepting it, skepticism has taken on a variety of forms throughout the ages. It can refer both to an attitude in ordinary life and to philosophical positions. Skepticism is often contrasted with dogmatism, the position that certain truth can be reached by the application of an appropriate method. Epistemology, the inquiry into the conditions for certainty in knowing, has led practically every thinker to adopt, at least temporarily, some form of limited skepticism in one regard or another. And some of the greatest philosophers, such as David Hume, have come to the conclusion that certain knowledge is essentially unattainable. By its very nature, skepticism is unsatisfactory as an end result. Whether it is ultimately embraced or rejected thus depends in great part on one’s general outlook of life, pessimism being generally associated with the skeptical option. In any case, however, skepticism has played an irreplaceable role as a catalyst in the history of philosophy.
In ordinary usage, skepticism or scepticism refers to (1) an attitude of doubt or a disposition to incredulity either in general or toward a particular object, (2) the doctrine that true knowledge or knowledge in a particular area is uncertain, or (3) the method of suspended judgment, systematic doubt, or criticism that is characteristic of skeptics (Merriam–Webster).
The word skepticism can characterize a position on a single claim, but in scholastic circles more frequently describes a lasting mindset and an approach to accepting or rejecting new information. Individuals who proclaim to have a skeptical outlook are frequently called "skeptics," often without regard to whether it is philosophical skepticism or empirical skepticism that they profess.
In philosophy, skepticism refers more specifically to any one of several propositions. These include propositions about (1) the limitations of knowledge, (2) a method of obtaining knowledge through systematic doubt and continual testing, (3) the arbitrariness, relativity, or subjectivity of moral values, (4) a method of intellectual caution and suspended judgment, (5) a lack of confidence in positive motives for human conduct or positive outcomes for human enterprises, that is, cynicism and pessimism (Keeton, 1962).
One well-known drawback of the skeptical position is that it easily leads to statements of the type “reaching truth is impossible,” which itself amounts to a claim to truthful knowledge. Skeptic philosophers have attempted to avoid this trap, but they have usually been less than fully successful due to the inevitably paradoxical nature of their claim. On the other hand, the difficulties associated with the mediate nature of our rational and experimental knowledge have represented a permanent invitation to try the skeptical option. As a result, all forms of philosophy, ancient and modern, tend to present at least some elements of skepticism and at the same time some elements of dogmatism. A deliberately skeptical approach has also been employed as a tool to test the certainty of fundamental statements about reality, as with the Cartesian doubt. In such a case, the final aim is certainty and not skepticism, whether the solution is satisfactory or not.
Pessimism is naturally associated with skepticism to the extent that our desire to know is perceived to be irremediably frustrated. Additionally, epistemological skepticism invariably leads to uncertainty on the level of ethical action, thus further leading to a pessimistic outlook.
But the skeptical outlook is not necessarily linked to a pessimistic attitude. Ancient Greek skeptics associated skepticism to the suspension of judgment (epoche), or the refusal to make dogmatic claims. This, they felt, lead to Ataraxia Αταραξία), a Greek term used by Pyrrho and Epicurus for tranquility, freedom from disturbance of judgment, the first step to achieve Hêdonê, or pleasure.
Agnosticism is typical of mild forms of skepticism, such as that of Immanuel Kant’s critical philosophy. To Kant, even the moderate skepticism of David Hume was unacceptable, but the certainties of his own system never reached beyond the level of phenomena and the belief of practical reason, hence it has been characterized as epistemological agnosticism.
Empiricism is often linked to skepticism, because the direct testimony of experience, though subjected to the uncertainties of evaluation and interpretation, still offers tentative responses that are immediately available. Rational deduction, on the other hand, implies a confidence in the mind’s ability to reach certainty. If that confidence is lost, nothing remains. Thus, the skeptically oriented mind will tend to cautiously use empirical data and refute all the claims of rationalism.
Pragmatism is another common feature of skeptical philosophy that is related to empiricism. In the absence of theoretical certainties, action based on what brings immediately verifiable satisfactory results may appear to be the best option. In the absence of a clear and reliable framework of measurement, it is, however, always possible that an apparently beneficial contribution may prove to be detrimental in the end. In this, pragmatism meets its limit.
Relativism is not a necessary consequence of skepticism, but is has often been applied as a response to the challenge raised by the skeptical position. If truth is a matter of perspective, the need to justify absolute statements disappears.
The issue of intersubjectivity represents a major challenge related to skepticism. How is it possible for me to ascertain that my perception of a red item corresponds in any way to another person’s perception of that same item, though we may, for convenience, use the same term ‘red’? In other words, how is it possible in any way to go beyond one’s own immediate perceptions and establish universally valid criteria of measurement?
In classical philosophy, skepticism refers to the teachings and the traits of the Skeptikoi, a school of philosophers of whom it was said that they "asserted nothing but only opined" (Liddell and Scott). In this sense, philosophical skepticism, or pyrrhonism, is the philosophical position that one should avoid the postulation of final truths. The common source of skepticism in the history of philosophy can be described as the mind’s astonishment when confronted with several, apparently equally valid but contradictory views. The inability to reconcile them satisfactorily leads to the adoption of a skeptical position.
In religion, skepticism refers to "doubt concerning basic religious principles (as immortality, providence, and revelation)" (Merriam–Webster).
Philosophical skepticism, at least in its western form, originated in ancient Greek philosophy. For Heraclitus, all things were in a permanent state of flux (his dialectic), hence the static notion of an absolute truth was illusory. His opponent, Parmenides, on the other hand, claimed that change was illusory and unchanging being alone was real. Hence, his position was skeptical in regard to the meaning of observable phenomena. Along a similar line, the school of the Sophists emphasized the sort of skeptical relativism that gave them a bad name, that of justifying anything with clever arguments. The views of their main proponents, Gorgias and Protagoras were sharply criticized by Socrates.
However, ancient skepticism is primarily associated with the name of Pyrrho of Elis (c. 360-275 B.C.E.), who advocated the adoption of 'practical' skepticism. Pyrrho (c. 360-c. 270 B.C.E.) is usually credited as being the first skeptic philosopher and is the founder of the school known as Pyrrhonism. Little is known of his actual thought and we only know his biography through indirect sources. Much of it is of doubtful historical authenticity. Diogenes Laertius, quoting from Apollodorus, says that he was at first a painter, and that pictures by him were in existence in the gymnasium at Elis. Later he was diverted to philosophy by the works of Democritus, and became acquainted with the Megarian dialectic through Bryson, pupil of Stilpo.
Pyrrho, along with Anaxarchus, is said to have traveled with Alexander the Great on his exploration of the east, and studied in India under the Gymnosophists and under the Magi in Persia. From the Oriental philosophy he seems to have adopted a life of solitude. Returning to Elis, he lived in poor circumstances, but was highly honored by the Elians and also by the Athenians, who gave him the rights of citizenship. His doctrines are known mainly through the satiric writings of his pupil Timon of Phlius (the Sillographer).
The main principle of his thought is expressed in the word "acatalepsia," which implies the impossibility of knowing things in their own nature. Against every statement the contradictory may be advanced with equal reason. Secondly, it is necessary in view of this fact to preserve an attitude of intellectual suspense, or, as Timon expressed it, no assertion can be known to be better than another. Thirdly, these results are applied to life in general. Pyrrho concludes that, since nothing can be known, the only proper attitude is "ataraxia" ("freedom from worry").
The impossibility of knowledge, even in regard to our own ignorance or doubt, should induce the wise man to withdraw into himself, avoiding the stress and emotion which belong to the contest of vain imaginings. This drastic skepticism is the first and the most thorough exposition of agnosticism in the history of thought. Its ethical results may be compared with the ideal tranquility of the Stoics and the Epicureans.
The proper course of the sage, said Pyrrho, is to ask himself three questions. Firstly we must ask what things are and how they are constituted. Secondly, we ask how we are related to these things. Thirdly, we ask what ought to be our attitude towards them. As to what things are, we can only answer that we know nothing. We only know how things appear to us, but of their inner substance we are ignorant.
The same thing appears differently to different people, and therefore it is impossible to know which opinion is right. The diversity of opinion among the wise, as well as among the vulgar, proves this. To every assertion the contradictory assertion can be opposed with equally good grounds, and whatever my opinion, the contrary opinion is believed by somebody else who is quite as clever and competent to judge as I am. Opinion we may have, but certainty and knowledge are impossible. Hence our attitude to things (the third question) ought to be complete suspension of judgment. We can be certain of nothing, not even of the most trivial assertions.
Plato’s philosophy, with its belief in absolute truth in the world of eternal ideas, seems to be an unlikely source of skepticism. However, one should remember that Plato’s master, Socrates, stated that he only knew that he knew nothing, and that this was his sole claim to wisdom. Also, his method, the Socratic dialectic, consisted of showing his interlocutors that what they held to be secure knowledge was a mixture of contradictory ideas. A good example is the so-called Euthyphro dilemma (from a question asked by Socrates in the dialogue Euthyphro): “Are morally good acts willed by the gods because they are morally good, or are they morally good because they are willed by the gods?”
The final aim of the Socratic Method and of the Platonic philosophy, however, is not to promote doubt, as was the case for the Sophists whom Socrates opposed, but rather to show the unreliable nature of mere opinion and sensual knowledge. In the case of the Euthyphro dilemma, the obvious aim is to eliminate a prevalent, superficial and contradictory view of the gods and their role in human affairs. In that sense, it is skeptic. But the purpose of the doubt thus created in the mind is to redirect the attention to one’s conscience. It is to reach higher truth in the realm of ideas, or rather to rediscover one’s pre-existing knowledge of it.
Nevertheless, as this particular example shows, the Socratic discursive method can lead to some permanently unsettled questions. It is thus not entirely surprising that some of Plato’s disciples, by emphasizing this aspect, created what came to be known as Academic Skepticism. In the “New Academy,” Plato’s successors Arcesilaos (c. 315-241 B.C.E.) and Carneades (c. 213-129 B.C.E.) developed theoretical perspectives, by which conceptions of absolute truth and falsity were refuted. Diogenes Laertius criticized Aecesilaos for “meddling” with Plato’s thought, while Cicero, who remains one of the main sources on this form of skepticism, praised him for “reviving” Plato’s thought. This controversy can be said to prefigure, in some sense, Jacques Derrida’s twentieth century deconstructionist reading of Plato (“Plato’s pharmacy”).
Carneades criticized the views of the Dogmatists, especially supporters of Stoicism, asserting that absolute certainty of knowledge is impossible. Sextus Empiricus (c. 200 C.E.), the main authority for Greek skepticism, developed the position further, incorporating aspects of empiricism into the basis for asserting knowledge. His views would have a considerable influence on modern thinkers like Michel de Montaigne and David Hume.
Greek skeptics were particularly critical of the Stoics for their metaphysical claims and for their dogmatic assertions in fields like ethics and epistemology. For the skeptics, the logical mode of argument was untenable, as it relied on propositions which could not be said to be either true or false without relying on further propositions, leading to infinite regress. In addition, the skeptics argued that two propositions could not rely on each other, as this would create a circular argument (as p implies q and q implies p). For the skeptics, such logic was thus an inadequate measure of truth that could create as many problems as it claimed to have solved. Truth was not, however, necessarily unobtainable, but rather an idea which did not yet exist in a pure form. Although skepticism was accused of denying the possibility of truth, in actual fact it appears to have mainly been a critical school that merely claimed that logicians had not discovered truth.
The Middle Ages are a period known more for its assertion of faith than for its skepticism. The “negative” approach to theology, generally linked to medieval mysticism, consisted of describing God by what he is not rather than by what he is. The implication of this position is that God, the infinite Being, is beyond any words that could be used to describe him. In spite of its negative form, it thus affirms God unambiguously. But, by the way it chooses, it also expresses considerable skepticism towards the capacity of human reason to grasp what is essential. An example of this approach is Nicholas of Cusa’s De Docta Ignorantia (“Of Learned Ignorance”). Similar tendencies can be found in Muslim philosopher and Sufi mystic Al-Ghazali and Jewish philosophers Maimonides and Judah ha-Levi among others.
The clash between dogmatism and skepticism in the Middle Ages thus mainly involved the confrontation between the rational claims of Aristotelian philosophy and the response of monotheistic fideism. This debate would give its shape to the great theological systems to emerge during that period.
With the advent of modernity, the field became open once again for a much wider application of the skeptical viewpoint, including the many instances when it was aimed at religious knowledge. Some thinkers, however, would persist in a skeptical appraisal of the power of reason in order to make place for faith. Elements of this approach can be found in thinkers as diverse as Blaise Pascal and George Berkeley. Sometimes, this approach would result in the opposite of what was intended, namely full skepticism (e.g., Berkeley’s influence on David Hume).
In the sixteenth century, French philosophical writer Michel de Montaigne expressed general doubt about the power of our human faculties, which led him to an attitude of common sense acceptance of life’s situations not altogether different from what would be the skeptical pragmatism of Hume.
Generally speaking, epistemological skepticism in the seventeenth century was aimed at the innate power of reason (empiricists) or at the reliability of our senses (rationalism). Both sides, however, rejected full skepticism in their initial phase, merely rejecting the opposite approach as a reliable source of certainty. Through his methodic doubt, René Descartes attempted to reach sure knowledge by starting from inner certainty. On the contrary, John Locke essentially believed that sense perception (experience), rather than innate ideas, was a genuine source of knowledge. Common sense served as a bulwark against skepticism. In a later stage, however, both schools had the consistency of their approach challenged, which led to skeptical developments. Most famously, David Hume challenged Locke, leading British Empiricism to full-fledged skepticism. Even Hume, however, rejected the Pyrrhonian form of skepticism and kept his theoretical considerations firmly anchored in common sense pragmatism.
On the continent, Pierre Bayle, published a Dictionnaire historique et critique (1697-1702) in which contemporary systems were demolished and presented as illusory. Bayle was followed by the eighteenth century Enlightenment, which further challenged continental rationalism.
The French Enlightenment in many ways developed a view that was closer to the pragmatism of Locke and Hume than to the rational dogmatism that had immediately preceded them. With figures like Voltaire, this attitude of wholesale skepticism towards absolute claims, be they religious or philosophical, involved a good dose of cynicism as well. This form of skepticism implied a distrust of human sincerity and good will. It would also be aimed at the value of existing social institutions, as with Jean-Jacques Rousseau.
The age of the Enlightenment came to an end with the philosophical synthesis of Immanuel Kant, who believed he had overcome Hume’s skepticism while avoiding the false claims of dogmatism. His own thought, however, can legitimately be called a form of agnosticism, since he did not believe that knowledge of things in themselves was possible. His critical philosophy would have far reaching consequences both in the theory of knowledge and in ethics and the philosophy of religion. The limited certainty available to us in the world of phenomena was further attacked as illusory by Kant’s various successors, with the notable exception of the German Idealists at the beginning of the nineteenth century. And Kant’s ethical and religious views set the tone for a denial of the objective validity of particular religious claims in the following generations.
Any positive assertion rests on the availability of firm criteria. It is thus not surprising that moral values and, more generally, anything that cannot be reduced to empirical verification, came to be looked upon with great skepticism by thinkers of the modern area dominated by the scientific view of things. Certainty in the realm of ethics had primarily relied on Aristotle’s philosophy and on Christian dogma – both of which gradually lost their unchallenged authority. It increasingly became the trademark of modern thought to consider the question of values a matter of opinion, in contrast to scientific data that are seen as a matter of fact. In the multicultural contemporary world, this dichotomy between religious and ethical views and scientific knowledge has never found a satisfactory answer receiving a large degree of acceptance.
In twentieth century philosophy, few if any systems appeared that claim to know objective reality “as it is” in any traditional way. Though the thinkers who emerged during that period do not generally label themselves primarily as skeptics, skepticism remains a pervasive feature of their work. Marxism and its various offshoots has perhaps been the only recent system of major importance to make unmitigated dogmatic claims about its theoretical and practical ability to control reality.
Existentialism, based on the nineteenth-century philosophy of Søren Kierkegaard, showed an overall skepticism not only towards the validity of rational inquiry, but also towards its human meaningfulness, thus shifting its own focus away from epistemology. Logical positivism, analytic philosophy and linguistic philosophy, the heirs to British Empiricism, as well as the various schools of European continental philosophy, culminating in deconstructivism, are all opposed to so-called foundationalism, i.e., the view that it is possible to find a secure, ultimate foundation to our knowledge.
The view that the quest for “truth” is only legitimate when it limits itself to the analysis of the content of logical or verbal propositions is found in the thought of thinkers such as Bertrand Russell, A. J. Ayer and Rudolf Carnap. The philosophy of Ludwig Wittgenstein (Tractatus Logico-Philosophicus) also bears some “family resemblance” with this current of thought. Philosopher of science Karl Popper substituted the notion of falsifiability to that of verifiability. It is never possible to verify the universal validity of a statement through induction, since there is always the possibility that one example contradicting that statement will come up at some point, thus falsifying it. The lesser claim that a statement makes sense if it is falsifiable should thus be substituted. Statements that are not potentially falsifiable are nonsensical. This again raises the question of the range of statements that can be considered falsifiable by being the objects of valid criteria. For instance, are statements of a spiritual nature falsifiable?
Finally, the view that “truth” can be the object of various interpretations of equal legitimacy and that choices of interpretations are often made based on social and political bias is typical of philosophers like Jacques Derrida and Michel Foucault.
Skepticism as it has developed in the western philosophical tradition has numerous counterparts in other traditions. Often, these approaches are more experiential and less strictly theoretical. The notion of the Veil of the Maya found in Hinduism and Buddhism and reflected in the thought of Arthur Schopenhauer implies that our natural approach to knowledge is illusory and leads us away from our actual goal.
The belief that it is vein to search for answers in the straightforward way of the common man and that true knowledge comes unexpectedly through enlightenment reaches its apex in Zen Buddhism. This approach is not entirely unlike that of some of the Ancient Greek skeptics, particularly Sextus Empiricus.
An empirical skeptic is one who refuses to accept certain kinds of claims without subjecting them to a systematic investigation. For many empirical skeptics, this process is akin to the scientific method. This does not mean that the empirical skeptic is necessarily a scientist who conducts live experiments (though this may be the case), but that the skeptic generally accepts claims that are in his/her view likely to be true based on testable hypotheses and critical thinking.
Most empirical skeptics do not profess philosophical skepticism. Whereas a philosophical skeptic may deny the very existence of knowledge, an empirical skeptic merely seeks likely proof before accepting that knowledge.
Scientific skepticism is a branch of empirical skepticism that addresses scientific claims. Common topics in scientifically skeptical literature include health claims surrounding certain foods, procedures, and medicines, such as homeopathy, Reiki, Thought Field Therapy (TFT), vertebral subluxations; the plausibility of supernatural entities (such as ghosts, poltergeists, angels, and gods); as well as the existence of ESP/telekinesis, psychic powers, and telepathy; topics in cryptozoology, Bigfoot, the Loch Ness monster, UFOs, crop circles, astrology, repressed memories, creationism, dowsing, conspiracy theories, and other claims the skeptic sees as unlikely to be true on scientific grounds.
Religious skepticism is skepticism regarding faith-based claims. Religious skeptics may focus on the core tenets of religions, such as the existence of divine beings, or reports of earthly miracles. A religious skeptic is not necessarily an atheist or agnostic. In the confrontation between Catholicism and the Protestant Reformation, Erasmus of Rotterdam used skepticism about our ability to discover religious truth to argue for fidelity to the established church. Historically, religious skepticism has had strong connections to philosophical skepticism (see above).
The issue raised by religious skepticism is essential to our understanding of reality, or ontology, as well as to what we deem to be reliable knowledge. Since religious utterances are by nature, in most cases, about that which cannot be known through our physical senses, the question that arises is about the criteria that would allow us to make such statements in the first place. Theological statements will generally be based on belief in the reliability of revelation as transmitted through holy scriptures and originating with otherworldly experiences by holy men and women (founders of religions). Tradition and institutions are also generally acknowledged sources of religious certainty. None of these, however, involve the process of cognition in the ordinary sense; hence they easily become the target of skeptical attacks. The challenge can come from skeptically inclined individuals. It can also materialize in thought movements and even in the atmosphere of entire periods in history, such as the eighteenth-century Enlightenment, notably in France.
A further source of religious certainty is that which can broadly be defined as mysticism and consists in a perceived direct contact with the otherworldly reality. Such claims are experiential, rather than theoretical in nature. The skeptical position towards such claims will generally be to acknowledge the reality of any particular mystical experience, but to explain it away as mere self-deception or as a mental problem. A softer form of religious skepticism would be to suspend judgment based on one’s inability to verify the validity of religious beliefs and the significance of so-called spiritual phenomena.
Activist skeptics, self-described "debunkers" are a subset of empirical skeptics who aim to expose in public what they see as the truth behind specific extraordinary claims. Debunkers may publish books, air TV programs, create websites, or use other means to advocate their message. In some cases they may challenge claimants outright or even stage elaborate hoaxes to prove their point.
Because debunkers often attack popular ideas, many are not strangers to controversy. Critics of debunkers sometimes accuse them of robbing others of hope. Debunkers frequently reply that it is the claimant, whom they many times accuse of exploiting public gullibility, who is guilty of abuse.
Habitual debunkers, especially those who intentionally rely on pseudoscience masquerading as empirical skepticism, are sometimes called pseudoskeptics or pathological skeptics.
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