For a more general discussion of skepticism, please look at:
Philosophical skepticism (UK spelling scepticism; from Greek
σκέψις skepsis, "inquiry") is a philosophical school of thought
that questions the possibility of certainty in knowledge. Skeptic
philosophers from different historical periods adopted different
principles and arguments, but their ideology can be generalized as
either (1) the denial of possibility of all knowledge or (2) the
suspension of judgement due to the inadequacy of evidence.
Philosophy of Skepticism
Epistemology and skepticism
1.3 Criticism of skepticism
1.4 Skeptical hypotheses
2 History of Western Tradition of Skepticism
Ancient Greek skepticism
2.1.1 Sextus Empiricus
2.1.2 Augustine's Proof Against Skepticism
2.2 Skepticism's Revival in the Sixteenth Century
Michel de Montaigne
Michel de Montaigne (1533-1592)
Marin Mersenne (1588–1648)
Skepticism in the Seventeenth Century
Thomas Hobbes (1588-1679)
Spinoza and Religious
Pierre Bayle (1647-1706)
2.4 Kant's skepticism and its influence on German philosophy
2.5 Emerging Discussion after the Death of Richard Popkin
3 History of
Skepticism in Non-Western Philosophy
3.1 Ancient Indian skepticism
3.2 Ancient Chinese philosophy
Zhuang Zhou (~369-286 BC)
Wang Chong (27– ~100 AD)
3.3 Medieval Arabic philosophy
3.4 Aztec philosophy
4 See also
6 Further reading
7 External links
Philosophy of Skepticism
Skepticism is not a single position but covers a range of different
positions. In the ancient world there were two main skeptical
Academic skepticism took the dogmatic position that
knowledge was not possible; Pyrrhonian skeptics refused to take a
dogmatic position on any issue—including skepticism. Radical
skepticism ends in the paradoxical claim that one cannot know
anything—including that one cannot know about knowing anything.
Skepticism can be classified according to its scope. Local skepticism
involves being skeptical about particular areas of knowledge, e.g.
moral skepticism, skepticism about the external world, or skepticism
about other minds, whereas global skepticism is skeptical about the
possibility of any knowledge at all.
Skepticism can also be classified according to its method. In the
Western tradition there are two basic approaches to skepticism.
Cartesian skepticism —named somewhat misleadingly after René
Descartes, who was not a skeptic but used some traditional skeptical
arguments in his Meditations to help establish his rationalist
approach to knowledge— attempts to show that any proposed knowledge
claim can be doubted. Agrippan skepticism focuses on the process of
justification rather than the possibility of doubt. According to this
view there are three ways in which one might attempt to justify a
claim but none of them are adequate: one can keep on providing further
justification but this leads to an infinite regress; one can stop at a
dogmatic assertion; or one can argue in circular reasoning, never
reaching a viable conclusion.
Philosophical skepticism is distinguished from methodological
skepticism in that philosophical skepticism is an approach that
questions the possibility of certainty in knowledge, whereas
methodological skepticism is an approach that subjects all knowledge
claims to scrutiny with the goal of sorting out true from false
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. Some skeptics have gone further and claimed
that true knowledge is impossible, for example the Academic school in
Ancient Greece well after the time of Carneades. A third skeptical
approach would be neither to accept nor reject the possibility of
Skepticism can be either about everything or about particular areas. A
'global' skeptic argues that he does not absolutely know anything to
be either true or false. Academic global skepticism has great
difficulty in supporting this claim while maintaining philosophical
rigor, since it seems to require that nothing can be known—except
for the knowledge that nothing can be known, though in its
probabilistic form it can use and support the notion of weight of
evidence. Thus, some probabilists avoid extreme skepticism by
maintaining that they merely are 'reasonably certain' (or 'largely
believe') some things are real or true. As for using probabilistic
arguments to defend skepticism, in a sense this enlarges or increases
scepticism, while the defence of empiricism by Empiricus weakens
skepticism and strengthens dogmatism by alleging that sensory
appearances are beyond doubt. Much later, Kant would re-define
"dogmatism" to make indirect realism about the external world seem
objectionable. While many Hellenists, outside of Empiricus, would
maintain that everyone who is not sceptical about everything is a
dogmatist, this position would seem too extreme for most later
Nevertheless, A Pyrrhonian global skeptic labors under no such modern
constraint, since he only alleged that he, personally, did not know
anything and made no statement about the possibility of knowledge. Nor
Arcesilaus feel bound, since he merely corrected Socrates's "I
only know that I know nothing" by adding "I don't even know that",
thus more fully rejecting dogmatism.
Local skeptics deny that people do or can have knowledge of a
particular area. They may be skeptical about the possibility of one
form of knowledge without doubting other forms. Different kinds of
local skepticism may emerge, depending on the area. A person may doubt
the truth value of different types of journalism, for example,
depending on the types of media they trust.
In Islamic philosophy, skepticism was established by Al-Ghazali
(1058–1111), known in the West as "Algazel", as part of the Ash'ari
school of Islamic theology.
That Nothing is Known (published in 1581 as Quod
nihil scitur) is one of the crucial texts of Renaissance
Epistemology and skepticism
Skepticism, as an epistemological argument, poses the question of
whether knowledge, in the first place, is possible. Skeptics argue
that the belief in something does not necessarily justify an assertion
of knowledge of it. In this, skeptics oppose dogmatic foundationalism,
which states that there have to be some basic positions that are
self-justified or beyond justification, without reference to others.
(One example of such foundationalism may be found in Spinoza's
Ethics.) The skeptical response to this can take several approaches.
First, claiming that "basic positions" must exist amounts to the
logical fallacy of argument from ignorance combined with the slippery
Among other arguments, skeptics used Agrippa's trilemma, named after
Agrippa the Sceptic, to claim no certain belief could be achieved.
Foundationalists have used the same trilemma as a justification for
demanding the validity of basic beliefs.
This skeptical approach is rarely taken to its pyrrhonean extreme by
most practitioners. Several modifications have arisen over the years,
including the following :
Fictionalism would not claim to have knowledge but will adhere to
conclusions on some criterion such as utility, aesthetics, or other
personal criteria without claiming that any conclusion is actually
Philosophical fideism (as opposed to religious Fideism) would assert
the truth of some propositions, but does so without asserting
Some forms of pragmatism would accept utility as a provisional guide
to truth but not necessarily a universal decision-maker.
There are two different categories of epistemological skepticism,
which can be referred to as mitigated and unmitigated skepticism. The
two forms are contrasting but are still true forms of skepticism.
Mitigated skepticism does not accept "strong" or "strict" knowledge
claims but does, however, approve specific weaker ones. These weaker
claims can be assigned the title of "virtual knowledge", but must be
to justified belief. Unmitigated skepticism rejects both claims of
virtual knowledge and strong knowledge. Characterising knowledge as
strong, weak, virtual or genuine can be determined differently
depending on a person's viewpoint as well as their characterisation of
Criticism of skepticism
Most philosophies have weaknesses and can be criticized and this is a
general principle of progression in philosophy. The philosophy of
skepticism asserts that no truth is knowable or only probable.
Some say the scientific method also asserts probable findings, because
the number of cases tested is always limited and they constitute
perceptual observations. Another criticism is the proposition that
“no truth is knowable” is knowably true is contradictory. The
here is one hand argument is also another relatively simple criticism
that reverses the skeptic's proposals and supports common sense.
Pierre Le Morvan (2011) has distinguished between three broad
philosophical approaches to skepticism. The first he calls the
"Foil Approach." According to the latter, skepticism is treated as a
problem to be solved, or challenge to be met, or threat to be parried;
skepticism‘s value on this view, insofar as it is deemed to have
one, accrues from its role as a foil contrastively illuminating what
is required for knowledge and justified belief. The second he calls
the "Bypass Approach" according to which skepticism is bypassed as a
central concern of epistemology. Le Morvan advocates a third
approach—he dubs it the "Health Approach"—that explores when
skepticism is healthy and when it is not, or when it is virtuous and
when it is vicious.
A skeptical hypothesis is a hypothetical situation which can be used
in an argument for skepticism about a particular claim or class of
claims. Usually the hypothesis posits the existence of a deceptive
power that deceives our senses and undermines the justification of
knowledge otherwise accepted as justified. Skeptical hypotheses have
received much attention in modern Western philosophy.
The first skeptical hypothesis in modern
Western philosophy appears in
René Descartes' Meditations on First Philosophy. At the end of the
first Meditation Descartes writes: "I will suppose... that some evil
demon of the utmost power and cunning has employed all his energies to
The "brain in a vat" hypothesis is cast in scientific terms. It
supposes that one might be a disembodied brain kept alive in a vat,
and fed false sensory signals, by a mad scientist.
The "dream argument" of Descartes and Zhuangzi supposes reality to be
indistinguishable from a dream.
Descartes' evil demon is a being "as clever and deceitful as he is
powerful, who has directed his entire effort to misleading me".
The five minute hypothesis (or omphalos hypothesis or Last
Thursdayism) suggests that the world was created recently together
with records and traces indicating a greater age.
The simulated reality hypothesis or "Matrix hypothesis" suggest that
everyone, or even the entire universe, might be inside a computer
simulation or virtual reality.
History of Western Tradition of Skepticism
Ancient Greek skepticism
The Western tradition of systematic skepticism goes back at least as
Elis (b. circa 360 BCE). However, "The 5th century
sophists develop forms of debate which are ancestors of skeptical
argumentation. They take pride in arguing in a persuasive fashion for
both sides of an issue." There were many disputes that could be
found within the philosophical schools of his day, and according to a
later account of his life by his student Timon of Phlius, Pyrrho
extolled a way to become happy and tranquil.
"Whoever wants to live well (eudaimonia) must consider these three
questions: First, how are pragmata (ethical matters, affairs, topics)
by nature? Secondly, what attitude should we adopt towards them?
Thirdly, what will be the outcome for those who have this attitude?"
Pyrrho's answer is that "As for pragmata they are all adiaphora
(undifferentiated by a logical differentia), astathmēta (unstable,
unbalanced, not measurable), and anepikrita (unjudged, unfixed,
undecidable). Therefore, neither our sense-perceptions nor our doxai
(views, theories, beliefs) tell us the truth or lie; so we certainly
should not rely on them. Rather, we should be adoxastous (without
views), aklineis (uninclined toward this side or that), and
akradantous (unwavering in our refusal to choose), saying about every
single one that it no more is than it is not or it both is and is not
or it neither is nor is not.
The main principle of Pyrrho's thought is expressed by the word
acatalepsia, which connotes the ability to withhold assent from
doctrines regarding the truth of things in their own nature; against
every statement its contradiction may be advanced with equal
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 idea
was to produce in the student a state of indifference towards ideas
about non-evident matters. Since no one can observe or otherwise
experience causation, external world (its "externality"), ultimate
purpose of the universe or life, justice, divinity, soul, etc., they
declared no need to believe in such things. The Pyrrhonists pointed
out that, despite claims that such notions were necessary, some people
ignorant of them get by just fine before learning about them. They
further noted that science does not require belief and that faith in
intelligible realities is different from pragmatic convention for the
sake of experiment. For each intuitive notion (e.g. the existence of
an external world), the Pyrrhonists cited a contrary opinion to negate
it. They added that consensus indicates neither truth nor even
Pyrrho's thinking subsequently influenced Plato's Academy, creating
Academic skepticism of the New or Middle Academy,
315 – 241 BCE) and
Carneades (c. 213–129 BCE) argued from Stoic
premises that the Stoics were actually committed to denying the
possibility of knowledge, but seemed to maintain nothing themselves,
but Clitomachus, a student of Carneades, interpreted his teacher's
philosophy as suggesting an early probabilistic account of knowledge.
The Roman politician and philosopher, Cicero, also seems to have been
a supporter of the probabilistic position attributed to the Middle
Academy, even if the return to a more dogmatic orientation of that
school was already beginning to take place.
Diogenes Laërtius lists ten modes of reasoning which Pyrrhonists
thought justified their position:
Some things give animals pleasure which give other animals pain. What
is useful to one animal is harmful to another.
Each human has a different assortment of preferences, abilities and
Each sense gives a different impression of the same object.
There is no reason to think one is sane while others are insane—the
opposite could be true.
Cultures disagree regarding beauty, truth, goodness, religion, life
There is no consistency in perception. (His examples were that the
color purple will show different tints depending on the lighting, a
person looks different between noon and sunset, and a very heavy rock
on land is lighter when in water)
The senses can be shown to be deceptive. (From a distance, the square
tower looks round and the sun looks small)
Things that strengthen in moderation will weaken when taken in excess,
like wine and food.
When a thing is rare, it surprises people. When a thing is common, it
does not surprise people.
Inter-relations among things are of course relative, and by themselves
are unknowable. (e.g. to know 'parent' you must know 'child,' and to
know 'child' you must know 'parent.' Neither can be known by itself.)
In the centuries to come, the words Academician and Pyrrhonist would
often be used to mean generally skeptic, often ignoring historical
changes and distinctions between denial of knowledge and avoidance of
belief, between degree of belief and absolute belief, and between
possibility and probability.
Sextus Empiricus (c. 200 CE), the main authority for Pyrrhonian
skepticism, worked outside the Academy, which by his time had ceased
to be a skeptical or probabilistic school, and argued in a different
direction, incorporating aspects of empiricism into the basis for
evaluating knowledge, but without the insistence on experience as the
absolute standard of it. Sextus' empiricism was limited to the
"absolute minimum" already mentioned — that there seem to be
appearances. He developed this basic thought of Pyrrho's into lengthy
arguments, most of them directed against Stoics and Epicureans, but
also the Academic skeptics. The common anti-skeptical argument is that
if one knows nothing, one cannot know that one knows nothing, and so
may know something after all. It is worth noting that such an argument
only succeeds against the complete denial of the possibility of
knowledge. Considering dogmatic the claims both to know and not to
know, Sextus and his followers claimed neither. Instead, despite the
apparent conflict with the goal of ataraxia, they claimed to continue
searching for something that might be knowable.
Empiricus, as the most systematic author of the works by Hellenistic
sceptics which have survived, noted that there are at least ten modes
of skepticism. These modes may be broken down into three categories:
one may be skeptical of the subjective perceiver, of the objective
world, and the relation between perceiver and the world. His
arguments are as follows.
Subjectively, both the powers of the senses and of reasoning may vary
among different people. And since knowledge is a product of one or the
other, and since neither are reliable, knowledge would seem to be in
trouble. For instance, a color-blind person sees the world quite
differently from everyone else. Moreover, one cannot even give
preference on the basis of the power of reason, i.e., by treating the
rational animal as a carrier of greater knowledge than the irrational
animal, since the irrational animal is still adept at navigating their
environment, which suggests the ability to "know" about some aspects
of the environment.
Secondly, the personality of the individual might also influence what
they observe, since (it is argued) preferences are based on
sense-impressions, differences in preferences can be attributed to
differences in the way that people are affected by the object.
Third, the perceptions of each individual sense seemingly have nothing
in common with the other senses: i.e., the color "red" has little to
do with the feeling of touching a red object. This is manifest when
our senses "disagree" with each other: for example, a mirage presents
certain visible features, but is not responsive to any other kind of
sense. In that case, our other senses defeat the impressions of sight.
But one may also be lacking enough powers of sense to understand the
world in its entirety: if one had an extra sense, then one might know
of things in a way that the present five senses are unable to advise
us of. Given that our senses can be shown to be unreliable by
appealing to other senses, and so our senses may be incomplete
(relative to some more perfect sense that one lacks), then it follows
that all of our senses may be unreliable. (Empiricus:58)
Fourth, our circumstances when one perceives anything may be either
natural or unnatural, i.e., one may be either in a state of
wakefulness or sleep. But it is entirely possible that things in the
world really are exactly as they appear to be to those in unnatural
states (i.e., if everything were an elaborate dream). (Empiricus:59)
One can have reasons for doubt that are based on the relationship
between objective "facts" and subjective experience. The positions,
distances, and places of objects would seem to affect how they are
perceived by the person: for instance, the portico may appear tapered
when viewed from one end, but symmetrical when viewed at the other;
and these features are different. Because they are different features,
to believe the object has both properties at the same time is to
believe it has two contradictory properties. Since this is absurd, one
must suspend judgment about what properties it possesses due to the
contradictory experiences. (Empiricus:63)
One may also observe that the things one perceives are, in a sense,
polluted by experience. Any given perception—say, of a chair—will
always be perceived within some context or other (i.e., next to a
table, on a mat, etc.) Since this is the case, one often only speaks
of ideas as they occur in the context of the other things that are
paired with it, and therefore, one can never know of the true nature
of the thing, but only how it appears to us in context. (Empiricus:
Along the same lines, the skeptic may insist that all things are
relative, by arguing that:
Absolute appearances either differ from relative appearances, or they
If absolutes do not differ from relatives, then they are themselves
But if absolutes do differ from relatives, then they are relative,
because all things that differ must differ from something; and to
"differ" from something is to be relative to something. (Empiricus:67)
Finally, one has reason to disbelieve that one knows anything by
looking at problems in understanding objects by themselves. Things,
when taken individually, may appear to be very different from when
they are in mass quantities: for instance, the shavings of a goat's
horn are white when taken alone, yet the horn intact is black.
Augustine's Proof Against Skepticism
Augustine of Hippo
In 386 CE, Augustine published Contra Academicos (Against the
Skeptics), which counters many claims that Academic Skeptics make:
Objection from Error: Through logic, Augustine proves that Skepticism
does not lead to happiness like the academic skeptics claim. His proof
is summarized below.
A wise man lives according to reason, and thus is able to be happy.
One who is searching for knowledge but never finds it is in error.
Imperfection objection: People in error are not happy, because being
in error is an imperfection, and people cannot be happy with an
Conclusion: One who is still seeking knowledge cannot be
Error of Non-Assent: Augustine's proof that suspending belief does not
fully prevent one from error. His proof is summarized below.
Introduction of the error: Let P be true. If a person fails to believe
P due to suspension of belief in order to avoid error, the person is
also committing an error.
The Anecdote of the Two Travelers: Travelers A and B are trying to
reach the same destination. At a fork in the road, a poor shepherd
tells them to go left. Traveler A immediately believes him and reaches
the correct destination. Traveler B suspends belief, instead believing
in the advice of a well-dressed townsman to go right, because his
advice seems more persuasive. However, the townsman is actually a
samardocus (con man) so Traveler B never reaches the correct
The Anecdote of the Adulterer: A man suspends belief that adultery is
bad, and commits adultery with another man's wife because it is
persuasive to him. Under Academic Skepticism, this man cannot be
charged because he acted on what was persuasive to him without
Conclusion: Suspending belief exposes individuals to an error as
defined by the Academic Skeptics.
Skepticism's Revival in the Sixteenth Century
Michel de Montaigne
Michel de Montaigne (1533-1592)
Michel de Montaigne
The most notable figure of the
Skepticism revival in the 1500s,
Montaigne wrote about his studies of Academic
Pyrrhonism through his Essais.
His most notable writings on
Skepticism occurred in an essay written
mostly in 1575-1576, "Apologie de Raimond Sebond," when he was reading
Sextus Empiricus and trying to translate Raimond Sebond's writing,
including his proof of Christianity's natural existence. The reception
to Montaigne's translations included some criticisms of Sebond's
proof. Montaigne responded to some of them in Apologie, including a
defense for Sebond's logic that is skeptical in nature and similar to
Pyrrhonism. His refutation is as follows:
Critics claiming Sebond's arguments are weak show how egoistic humans
believe that their logic is superior to others.
Many animals can be observed to be superior to humans in certain
respects. To argue this point, Montaigne even writes about dogs who
are logical and creates their own syllogisms to understand the world
around them. This was an example used in Sextus Empiricus.
Since animals also have rationality, the over-glorification of man's
mental capabilities is a trap—man's folly. One man's reason cannot
be assuredly better than another's as a result.
Ignorance is even recommend by religion so that an individual can
reach faith through obediently following divine instructions to learn,
not by one's logic.
Marin Mersenne (1588–1648)
Mersenne was an author, a mathematician, a scientist, and a
philosopher. He wrote in defense of science and
atheists and Pyrrhonists before retiring to encourage development of
science and the "new philosophy," which includes philosophers like
Gassendi, Descartes, Galileo, and Hobbes. A major work of his in
Skepticism is La Verité des Sciences, in which he argues
that although we may not be able to know the true nature of things, we
can still formulate certain laws and rules for sense-perceptions
Additionally, he points out that we do not doubt everything because:
Humans do agree about some things, for example, an ant is smaller than
There are natural laws governing our sense-perceptions, such as
optics, which allow us to eliminate inaccuracies
Man created tools such as rulers and scales to measure things and
eliminate doubts such as bent oars, pigeons’ necks, and round
A Pyrrhonist might refute these points by saying that senses deceive,
and thus knowledge turns into infinite regress or circular logic. Thus
Mersenne argues that this cannot be the case, since commonly agreed
upon rules of thumb can be hypothesized and tested over time to ensure
that they continue to hold.
Furthermore, if everything can be doubted, the doubt can also be
doubted, so on and so forth. Thus, according to Mersenne, something
has to be true. Finally, Mersenne writes about all the mathematical,
physical, and other scientific knowledge that is true by repeated
testing, and has practical use value. Notably, Mersenne was one of the
few philosophers who accepted Hobbes' radical ideology—he saw it as
a new science of man.
Skepticism in the Seventeenth Century
Thomas Hobbes (1588-1679)
During his long stay in Paris,
Thomas Hobbes was actively involved in
the circle of major skeptics like Gassendi and Mersenne who focus on
the study of skepticism and epistemology. Unlike his fellow skeptic
friends, Hobbes never treated skepticism as a main topic for
discussion in his works. Nonetheless, Hobbes was still labeled as a
religious skeptic by his contemporaries for raising doubts about
Mosaic authorship of the
Pentateuch and his political and
psychological explanation of the religions. Although Hobbes himself
did not go further to challenge other religious principles, his
suspicion for the
Mosaic authorship did siginificant damage to the
religious traditions and paved the way for later religious skeptics
Isaac La Peyrère
Isaac La Peyrère to further question some of the
fundamental beliefs of the Judeo-Christian religious system. Hobbes'
answer to skepticism and epsitmology was innvatively political: he
believed that moral knowledge and religious knowledge were in their
nature relative, and there was no absolute standard of truth governing
them. As a result, it was out of political reasons that certain truth
standards about religions and ethics were devised and established in
order to form functioning government and stable
Spinoza and Religious
Spinoza was among the first European philosophers who were
religious skeptics. He was quite familiar with the philosophy of
DesCartes and unprecedentedly extended the application of the
Cartesian method to the religious context by analyzing religious texts
Spinoza sought to dispute the knowledge-claims of the
Judeo-Charitian-Islamic religious system by examining its two
Scripture and the Miracles. He claimed that all
Cartesian knowledge, or the rational knowledge should be accessible to
the entire population. Therefore, the Scriptures, aside from those by
Jesus, should not be considered the secret knowledge attained from God
but just the imagination of the prophets. The Scriptures, as a result
of this claim, could not serve as a base for knowledge and were
reduced to simple ancient historical texts. Moreover,
rejected the possibility for the Miracles by simply asserting that
people only considered them miraculous due to their lack of
understanding of the nature. By rejecting the validity of the
Scriptures and the Miracles,
Spinoza demolished the foundation for
religious knowledge-claim and established his understanding of the
Cartesian knowledge as the sole authority of knowledge-claims. Despite
being deeply-skeptical of the religions,
Spinoza was in fact
exceedingly anti-skeptical towards reason and rationality. He
steadfastly confirmed the legitimacy of reason by associating it with
the acknowledgement of God, and thereby skepticism with the rational
approach to knowledge was not due to problems with the rational
knowledge but from the fundamental lack of understanding of God.
Spinoza's religious skepticism and anti-skepticism with reason thus
helped him transform epistemology by separating the theological
knowledge-claims and the rational knowledge-claims.
Pierre Bayle (1647-1706)
Pierre Bayle by Louis Ferdinand Elle
Pierre Bayle was a French philosopher in the late 17th century that
was described by
Richard Popkin to be a "supersceptic" who carried out
the sceptic tradition to the extreme. Bayle was born in a Calvnist
family in Carla-Bayle, and during the early stage of his life, he
converted into Catholicism before returning to Calvinism. This
conversion between religions caused him to leave France for the more
religiously tolerant Holland where he stayed and worked for the rest
of his life.
Bayle believed that truth cannot be obtained through reason and that
all human endeavor to acquire absolute knowledge would inevitably lead
to failure. Bayle's main approach was highly skeptical and
destructive: he sought to examine and analyze all existing theories in
all fields of human knowledge in order to show the faults in their
reasoning and thus the absurdity of the theories themselves. In his
Dictionnaire Historique et Critique (Historical and
Critical Dictionary), Bayle painstakingly identified the logical flaws
in several works throughout the history in order to emphasize the
absolute futility of rationality. Bayle's complete nullification of
reason led him to conclude that faith is the final and only way to
Bayle's real intention behind his extremely destructive works remained
controversial. Some described him to be a Fideist, while others
speculated him to be a secret Atheist. However, no matter what his
original intention was, Bayle did cast significant influence on the
Age of Enlightenment
Age of Enlightenment with his destruction of some of the most
essential theological ideas and his justification of religious
Atheism in his works.
Kant's skepticism and its influence on German philosophy
See also: Salomon Maimon
Immanuel Kant (1724–1804) tried to provide a ground for empirical
science against David Hume's skeptical treatment of the notion of
cause and effect. Hume (1711–1776) argued that for the notion of
cause and effect no analysis is possible which is also acceptable to
the empiricist program primarily outlined by John Locke
(1632–1704). But, Kant's attempt to give a ground to knowledge
in the empirical sciences at the same time cut off the possibility of
knowledge of any other knowledge, especially what Kant called
"metaphysical knowledge". So, for Kant, empirical science was
legitimate, but metaphysics and philosophy was mostly illegitimate.
The most important exception to this demarcation of the legitimate
from the illegitimate was ethics, the principles of which Kant argued
can be known by pure reason without appeal to the principles required
for empirical knowledge. Thus, with respect to metaphysics and
philosophy in general (ethics being the exception), Kant was a
skeptic. This skepticism as well as the explicit skepticism of G. E.
Schulze gave rise to a robust discussion of skepticism in
classical German philosophy, especially by Hegel. Kant's idea was
that the real world (the noumenon or thing-in-itself) was inaccessible
to human reason (though the empirical world of nature can be known to
human understanding) and therefore we can never know anything about
the ultimate reality of the world.
Hegel argued against Kant that
although Kant was right that using what
Hegel called "finite" concepts
of "the understanding" precluded knowledge of reality, we were not
constrained to use only "finite" concepts and could actually acquire
knowledge of reality using "infinite concepts" that arise from
Emerging Discussion after the Death of Richard Popkin
Richard Popkin was one of the founding fathers of study in
this area, the account of the history of
Skepticism in his books are
accepted as the standard. However, recent scholars have been
suggesting an addition to Popkin's account. Instead of centering the
Skepticism around specific figures who wrote key skeptical
Skepticism is proposed to be a continuous engagement with works
by ancients like
Sextus Empiricus to modern thinkers like Hume. The
engagement with previous works were probably due to unwanted doubts
about accepted episteme instead of purely due to classical writings
becoming available at any specific time.
Skepticism in Non-Western Philosophy
Ancient Indian skepticism
Indian skepticism towards dogmatic statements is illustrated by the
famous tale of the Blind men and an elephant, common in Buddhism and
Main article: Ajñana
Ajñana (literally 'non-knowledge') were the skeptical school of
ancient Indian philosophy. It was a śramaṇa movement and a major
rival of early Buddhism and Jainism. They have been recorded in
Buddhist and Jain texts. They held that it was impossible to obtain
knowledge of metaphysical nature or ascertain the truth value of
philosophical propositions; and even if knowledge was possible, it was
useless and disadvantageous for final salvation.
The historical Buddha asserted certain doctrines as true, such as the
possibility of nirvana, however he also upheld a form of skepticism
with regards to certain questions which he left "un-expounded"
(avyākata) and some he saw as "incomprehensible" (acinteyya). Because
the Buddha saw these questions (which tend to be of metaphysical
topics) as unhelpful on the path and merely leading to confusion and
"a thicket of views", he promoted suspension of judgment towards them.
This allowed him to carve out an epistemic middle way between what he
saw as the extremes of claiming absolute objectivity (associated with
the claims to omniscience of the Jain Mahavira) and extreme skepticism
(associated with the
Ajñana thinker Sanjaya Belatthiputta).
Philosophy remained highly skeptical of Indian
metaphysical arguments. The Buddhist philosopher
particular has been seen as the founder of the
which has been in turn compared with Greek Skepticism. Nagarjuna's
statement that he has "no thesis" (pratijña) has parallels in the
Sextus Empiricus of having "no position". Nagarjuna
famously opens his magnum opus, the Mulamadhyamakakarika, with the
statement that the Buddha claimed that true happiness was found
through dispelling 'vain thinking' (prapañca, also "conceptual
According to Richard P. Hayes, the Buddhist philosopher
also a kind of skeptic, which is in line with most early Buddhist
philosophy. Hayes writes:
...in both early Buddhism and in the Skeptics one can find the view
put forward that man's pursuit of happiness, the highest good, is
obstructed by his tenacity in holding ungrounded and unnecessary
opinions about all manner of things. Much of Buddhist philosophy, I
shall argue, can be seen as an attempt to break this habit of holding
on to opinions.
Scholars like Adrian Kuzminski have argued that
365–270) might have been influenced by Indian Buddhists during his
journey with Alexander the Great.
Cārvāka (Sanskrit: चार्वाक) school of materialism,
also known as Lokāyata, is a distinct branch of Indian philosophy.
The school is named after Cārvāka, author of the
Bārhaspatya-sūtras and was founded in approximately 500 BC.
Cārvāka is classified as a "heterodox" (nāstika) system,
characterized as a materialistic and atheistic school of thought. This
school was also known for being strongly skeptical of the claims of
Indian religions, such as reincarnation and karma.
Anekantavada and Syadvada
Jain philosophy claims that is it possible to achieve
omniscience, absolute knowledge (Kevala Jnana), at the moment of
enlightenment, their theory of anekāntavāda or 'many sided-ness',
also known as the principle of relative pluralism, allows for a
practical form of skeptical thought regarding philosophical and
religious doctrines (for un-enlightened beings, not all-knowing
According to this theory, the truth or the reality is perceived
differently from different points of view, and that no single point of
view is the complete truth. Jain doctrine states that, an
object has infinite modes of existence and qualities and, as such,
they cannot be completely perceived in all its aspects and
manifestations, due to inherent limitations of the humans.
Anekāntavāda is literally the doctrine of non-onesidedness or
manifoldness; it is often translated as "non-absolutism". Syādvāda
is the theory of conditioned predication which provides an expression
to anekānta by recommending that epithet “Syād” be attached to
Syādvāda is not only an extension of Anekānta
ontology, but a separate system of logic capable of standing on its
own force. As reality is complex, no single proposition can express
the nature of reality fully. Thus the term “syāt” should be
prefixed before each proposition giving it a conditional point of view
and thus removing any dogmatism in the statement. For Jains, fully
enlightened beings are able to see reality from all sides and thus
have ultimate knowledge of all things. This idea of omniscience was
criticized by Buddhists such as Dharmakirti.
Ancient Chinese philosophy
A Painting of Zhuangzi and his Butterfly Dream
Zhuang Zhou (~369-286 BC)
Zhuang Zhou (庄子，"Master Zhuang") was a famous ancient Chinese
Taoism philospher during the
Hundred Schools of Thought
Hundred Schools of Thought period. Zhuang
Zhou demonstrated his skeptical thinking through several anecdotes in
the preeminent work Zhuangzi that was attributed to him:
"The Debate on the Joy of Fish" (知鱼之乐) : In this
Zhuang Zhou argued with his fellow philosopher
Hui Shi on if
they knew the fish in the pond was happy or not, and
Zhuang Zhou said
the famous sentence that "You are not I. How do you know that I do not
know that the fish are happy?"  ( Autumn Floods 秋水篇,
"The Butterfly of the Dream"(周公梦蝶) : The paradox of
"Butterfly Dream" described Zhuang Zhou's confusion after dreaming
himself to be a butterfly: "But he didn't know if he was Zhuang Zhou
who had dreamt he was a butterfly, or a butterfly dreaming that he was
Zhuang Zhou."  (Discussion on Making All Things Equal 齐物篇,
Through these anecdotes in Zhuangzi,
Zhuang Zhou indicated his belief
in the limitation of language and human communication and the
inaccessibility of universal truth which established himself as an
Zhuang Zhou was by no means a radical skeptic, since he
only applied skeptical methods partially in some of his arguments to
Taoism beliefs while adopting these
Taoism beliefs in
a dogmatic fashion.
Wang Chong (27– ~100 AD)
Wang Chong (王充) was the leading figure of the skeptic branch of
Confucianism school in China during the first century A.D. He
introduced a method of rational critique and applied it to the
wide-spread dogmatism thinking of his age like phenomenology (the main
Confucianism ideology that linked all natural phenomenons
with human ethics), state-led cults, and popular superstition. His own
philosophy incorporated both
Confucianism thinkings, and it
was based on a secular, rational practice of developing hypotheses
based on natural events to explain the universe which exemplified a
form of naturalism that resembled the philosophical idea of Epicureans
Medieval Arabic philosophy
Islamic theology and Islamic philosophy, the scholar Al-Ghazali
(1058–1111) is considered a pioneer of methodic doubt and
skepticism.[not in citation given] His 11th century book titled
The Incoherence of the Philosophers
The Incoherence of the Philosophers marks a major turn in Islamic
epistemology, as Ghazali effectively discovered a methodic form of
philosophical skepticism that would not be commonly seen in the West
until René Descartes,
George Berkeley and David Hume. The encounter
with skepticism led Ghazali to embrace a form of theological
occasionalism, or the belief that all causal events and interactions
are not the product of material conjunctions but rather the immediate
and present will of God. While he himself was a critic of the
philosophers, Ghazali was a master in the art of philosophy and had
immensely studied the field. After such a long education in
philosophy, as well as a long process of reflection, he had criticized
the philosophical method.
The autobiography Ghazali wrote towards the end of his life, The
Deliverance From Error (Al-munqidh min al-ḍalāl; several English
translations) is considered a work of major importance. In it,
Ghazali recounts how, once a crisis of epistemological skepticism was
resolved by "a light which God Most High cast into my breast...the key
to most knowledge," he studied and mastered the arguments of
Kalam, Islamic philosophy, and Ismailism. Though appreciating what was
valid in the first two of these, at least, he determined that all
three approaches were inadequate and found ultimate value only in the
mystical experience and spiritual insight (Spiritual intuitive thought
– Firasa and Nur) he attained as a result of following Sufi
practices. William James, in Varieties of Religious Experience,
considered the autobiography an important document for "the purely
literary student who would like to become acquainted with the
inwardness of religions other than the Christian", comparing it to
recorded personal religious confessions and autobiographical
literature in the Christian tradition.
Scholars have noted the similarities between Descartes' Discourse on
Method and Ghazali's work and the writer
George Henry Lewes
George Henry Lewes went
even further by claiming that "had any translation of it [The Revival
of Religious Sciences] in the days of Descartes existed, everyone
would have cried out against the plagiarism."[not in citation
Aztec philosophy suggest that the elite classes believed
in an essentially panentheistic worldview, in which teotl represents
an unified, underlying universal force. Human beings cannot truly
perceive teotl due to its chaotic, constantly changing nature, just
the "masks"/facets it is manifested as.
Brain in a vat
Five minute hypothesis
Problem of the criterion
Problem of induction
Trivialism (opposite of skepticism)
^ a b c d e f g h i 1923-, Popkin, Richard Henry, (2003). The history
of scepticism : from Savonarola to Bayle. Popkin, Richard Henry,
1923- (Rev. and expanded ed ed.). Oxford: Oxford University Press.
ISBN 9780195355390. OCLC 65192690. CS1 maint: Extra
^ Williams, Michael (2001). "Chapter 5: Agrippa's Trilemma". Problems
of Knowledge: A Critical Introduction to Epistemology. Oxford
University Press. p. 61. ISBN 978-0192892560.
^ Francisco Sanchez, That Nothing is Known, Cambridge University
^ a b "SKEPTICISM". Encyclopedia of Empiricism. 1997.
access-date= requires url= (help)
^ Popkin, H and Stroll, A.
Philosophy Made Simple’’ Broadway
Books, NY, NY 1993
^ Kreeft, Peter & Tacelli, R. K Handbook of Christian Apologetics,
IVP Academic, Ill. 1994, p. 367
^ Popkin, p. 205
^ Popkin, p. 230
^ Kreeft p. 373
^ Stanford Encyclopedia of Philosophy: Ancient Skepticism.
^ Beckwith, Christopher I. (2015). Greek Buddha: Pyrrho's Encounter
with Early Buddhism in Central Asia (PDF). Princeton University Press.
pp. 22–23. ISBN 9781400866328.
Diogenes Laërtius 9:80–88
^ On the ten modes, see Sextus Empiricus. Outlines of Skepticism
^ a b 1962-, Dutton, Blake D.,. Augustine and academic
skepticism : a philosophical study. Ithaca.
ISBN 9781501703553. OCLC 951625897.
^ 1922-2012,, Hick, John, (). Classical and contemporary
readings in the philosophy of religion (2d ed ed.). Englewood Cliffs,
N.J.,: Prentice-Hall. ISBN 0131352695. OCLC 90682.
Check date values in: date= (help)CS1 maint: Extra text (link)
^ M.,, Clarke, Desmond. French philosophy, 1572-1675 (First edition
ed.). Oxford, United Kingdom. ISBN 9780198749578.
OCLC 923850410. CS1 maint: Extra text (link)
^ a b
Skepticism in the modern age : building on the work of
Richard Popkin. Maia Neto, José Raimundo, 1959-, Paganini, Gianni,
1950-, Laursen, John Christian.,
Skepticism from the
the Enlightenment: a Conference in Memory of Richard H. Popkin
(1923-2005) (2007 : Belo Horizonte, Brazil). Leiden: Brill. 2009.
ISBN 9789047431909. OCLC 700517388.
^ A companion to early modern philosophy. Nadler, Steven M., 1958-.
Malden, Mass.: Blackwell Pub. 2002. ISBN 0631218009.
^ Grotius to Gassendi. Chappell, V. C. (Vere Claiborne), 1930-. New
York: Garland Pub. 1992. ISBN 0815305761.
^ Missner, Marshall (1983). "
Skepticism and Hobbes's Political
Philosophy". Journal of the History of Ideas. 44 (3): 407–427.
^ Black, Sam (1997). "Science and Moral
Skepticism in Hobbes".
Canadian Journal of Philosophy. 27 (2): 173–207.
Skepticism and political thought in the seventeenth and eighteenth
centuries. Laursen, John Christian,, Paganini, Gianni, 1950-. Toronto.
ISBN 9781442649217. OCLC 904548214.
^ Batnitzky, Leora (December 2003). "SPINOZA'S CRITIQUE OF RELIGIOUS
AUTHORITY: SPINOZA'S CRITIQUE OF MIRACLES". Cardozo Law Review. 25: 57
– via ebscohost.
^ a b 1985-, Matytsin, Anton M.,. The specter of skepticism in the age
of Enlightenment. Baltimore. ISBN 9781421420523.
^ a b Lennon, Thomas M. (2002). "What Kind of a Skeptic Was Bayle?".
Midwest Studies In Philosophy. 26–1: 258–279 – via
^ David Hume,
A Treatise of Human Nature
A Treatise of Human Nature (1739),
Book I, "Of the
Understanding" and David Hume, An Enquiry Concerning Human
^ See G. E. Schulze, Aenesidemus (1792), excerpted in Between Kant and
Hegel: Texts in the Development of Post-Kantian Idealism, Translated
with Introductions by George di Giovanni and H. S. Harris,
Indianapolis, Indiana: Hackett Publishing, 2000. See also Frederick C.
Beiser, The Fate of Reason: German
Philosophy from Kant to Fichte,
Cambridge, Massachusetts: Harvard University Press, 1987; Chapter 9,
^ See (1) H. S. Harris, "Skepticism, Dogmatism and Speculation in the
Critical Journal" (1985), in Between Kant and Hegel: Texts in the
Development of Post-Kantian Idealism, Translated with Introductions by
George di Giovanni and H. S. Harris, Indianapolis, Indiana: Hackett
Publishing, 2000; (2) G. W. F. Hegel, "On the Relationship of
Skepticism to Philosophy, Exposition of its Different Modifications
and Comparison of the Latest Form with the Ancient One", Translated by
H. S. Harris, in di Giovanni and Harris (2000) (cited just above); and
(3) Michael N. Forster,
Hegel and Skepticism, Cambridge,
Massachusetts: Harvard University Press, 1989.
^ Georg Wilhelm Friedrich Hegel, The Encyclopedia
Logic (1830), § 28,
pp. 65–68, Translated by T. F. Garaets, W. A. Suchting, and H. S.
Harris, Indianapolis, Indiana: Hackett Publishing, 1991.
^ 1968-, Sedley, David Louis, (2005). Sublimity and skepticism in
Montaigne and Milton. Ann Arbor: University of Michigan Press.
ISBN 9780472115280. OCLC 60715259.
^ Kalupahana, David J. A History of Buddhist Philosophy: Continuities
and Discontinuities, page 21.
^ The Cowherds. Moonshadows: Conventional Truth in Buddhist
Philosophy, Oxford University Press, 2011, page 115-116.
^ Hayes, Richard P. Dignāga on the interpretation of signs, page 53.
^ Hayes, Richard P. Dignāga on the interpretation of signs, page 35.
^ Kuzminski, Adrian. Pyrrhonism: How the Ancient Greeks Reinvented
Buddhism (Studies in Comparative
Philosophy and Religion), 2008.
^ Dundas, Paul; John Hinnels ed. (2002). The Jains. London: Routledge.
ISBN 0-415-26606-8. CS1 maint: Extra text: authors list
^ a b Koller, John M. (July 2000). "
Syādvāda as the epistemological
key to the Jaina middle way metaphysics of Anekāntavāda". Philosophy
East and West. Honolulu. 50 (3): 400–7. ISSN 0031-8221.
JSTOR 1400182. Retrieved 2007-10-01.
^ Chatterjea, Tara (2001). Knowledge and Freedom in Indian Philosophy.
Lanham, MD: Lexington Books. ISBN 0739106929. pp. 77–87
^ a b Zhuangzi. The Complete works of Zhuangzi. Watson, Burton,
1925-2017. New York. ISBN 9780231164740.
^ Berthel, Ken (2015-12-01). "Language in Zhuangzi: A Theme that
Reveals the Nature of its
Relativism and Skepticism". Journal of
Chinese Philosophy. 42: 562–576. doi:10.1111/1540-6253.12215.
^ Xuerong, Ouyang (December 2003). "略论王充的怀疑主义".
JOURNAL OF KAIFENG UNIVERSITY. 17-04: 11–13 – via CNKI.
^ 1900-1995., Needham, Joseph, (1978-<1995>). The shorter
Science and civilisation in China : an abridgement of Joseph
Needham's original text. Ronan, Colin A. Cambridge: Cambridge
University Press. ISBN 9780521235822. OCLC 3345021.
Check date values in: date= (help)
^ a b Najm, Sami M. (July–October 1966). "The Place and Function of
Doubt in the Philosophies of Descartes and Al-Ghazali". Philosophy
East and West.
Philosophy East and West, Vol. 16, No. 3/4. 16 (3–4):
133–411. doi:10.2307/1397536. JSTOR 1397536.
^ Annotated translations by Richard Joseph McCarthy (Freedom and
Fulfillment, Boston: Twayne, 1980; Deliverance From Error, Louisville,
Ky.: Fons Vitae, 1999) and George F. McLean (Deliverance from error
and mystical union with the Almighty, Washington, D.C.: Council for
Research in Values and Philosophy, 2001). An earlier translation by
William Montgomery Watt
William Montgomery Watt was first published in 1953 (The faith and
practice of al-Ghazālī, London: G. Allen and Unwin).
^ Gerhard Böwering, Encyclopedia Iranica, s.v. Ghazali.
^ McCarthy 1980, p. 66
^ William James, Varieties of Religious Experience, Harvard University
Press, 1985, p. 319 [= 2002 Modern Library Paperback Edition, p. 438].
^ Lewes, George Henry (1867). The History of
Philosophy from Thales to
Comte, Vol. 2: Modern Philosophy. London: Longmans, Green, and
^ James Maffie (2005). "Aztec Philosophy". Internet Encyclopedia of
^ James Maffie, Aztec Philosophy: Understanding a World in Motion,
University Press of Colorado, 15/03/2014
Popkin, Richard H.. 2003. The History of Scepticism from Savonarola to
Bayle. New York, New York: Oxford University Press.
Popkin, Richard H. and J. R. Maia Neto, eds. 2007. Skepticism: An
Anthology. New York, New York: Prometheus Books.
Beiser, Frederick C. 1987. The Fate of Reason: German
Kant to Fichte. Cambridge, Massachusetts: Harvard University Press.
Breker, Christian. 2011. Einführender Kommentar zu Sextus Empiricus'
"Grundriss der pyrrhonischen Skepsis", Mainz, 2011: electr.
publication, University of Mainz. available online (comment on Sextus
Empiricus’ “Outlines of Pyrrhonism” in German language)
di Giovanni, George and H. S. Harris, eds. 2000. Between Kant and
Hegel: Texts in the Development of Post-Kantian Idealism. Translated
with Introductions by George di Giovanni and H. S. Harris.
Indianapolis, Indiana: Hackett Publishing.
Forster, Michael N. 1989.
Hegel and Skepticism. Cambridge,
Massachusetts: Harvard University Press.
Harris, H. S. 1985. "Skepticism, Dogmatism and Speculation in the
Critical Journal". In di Giovanni and Harris 2000.
Georg Wilhelm Friedrich Hegel. 1802. "On the Relationship of
Skepticism to Philosophy, Exposition of its Different Modifications
and Comparison of the Latest Form with the Ancient One". Translated by
H. S. Harris. In di Giovanni and Harris 2000.
Leavitt, Fred. Dancing with Absurdity: Your Most Cherished Beliefs
(and All Your Others) are Probably Wrong. (2015) Peter Lang
Thorsrud, Harald. 2009. Ancient Scepticism. Berkeley, California:
University of California Press.
Unger, Peter. 1975. Ignorance: A Case for Scepticism. Oxford, England:
Oxford University Press. 2002.
Zeller, Eduard and Oswald J. Reichel. 1892. The Stoics, Epicureans and
Sceptics. London, England: Longmans, Green, and Co.
Klein, Peter. "Skepticism". In Zalta, Edward N. Stanford Encyclopedia
Skepticism entry in the Internet Encyclopedia of
Skepticism entry in the Internet Encyclopedia of
Responses to skepticism by Keith DeRose
Skepticism and Denial by Stephen Novella MD, The New England
Journal of Skepticism
Skepticism by Peter Suber
Review and summary of
Skepticism and the Veil of Perception by Michael
Brain in a vat
Here is one hand
List of books about skepticism
List of notable skeptics
List of skeptical conferences
List of skeptical magazines
List of skeptical organizations
List of skeptical podcasts
Philosophy of psychiatry
Philosophy of perception
Space and time
Schools of thought
Acintya bheda abheda
Foundationalism / Coherentism
Internalism and Externalism
Ordinary language philosophy
Rationalism / Reasonism
Philosophy by region
Women in philosophy