Philosophical skepticism


Philosophical skepticism is a family of philosophical views that question the possibility of knowledge. It differs from other forms of skepticism in that it even rejects very plausible knowledge claims that belong to basic common sense. Philosophical skeptics are often classified into two general categories: Those who deny all possibility of knowledge, and those who advocate for the suspension of judgment due to the inadequacy of evidence. This distinction is modeled after the differences between the Academic skeptics and the Pyrrhonian skeptics in ancient Greek philosophy. Pyrrhonian skepticism is a practice of suspending judgement, and skepticism in this sense is understood as a way of life that helps the practitioner achieve inner peace. Some types of philosophical skepticism reject all forms of knowledge while others limit this rejection to certain fields, for example, knowledge about moral doctrines or about the external world. Some theorists criticize philosophical skepticism based on the claim that it is a self-refuting idea since its proponents seem to claim to know that there is no knowledge. Other objections focus on its implausibility and distance from regular life.

Overview

Philosophical skepticism is a doubtful attitude toward commonly accepted knowledge claims. Skepticism in general is a questioning attitude toward all kinds of knowledge claims. In this wide sense, it is quite common in everyday life: many people are ordinary skeptics about parapsychology or about astrology because they doubt the claims made by proponents of these fields. But the same people are not skeptical about other knowledge claims like the ones found in regular school books. Philosophical skepticism differs from ordinary skepticism in that it even rejects knowledge claims that belong to basic common sense and seem to be very certain. For this reason, it is sometimes referred to as radical doubt. In some cases, it is even proclaimed that one does not know that "I have two hands" or that "the sun will come out tomorrow". In this regard, philosophical skepticism is not a position commonly adopted by regular people in everyday life. This denial of knowledge is usually associated with the demand that one should suspend one's beliefs about the doubted proposition. This means that one should neither believe nor disbelieve it but keep an open mind without committing oneself one way or the other. Philosophical skepticism is often based on the idea that no matter how certain one is about a given belief, one could still be wrong about it. From this observation, it is argued that the belief does not amount to knowledge. Philosophical skepticism follows from the consideration that this might be the case for most or all beliefs. Because of its wide-ranging consequences, it is of central interest to theories of knowledge since it questions their very foundations.
According to some definitions, philosophical skepticism is not just the rejection of some forms of commonly accepted knowledge but the rejection of all forms of knowledge. In this regard, we may have relatively secure beliefs in some cases but these beliefs never amount to knowledge. Weaker forms of philosophical skepticism restrict this rejection to specific fields, like the external world or moral doctrines. In some cases, knowledge per se is not rejected but it is still denied that one can ever be absolutely certain.
There are only few defenders of philosophical skepticism in the strong sense. In this regard, it is much more commonly used as a theoretical tool to test theories. On this view, it is a philosophical methodology that can be utilized to probe a theory to find its weak points, either to expose it or to modify it in order to arrive at a better version of it. However, some theorists distinguish philosophical skepticism 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 claims. Similarly, scientific skepticism differs from philosophical skepticism in that scientific skepticism is an epistemological position in which one questions the veracity of claims lacking empirical evidence. In practice, the term most commonly references the examination of claims and theories that appear to be pseudoscience, rather than the routine discussions and challenges among scientists.
In ancient philosophy, skepticism was seen not just as a theory about the existence of knowledge but as a way of life. This outlook is motivated by the idea that suspending one's judgment on all kinds of issues brings with it inner peace and thereby contributes to the skeptic's happiness.

Classification

Skepticism can be classified according to its scope. Local skepticism involves being skeptical about particular areas of knowledge, whereas radical skepticism claims that one cannot know anything—including that one cannot know about knowing anything.
Skepticism can also be classified according to its method. Western philosophy has 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 justification rather than the possibility of doubt. According to this view, none of the ways in which one might attempt to justify a claim are adequate. One can justify a claim based on other claims, but this leads to an infinite regress of justifications. One can use a dogmatic assertion, but this is not a justification. One can use circular reasoning, but this fails to justify the conclusion.

Skeptical scenarios

A skeptical scenario is a hypothetical situation which can be used in an argument for skepticism about a particular claim or class of claims. Usually the scenario posits the existence of a deceptive power that deceives our senses and undermines the justification of knowledge otherwise accepted as justified, and is proposed in order to call into question our ordinary claims to knowledge on the grounds that we cannot exclude the possibility of skeptical scenarios being true. Skeptical scenarios have received a great deal of attention in modern Western philosophy.
The first major skeptical scenario 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 deceive me."
  • The "evil demon problem", also known as "Descartes' evil demon", was first proposed by René Descartes. It invokes the possibility of a being who could deliberately mislead one into falsely believing everything that you take to be true.
  • The "brain in a vat" hypothesis is cast in contemporary 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. Further, it asserts that since a brain in a vat would have no way of knowing that it was a brain in a vat, you cannot prove that you are not a brain in a vat.
  • The "dream argument", proposed by both René Descartes and Zhuangzi, supposes reality to be indistinguishable from a dream.
  • The "five minute hypothesis", most notably proposed by Bertrand Russell, suggests that we cannot prove that the world was not created five minutes ago.
  • The "simulated reality hypothesis" or "Matrix hypothesis" suggests that everyone, or even the entire universe, might be inside a computer simulation or virtual reality.
  • The "Solipsistic" theory that claims that knowledge of the world is an illusion of the Self.

    Epistemological skepticism

Skepticism, as an epistemological view, calls into question whether knowledge is possible at all. This is distinct from other known skeptical practices, including Cartesian skepticism, as it targets knowledge in general instead of individual types of knowledge.
Skeptics argue that belief in something does not justify an assertion of knowledge of it. In this, skeptics oppose foundationalism, which states that there are basic positions that are self-justified or beyond justification, without reference to others.
Among other arguments, skeptics use the Münchhausen trilemma and the problem of the criterion to claim that no certain belief can be achieved. This position is known as "global skepticism" or "radical skepticism." Foundationalists have used the same trilemma as a justification for demanding the validity of basic beliefs. Epistemological nihilism rejects the possibility of human knowledge, but not necessarily knowledge in general.
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. Some mitigated skeptics are also fallibilists, arguing that knowledge does not require certainty. Mitigated skeptics hold that knowledge does not require certainty and that many beliefs are, in practice, certain to the point that they can be safely acted upon in order to live significant and meaningful lives. 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 knowledge. Unmitigated skeptics believe that objective truths are unknowable and that man should live in an isolated environment in order to win mental peace. This is because everything, according to them, is changing and relative. The refusal to make judgments is of uttermost importance since there is no knowledge; only probable opinions.