The History of Skepticism

In Search of Consistency

by Renata Ziemińska (Author)
©2017 Monographs 306 Pages


This book reconstructs the history of skepticism ranging from ancient to contemporary times, from Pyrrho to Kripke. The main skeptical stances and the historical reconstruction of the concept of skepticism are connected with an analysis of their recurrent inconsistency. The author reveals that this inconsistency is not a logical contradiction but a pragmatic one. She shows that it is a contradiction between the content of the skeptical position and the implicit presumption of the act of its assertion. The thesis of global skepticism cannot be accepted as true without falling into the pragmatic inconsistency. The author explains, how skepticism was important for exposing the limits of human knowledge and inspired its development.

Table Of Contents

  • Cover
  • Title
  • Copyright
  • About the author(s)/editor(s)
  • About the book
  • This eBook can be cited
  • Table of Contents
  • Introduction
  • Chapter I. The Notion and Types of Skepticism
  • 1. Genealogy of the Term Skepticism
  • 2. Evolution of the Idea of Skepticism
  • 2.1. Ancient Skepticism: the Suspension of Judgements Aspiring to Be the Truth
  • 2.2. Medieval Skepticism: the Weakness of Human Judgements Contrasted with God’s Omnipotence
  • 2.3. Modern Skepticism: Doubting the Value of Judgements Aspiring to be Knowledge
  • 2.4. Contemporary Skepticism: Paradoxical Thesis on the Non-existence of Knowledge and Meaning
  • 3. Types of Skepticism and Related Terminology
  • Chapter II. Ancient Skepticism
  • 1. Elements of Skepticism in the Pre-Pyrrhonian Philosophy
  • 2. Pyrrho of Elis and Ethical Skepticism
  • 3. Academic Skepticism (Arcesilaus and Carneades)
  • 4. Later Pyrrhonism (Aenesidemus and Agrippa)
  • 5. Sextus Empiricus – Summa of Ancient Skepticism
  • 5.1. The Concept and the Criterion of Truth
  • 5.2. Signs and Demonstrations
  • 5.3. Physics, Ethics and the Specialized Sciences
  • 5.4. The Defense of Consistency
  • 5.5. Recent Consistency Interpretations
  • 5.6. “Throwing away the Ladder” – Does Sextus Accept Self-Refutation?
  • 5.7. Pragmatic Inconsistency of Sextan Skepticism
  • Conclusions for Ancient Skepticism
  • Chapter III. Christian Reception of Ancient Skepticism and Medieval Skepticism
  • 1. The Early Christian Thinkers about Skepticism
  • 2. St. Augustine and the Critique of Academic Skepticism
  • 3. Medieval Skeptics before William Ockham (John of Salisbury, Henry of Ghent, Peter Aureoli)
  • 4. William Ockham – Skepticism and Fideism
  • 5. Ockham’s Followers and Skepticism Based on Divine Omnipotence
  • 5.1. Nicholas of Autrecourt
  • 5.2. John of Mirecourt
  • Conclusions for Medieval Skepticism
  • Chapter IV. Modern Skepticism
  • 1. The Beginning of Modern Skepticism (Erasmus, Pico, Sanchez)
  • 2. Montaigne’s Skepticism
  • 2.1. Ancient Themes
  • 2.2. Christian Themes
  • 2.3. Renaissance Themes
  • 2.4. An Attempt to Avoid the Inconsistency Charge
  • 2.5. Montaigne’s Followers (Charron, de la Mothe le Vayer)
  • 3. Descartes’ Hypotheses and the Radicalization of Skepticism
  • 3.1. The Dream Hypothesis and the Evil Demon Hypothesis
  • 3.2. Idealism and Making Skepticism Deeper
  • 3.3. Methodic Skepticism
  • 3.4. An Attempt to Rebut Skeptical Hypotheses
  • 3.5. Skepticism between Descartes and Hume (Huet, Pascal, Bayle)
  • 4. Hume and Searching for Skepticism Consistency
  • 4.1. References to Ancient Tradition
  • 4.2. Acceptance of the Cartesian Hypotheses
  • 4.3. Broadening the Skeptical Arguments
  • 4.4. Instinct as a Rescue from Skepticism
  • 4.5. The Critique of Total Skepticism
  • 4.6. Searching for a Consistent Moderate Skepticism
  • 4.7. Dialectics of Skepticism and Naturalism
  • 5. Kant’s Transcendental Skepticism and its Continuations
  • 5.1. Kant and the Skeptical Tradition
  • 5.2. Futility of Skepticism and the Value of the Skeptical Method
  • 5.3. Transcendental Skepticism
  • 5.4. Hegel about Skepticism
  • 5.5. Nietzsche’s Skepticism
  • Conclusions for Modern Skepticism
  • Chapter V. Contemporary Skepticism
  • 1. The Problem of Skepticism and the Change of the Concept of Knowledge at the Beginning of the 20th Century
  • 1.1. Pragmatism
  • 1.2. Analytical Philosophy
  • 1.3. Phenomenology and Existentialism
  • 2. Peter Unger and Contemporary Cartesian Skepticism
  • 2.1. Knowledge as an Absolute Limit Term
  • 2.2. Hypothesis of the Evil Scientist and Brain-in-a-Vat
  • 2.3. Other Protagonists of Skepticism
  • 3. The Discussion with the Cartesian Skepticism
  • 3.1. Knowledge Does Not Require Certainty (Fallibilism)
  • 3.2. Knowledge is Not Governed by Deductive Rules (Nozick)
  • 3.3. Knowledge Does not Require Knowledge about Knowledge (Externalism)
  • 3.4. Standards for Knowledge are Changeable (Contextualism)
  • 3.5. Justification Does Not Require the Procedure of Justification (Williams)
  • 3.6. Inconsistency of Brain-in-a-Vat Hypothesis (Putnam)
  • 4. Meaning Skepticism by Kripke-Wittgenstein
  • 4.1. Thought Experiment with quus
  • 4.2. Practice as a Rescue from Skepticism
  • 4.3. Meaning Skepticism about Other Minds
  • 4.4. Skepticism about Self-Consciousness
  • Conclusions for Contemporary Skepticism
  • Conclusion: Pragmatic Inconsistency of Skepticism
  • Bibliography
  • Chronology and Geography of Skepticism
  • Index

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This book is an attempt to recreate the history of a current of thought that, for centuries, was called skepticism. It is also an attempt to present the current state of research on skepticism, focusing on the most recent interpretations of the works of ancient skeptics and contemporary positions in debates over skepticism. This book belongs to two disciplines of philosophy: the history of philosophy and epistemology. In pursuing both these lines, a historical reconstruction of the most important skeptical stances, ranging from ancient times to contemporary times, is connected with their assessment, particularly in terms of their consistency.

The skeptical stance is most easily expressed by the thesis “knowledge does not exist.” This particular thesis of global skepticism played an extremely significant role within the history of philosophy, but is also the position most likely to be attacked for a lack of internal consistency. If knowledge does not exist, how can we know, or prove this fact? Skeptics, who were not willing to keep quiet and stood by their skeptical view, were forced to search for answers to this accusation. Ancients differentiated between theory and practice, that is, between theory and situations where one could be guided by probability (Carneades), and/or appearances (Sextus Empiricus). Modern thinkers pointed to other ways of learning about the world, ways outside of intellectual investigation, such as faith (William Ockham, Michel de Montaigne) or instinct (David Hume). That was their way of searching for a possibility to continue their skeptical discourse alongside everyday life and despite the conviction of knowledge’s nonexistence. However, solutions turned out to be ineffective and accusations kept reappearing. When following the history of skepticism, one can observe that a lack of consistency seems to be its inseparable feature (Burnyeat, 1976: 65) and that a willingness to escape the aforementioned accusation was a driving force behind the creation of its later incarnations. Peter Unger, a twentieth-century skeptic, is not afraid of this lack of consistency (Unger, 1975: 6). In his opinion, this lack does not prove the falsity of skepticism. It merely reveals problems buried within human language and the thinking process.

Closer analysis of the inconsistency imbedded in skeptical stands shows that it is not simply a lack of logical consistency, or contradictions between different theses. It is rather a pragmatic inconsistency, the conflict between a proclaimed thesis and the assumptions hidden in its language formulation. This theory will be the primary outcome of this work. On the basis of the analysis of actual skeptical stands, particularly those of Sextus Empiricus and David Hume, as well the ← 9 | 10 → use of tools taken from contemporary epistemology (particularly the language-game theory of Wittgenstein and speech act theory of Searle), it is clear that pragmatic inconsistency is the best way of conceptualizing inconsistencies embedded in skepticism.

The reconstruction of the history of skepticism, with small exceptions concerning Pyrrho of Elis, will be limited to the culture of the West and focused on philosophical skepticism (religious skepticism and other varieties will appear from time to time as well). Between the many different forms of philosophical skepticism, my attention will primarily be focused on global skepticism, since this is the form that is most exposed to accusations of a lack of consistency. Other important participants in the debate (e.g. Descartes), who either deepened the argumentation of skepticism, or formulated an antiskeptical strategy, will be the object of the reconstruction alongside well-known or declared skeptics.

The following chapters, except for the first one focused on defining with precision the meaning of the term skepticism, will be devoted to the consecutive stages and epochs in the history of skepticism: ancient, medieval, modern and contemporary. The main skeptical strands of every epoch will be presented and the most important ones will undergo more meticulous analysis, with particular focus on their consistency. Concerning antiquity, Sextus Empiricus will be presented as the main representative of skepticism, principally due to the survival of his works. The Middle Ages will be represented by William Ockham, as a typical, Christian skeptic-fideist. When talking about modernity, we will turn to David Hume as a representative of the most radical and influential variety of skepticism and finally, in the context of the contemporary world, Peter Unger will be presented as the most famous self-declared, contemporary skeptic, in addition to Kripke-Wittgenstein, due to their new form of meaning skepticism.

The book makes many references to Izydora Dąmbska (1904–1983) and Richard Popkin (1923–2005). Izydora Dąmbska wrote a lot about ancient and modern skepticism and made some assertions about medieval and contemporary skepticism. Her research was my starting point and guide in the reconstruction of the history of skepticism. Richard Popkin wrote The History of Scepticism. From Savonarola to Bayle (2003). The book covers the history of modern skepticism. I continue this work extending the reconstruction of skepticism from ancient times to contemporary times, from Pyrrho to Kripke and beyond.

This book would not have been possible if it was not for the support I received at the National Science Centre which funded my research project “The History of Skepticism” (no. N N101 109137) in 2009–2012. Part of my research was presented on various occasions, including the American Philosophical Association. Pacific ← 10 | 11 → Division conference in San Diego (2012; section: Society for Skeptical Studies), the Congress of Logic, Methodology and Philosophy of Science in Nancy (2011), the Philosophical Association meeting in Lund (2012), the International Society of European Ideas conference in Nicosia (2012), workshops on ancient skepticism in Prague (2010), Philosophical Rally in Łódź (2010), conference “The Right to Believe” in Bydgoszcz (2010), two conferences of the “Przegląd Filozoficzny” [Philosophical Review] in Warsaw, devoted, respectively, to William James and David Hume (2010 and 2011) and interdisciplinary Workshops on Speech Acts in Szczecin/Pobierowo (2011). I wish to express my gratitude to all participants of these events for their comments which helped me better understand the inconsistency of skepticism. I also wish to thank the readers of the first version of this books: Maria Marcinkowska-Rosół for her comments about ancient skepticism, Agnieszka Kijewska for her comments about medieval skepticism, Ireneusz Ziemiński for his comments about modern skepticism, as well as the anonymous reviewers of the Foundation for Polish Science for their remarks about the whole book. I am thankful to Cain Elliott and Jan Pytalski for their translation of the introduction and first chapter of this book. Finally, my acknowledgments go to the Foundation for Polish Science, which provided me with a subsidy for the translation of this book, and to the University of Szczecin for financial support.

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Chapter I. The Notion and Types of Skepticism

Not simply skeptical stances, but the very term “skepticism” has undergone considerable evolution. Nevertheless, it would be hard to conduct the aforementioned reconstruction without using skepticism as understood in a contemporary manner. As already indicated, I will assume that the word skepticism stands for a thesis claiming that knowledge does not exist. I will treat this contemporary thesis as a model of skepticism in comparison with less typical theses or those positions that do not propose any thesis whatsoever.

1. Genealogy of the Term Skepticism

Skepticism was not always named this way and the representatives of such schools were not always called skeptics. Along with their critics, the skeptics of previous ages did not use the term skeptikoi (σκεπτικοί, skeptics) to name thinkers from the schools of skepticism, even though the Greek verb skeptomai, the noun skepsis and the adjective skeptikos already existed. The verb skeptomai, meaning “I look,” “I research” can be spotted already in the works of Homer. Many writers, including Thucydides, Hippocrates, Sophocles, Plato (Laches 185b) and Aristotle (EN 1103b), use the verb regularly. The noun skepsis, meaning “a look,” “research” can be found in the works of Plato (Phaedo 83a, Theaetetus 201a) and Aristotle (Physics 228, EN 1159b). All of this usage comes from the pre-skeptic period. However, in the times of Pyrrho and the academic skeptics, the situation was similar. Pyrrho’s student, Timon of Phlius, uses the word skeptosyne in his poem Silloi, but it carries its common, vernacular meaning “research” (Bett 2010d: 5). The adjective skeptikos used at that time did not refer to the representatives of the skeptical school of thought, but meant “curious” or “inquiring.” This is the case with an epicurean Philodemus (Rhet. 1.191) from the 1st century BC, Plutarch (Moralia 990A), and sometimes Philo of Alexandria from the 1st century A. D. (De Ebrietate 202). In the works by Philo of Alexandria, skeptikos is used for the first time, as far as we know, as the name for neo-Pyrrhonists (Congr. 52, see Bett 2003: 148). In the 2nd century, the adjectival noun skeptikoi, referring to the school of philosophical thought, appears in many different sources: the works by a sophist Lucian of Samosata (Vit. Auct. 27.40), a Roman writer Aulus Gellius (NA 11.5) and a little later in the writings of Sextus Empiricus (PH 1.3–1.21). In the 3rd century, in the works of Diogenes Laertius (DL 9.70), it is already a well-established, technical ← 13 | 14 → term. Sextus will also use the noun skepsis as name for the branch of philosophy (PH 1.5, 1.7).

The word skeptikoi, or its Latin equivalent, are nowhere to be found in the oldest preserved, direct sources on the Greek skeptics, which are the works of Cicero from the 1st century BC. He did not write about “skeptics” but about “academics” who, for him, were the supporters of epochē, or the suspension of all judgement. Plutarch called academics “men, who suspend their judgement of everything” (Adversus Colotem 1121E=LS 68H1). Epochē was, for Cicero, a fundamental characteristic of academic skepticism. He mentioned Pyrrho as a moralist, famous for his indifference, but not a supporter of epochē (contrary to what Aristocles, Sextus Empiricus or Diogenes Laertius later wrote about him). The absence of the word epochē in the works of Pyrrho could be a possible excuse for Cicero (however, sources reveal the presence of a similar word – aphasia – which means “not making judgements”). Regardless of the right answer to this mystery, neither the writings of Pyrrho or Cicero use the term skeptikoi as a name for a philosophical school. We can presume that the term was coined in the neo-Pyrrhonian school of Aenesidemus and that it was Philo of Alexandria, who has conveyed the findings of Aenesidemus to us and provided the very first example of such usage.

At the beginning of the 2nd century, the word skeptikoi was clearly used to designate Pyrrho’s followers, as well as academics. It might have played the role of a unifier for these two skeptical currents of thought. This was the goal of Phavorinus, a student of Plutarch (according to Philostratus, Lives of the Sophists 1.8.6). He was an admirer of Pyrrho and combined academic skepticism with neo-Pyrrhonism. Aulus Gellius, a citizen of Rome, was Phavorinus’ student. Composed in Latin, his writings from the 2nd century include the Greek word skeptikoi as name of the school. In Noctes Atticae, Aulius Gellius questions the difference between the academics and Pyrrhonists (he refers to this question as an old problem, debated by many Greek authors) and, collectively, calls them skeptikoi (skeptics – those who look and examine, but do not find a solution). He mentions other names as well: ephektikoi (ephectics – those who suspend judgement) and aporetikoi (aphorectics – those who are helpless when confronted with a problem).1 Sextus Empiricus and Diogenes Laertius will likewise write about this later on. Sextus will add a specific name to the three mentioned before – Pyrrhonists (PH 1.7) – and Diogenes (DL 9.70) will contribute with ← 14 | 15 → his zetetikoi (zetetics – those who search, but never find). The first and the last names are hard to distinguish, but we can assume that the first refers to a lack of understanding, despite analyzing and drawing conclusions, while the last one refers to the lack of an answer, despite searching and inquiring. These four names, with the exception of the one specific name (Pyrrhonists), grasp the important features of the skeptical attitude: a lack of results after search and examination, and a suspension of all judgement and observing problems without solution. All these names were used during the first centuries of our era (Floridi 2002: 104–5). The name ephectics, used by Clement of Alexandria (Strom. 8.8.15) and neo-Platonists from the 6th century (Ammonius, Simplicius, Olympiodoros; compare Floridi 2002: 20) had a decent range, but “Pyrrhonists” and “skeptics” ultimately dominated the others. One should add that during the Middle Ages, under the influence of St. Augustine and Cicero, “skeptics” were called “academics.”

In the time of the neo-Pyrrhonian school’s activity (Aenesidemus, Agrippa, Sextus Empiricus), under the patronage of Pyrrho, its representatives were called “Pyrrhonists” (compare Photius’ Bibliotheca, 169b). However, the word “skeptic” was increasingly popular over time (Floridi 2002: 103). It seems that the main role in this process of establishing terminology was played by Sextus Empiricus, who wrote about skeptics and skepticism (PH 1.1–30) and whose works became the main source of information on skepticism for modern Europe. On the one hand, Sextus was not friendly toward academics (and especially towards Carneades), depriving them of the right to call themselves “skeptics” (instead calling them “negative dogmatics”). On the other hand, he assumed a certain distance when writing about Pyrrho, who was known as the originator of skepticism, but whose exact ideas were not that well known to Sextus (PH 1.7). Most likely written in accordance with the tradition of the neo-Pyrrhonian school, his Outlines of Skepticism (or Pyrrhonism) hardly ever names the representatives of that school “Pyrrhonists” (PH 1.7,11,13) and more often calls them “skeptics” (skeptikoi). Also, in the Lives and Opinions of Diogenes, it is a term used more often than “Pyrrhonists” (DL 9.11). Diogenes writes about the problems resulting from the usage of the term “Pyrrhonism” as caused by the lack of a doctrine in the teachings of Pyrrho (one can become a Pyrrhonist only through mimicking Pyrrho’s style of life). At the beginning of Outlines, Sextus divides philosophers between dogmatics, who claim that they have found the truth (e.g. Aristotle), academics, who claim that the truth is impossible to attain (e.g. Carneades) and skeptics, who still search for the truth (PH 1.1–4). This famous division of philosophical stands, cited by Montaigne and repeated by his followers, confirms the key role of the term “skepticism in the history of doubting philosophers. The broad definition of skepticism from ← 15 | 16 → the beginning of Sextus’ Outlines is defined more precisely later in the work with the introduction of the principle of the suspension of judgement.

The choice made by Sextus likewise became the choice of modern philosophy. In the 9th century, Photius also assumed that Pyrrhonists are some kind of skeptics (Bibliotheca 169b). In 1430, when Traversari’s Latin translation of Diogenes’s Lives and Opinions appeared and began to circulate, the Latin word scepticus entered the dictionary of modernity (Popkin 2003: 17, Hankinson 1995: 10, Floridi 2002: 14). In medieval Latin, the word scepticus did not exist. It was transliterated from the Greek skeptikos as a technical term, and so the literal translation – “researcher or explorer” – could be misleading. The Latin term scepticus appeared in the 2nd century in Attic Nights by Aulus Gellius and, similarly to the terms we find in the works of Cicero, it could have been a template for Renaissance translators. In 1562, the printed Latin translation of Sextus’ Outlines of Pyrrhonism by Stephanus appeared. Only then did the word scepticus become truly popular in Latin Europe (Popkin 2003: 18, Hankinson 1995: 11, Floridi 2010: 281). The publication of Montaigne’s Essays (1580) introduced the French term sceptique and further popularized the notion of skepticism.

Thanks to the title of Sextus Empiricus’ work, Outlines of Pyrrhonism, and a chapter devoted to Pyrrho in Diogenes Laertius’s Lives and Opinions, the term Pyrrhonism did not disappear. It was moderately popular in the modern epoch and used by Montaigne in his Essays and by Hume in his Treatise and An Enquiry. At present, it operates in the background and is used by specialists researching different varieties of ancient skepticism (Pyrrhonism is a current of thought ascribed to Pyrrho, Aenesidemus, Agrippa, and Sextus Empiricus, while “academic skepticism” is connected to Arcesialus, Carneades and other members of the Academia). The word “skepticism,” in its different linguistic variations, became a term that denoted both academicism and Pyrrhonism, alongside other positions questioning the existence of human knowledge.

2. Evolution of the Idea of Skepticism

2.1. Ancient Skepticism: the Suspension of Judgements Aspiring to Be the Truth

We differentiate between two types of skepticism in ancient times: Pyrrhonism and academic skepticism. The first was radical, while the second was moderate. In both cases, the skeptical attitude involved epochē – the suspension of all judgement. Epochē is not a theoretical posture, but an attitude toward life that is recommended in order to avoid suffering and achieve happiness. It entailed life without making judgements of any kind or a life without any beliefs. ← 16 | 17 →

Sextus Empiricus passed on the radical version of skepticism. The arguments which he presents in his works suggest that there is no way to rationally prefer any given judgement, prior to its negation. Observational phenomena are dependent on circumstances and every attempt to justify any given thesis leads to an infinite regress or results in circular reasoning. For the same reason, it is impossible to establish a criterion of truth, or present a valid proof. Since no belief can be guaranteed as true, Pyrrhonists simply recommended a life without belief. Sextus states that such life is possible and explains that it consists of the passive acceptance of sensations and following customs and stereotypes imbedded in us by society.

Academic skepticism was decidedly more moderate. In this context, epochē is concerned with theory and not practice. There are no criteria for truth and all judgements are doubtful, but there still exists a need to be guided in one’s everyday actions. Guidance through persuasive appearances seems sufficient. Carneades suspends all judgement, but in practice he approves of what is subjectively probable (pithanon). Academics, while attempting to solve the conflict between skepticism’s assumptions and requirements of everyday life, discovered the so-called weak assent (an acceptance of what is not certain but probable or persuasive). Pyrrhonists, or at least Sextus and Aenesidemus, considered the approval of uncertain appearances to be a betrayal of skepticism.


ISBN (Hardcover)
Publication date
2017 (April)
History of ideas Theories of knowledge Consistency of skepticism Evolution of the concept of skepticism Knowledge production Fallibilism
Frankfurt am Main, Bern, Bruxelles, New York, Oxford, Warszawa, Wien, 2017. 306 pp.

Biographical notes

Renata Ziemińska (Author)

Renata Ziemińska is professor of philosophy and chair in epistemology at the University of Szczecin, Poland. She is member of The Committee on Philosophical Sciences of the Polish Academy of Sciences, member of Society for Skeptical Studies and International Society for the Study of Skepticism.


Title: The History of Skepticism
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