Alphabetical Table of Contents



1 Basic Tools for Argument

1.1 Arguments, premises and conclusions

1.2 Deduction

1.3 Induction

1.4 Validity and soundness

1.5 Invalidity

1.6 Consistency

1.7 Fallacies

1.8 Refutation

1.9 Axioms

1.10 Definitions

1.11 Certainty and probability

1.12 Tautologies, self-contradictions and the law of non-contradiction

2 More Advanced Tools

2.1 Abduction

2.2 Hypothetico-deductive method

2.3 Dialectic

2.4 Analogies

2.5 Anomalies and exceptions that prove the rule

2.6 Intuition pumps

2.7 Logical constructions

2.8 Reduction

2.9 Thought experiments

2.10 Useful fictions

3 Tools for Assessment

3.1 Alternative explanations

3.2 Ambiguity

3.3 Bivalence and the excluded middle

3.4 Category mistakes

3.5 Ceteris paribus

3.6 Circularity

3.7 Conceptual incoherence

3.8 Counterexamples

3.9 Criteria

3.10 Error theory

3.11 False dichotomy

3.12 False cause

3.13 Genetic fallacy

3.14 Horned dilemmas

3.15 Is/ought gap

3.16 Masked man fallacy

3.17 Partners in guilt

3.18 Principle of charity

3.19 Question-begging

3.20 Reductios

3.21 Redundancy

3.22 Regresses

3.23 Saving the phenomena

3.24 Self-defeating arguments

3.25 Sufficient reason

3.26 Testability

4 Tools for Conceptual Distinctions

4.1 A priori/a posteriori

4.2 Absolute/relative

4.3 Analytic/synthetic

4.4 Categorical/modal

4.5 Conditional/biconditional

4.6 De re/de dictoDefeasible/indefeasible

4.7 Entailment/implication

4.8 Essence/accident

4.9 Internalism/externalism

4.10 Knowledge by acquaintance/description

4.11 Necessary/contingent

4.12 Necessary/sufficient

4.13 Objective/subjective

4.14 Realist/non-realist

4.15 Sense/reference

4.16 Syntax/semantics

4.17 Thick/thin concepts

4.18 Types/tokens

5 Tools of Historical Schools and Philosophers

5.1 Aphorism, fragment, remark

5.2 Categories and specific differences

5.3 Elenchus and aporia

5.4 Hume’s fork

5.5 Indirect discourse

5.6 Leibniz’s law of identity

5.7 Ockham’s razor

5.8 Phenomenological method(s)

5.9 Signs and signifiers

5.10 Transcendental argument

6 Tools for Radical Critique

6.1 Class critique

6.2 Deconstruction and the critique of presence

6.3 Empiricist critique of metaphysics

6.4 Feminist critique

6.5 Foucaultian critique of power

6.6 Heideggerian critique of metaphysics

6.7 Lacanian critique

6.8 Critiques of naturalism

6.9 Nietzschean critique of Christian-Platonic culture

6.10 Pragmatist critique

6.11 Sartrean critique of ‘bad faith’

7 Tools at the Limit

7.1 Basic beliefs

7.2 Godel and incompleteness

7.3 Philosophy and/as art

7.4 Mystical experience and revelation

7.5 Paradoxes

7.6 Possibility and impossibility

7.7 Primitives

7.8 Self-evident truths

7.9 Scepticism

7.10 Underdetermination

Internet Resources for Philosophers


Julian Baggini is editor and co-founder of The Philosophers’ Magazine ( He is the author of several books, including The Ethics Toolkit (with Peter S. Fosl, Wiley-Blackwell, 2007), Welcome to Everytown: A Journey into the English Mind (2008), Complaint (2008) and Should You Judge This Book by Its Cover? (2009). He has written for numerous newspapers and magazines, including the Guardian, the Financial Times, Prospect and the New Statesman, as well as for the think tanks the Institute of Public Policy Research and Demos.

Peter S. Fosl is Professor of Philosophy at Transylvania University in Lexington, Kentucky. He is co-author with Julian Baggini of The Ethics Toolkit (Wiley-Blackwell, 2007) and is also co-editor of the Dictionary of Literary Biography (2002) volumes on British philosophy, as well as coeditor with David E. Cooper of Philosophy: The Classic Readings (Wiley-Blackwell, 2009). Fosl’s scholarly publications address topics in scepticism, ethics, the philosophy of religion and the history of philosophy.

Praise for the first edition

‘The Philosopher’s Toolkit provides a welcome and useful addition to the introductory philosophy books available. It takes the beginner through most of the core conceptual tools and distinctions used by philosophers, explaining them simply and with abundant examples. Newcomers to philosophy will find much in here that will help them to understand the subject.’

David S. Oderberg,
University of Reading

‘... the average person who is interested in arguments and logic but who doesn’t have much background in philosophy would certainly find this book useful, as would anyone teaching a course on arguments, logic, and reasoning. Even introductory courses on philosophy in general might benefit because the book lays out so many of the conceptual “tools” which will prove necessary over students’ careers.’

‘Its choice of tools for basic argument ... is sound, while further tools for argument ... move through topics and examples concisely and wittily ... Sources are well chosen and indicated step by step. Sections are cross-referenced (making it better than the Teach Yourself “100 philosophical concepts”) and supported by a useful index.’

Reference Reviews


For Rick O’Neil, colleague and friend, in memoriam

Alphabetical Table of Contents

4.1    Apriori/a posteriori

2.1   Abduction

4.2   Absolute/relative

3.1   Alternative explanations

3.2   Ambiguity

2.4   Analogies

4.3   Analytic/synthetic

2.5   Anomalies and exceptions that prove the rule

5.1   Aphorism, fragment, remark

1.1   Arguments, premises and conclusions

1.9   Axioms

7.1   Basic beliefs

3.3   Bivalence and the excluded middle

4.4   Categorical/modal

5.2   Categories and specific differences

3.4   Category mistakes

1.11   Certainty and probability

3.5    Ceteris paribus

3.6   Circularity

6.1   Class critique

3.7   Conceptual incoherence

4.5   Conditional/biconditional

1.6   Consistency

3.8   Counterexamples

3.9   Criteria

6.8   Critiques of naturalism

6.2   Deconstruction and the critique of presence

1.2   Deduction

4.7   Defeasible/indefeasible

1.10   Definitions

4.6    De re/de dicto

2.3   Dialectic

5.3    Elenchus and aporia

6.3   Empiricist critique of metaphysics

4.8   Entailment/implication

3.10   Error theory

4.9   Essence/accident

1.7   Fallacies

3.12   False cause

3.11   False dichotomy

6.4   Feminist critique

6.5   Foucaultian critique of power

3.13   Genetic fallacy

7.2   Gödel and incompleteness

6.6   Heideggerian critique of metaphysics

3.14   Horned dilemmas

5.4   Hume’s fork

2.2   Hypothetico-deductive method

5.5   Indirect discourse

1.3   Induction

4.10   Internalism/externalism

2.6   Intuition pumps

1.5   Invalidity

3.15   Is/ought gap

4.11   Knowledge by acquaintance/description

6.7   Lacanian critique

5.6   Leibniz’s law of identity

2.7   Logical constructions

3.16   Masked man fallacy

7.4   Mystical experience and revelation

4.12   Necessary/contingent

4.13   Necessary/sufficient

6.9   Nietzschean critique of Christian-Platonic culture

4.14   Objective/subjective

5.7   Ockham’s razor

7.5   Paradoxes

3.17   Partners in guilt

5.8   Phenomenological method(s)

7.3   Philosophy and/as art

7.6   Possibility and impossibility

6.10   Pragmatist critique

7.7   Primitives

3.17   Principle of charity

3.18   Question-begging

4.15   Realist/non-realist

2.8   Reduction

3.19   Reductios

3.20   Redundancy

1.8   Refutation

3.21   Regresses

6.11   Sartrean critique of ‘bad faith’

3.22   Saving the phenomena

7.9   Scepticism

3.23   Self-defeating arguments

7.8   Self-evident truths

4.16   Sense/reference

5.9   Signs and signifiers

3.24   Sufficient reason

4.17   Syntax/semantics

1.12   Tautologies, self-contradictions and the law of non-contradiction

3.25   Testability

4.18   Thick/thin concepts

2.9   Thought experiments

5.10   Transcendental argument

4.19   Types/tokens

7.10   Underdetermination

2.10   Useful fictions

1.4   Validity and soundness


Philosophy can be an extremely technical and complex affair, one whose terminology and procedures are often intimidating to the beginner and demanding even for the professional. Like that of surgery, the art of philosophy requires mastering a body of knowledge, but it also requires acquiring precision and skill with a set of instruments or tools. The Philosopher’s Toolkit may be thought of as a collection of just such tools. Unlike those of a surgeon or a master woodworker, however, the instruments presented by this text are conceptual – tools that can be used to analyse, manipulate and evaluate philosophical concepts, arguments and theories.

The Toolkit can be used in a variety of ways. It can be read cover to cover by those looking for instruction on the essentials of philosophical reflection. It can be used as a course book on basic philosophical method or critical thinking. It can also be used as a reference book to which general readers and more advanced philosophers can turn in order to find quick and clear accounts of the key concepts and methods of philosophy. The aim of the book, in other words, is to act as a conceptual toolbox from which all those from neophytes to master artisans can draw instruments that would otherwise be distributed over a diverse set of texts and require long periods of study to acquire.

For this second edition, we have expanded the book from six to seven sections, and reviewed and revised every single entry. These sections progress from the basic tools of argumentation to sophisticated philosophical concepts and principles. The text passes through instruments for assessing arguments to essential laws, principles and conceptual distinctions. It concludes with a discussion of the limits of philosophical thinking.

Each of the seven sections contains a number of compact entries comprising an explanation of the tool it addresses, examples of the tool in use and guidance about the tool’s scope and limits. Each entry is cross-referenced to other related entries. Suggestions for further reading are included, and those particularly suitable for novices are marked with an asterisk. There is also a list of Internet resources at the back of the book.

Becoming a master sculptor requires more than the ability to pick up and use the tools of the trade: it requires flair, talent, imagination and practice. In the same way, learning how to use these philosophical tools will not turn you into a master of the art of philosophy overnight. What it will do is equip you with many skills and techniques that will help you philosophize better.


We are indebted to Nicholas Fearn, who helped to conceive and plan this book, and whose fingerprints can still be found here and there. We are deeply grateful to Jeff Dean at Wiley-Blackwell for nurturing the book from a good idea in theory to, we hope, a good book in practice. Thanks to Rick O’Neil, Jack Furlong, Ellen Cox, Mark Moorman, Randall Auxier, Bradley Monton and Tom Flynn for their help with various entries as well as to the anonymous reviewers for their thorough scrutiny of the text. We are also thankful for the work of Peter’s secretary Ann Cranfill as well as of many of his colleagues for proofreading. Robert E. Rosenberg, Peter’s colleague in chemistry, exhibited extraordinary generosity in reviewing the scientific content of the text. We would also like to thank Graeme Leonard and Eldo Barkhuizen for their careful and remarkably thorough editorial work. Thanks also to Peter’s spouse and children – Catherine Fosl, Isaac Fosl-van Wyke and Elijah Fosl – and to Julian’s partner, Antonia, for their patient support.