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- Herausgeber: John Wiley & Sons
- Kategorie: Geisteswissenschaft
- Sprache: Englisch
A new edition of the bestselling guide to the study of philosophy: the ideal intellectual ‘toolkit’ for sharpening analytical skills and building philosophical acuity
Whether used as a guide to basic principles or a resource for key concepts and methods, The Philosopher's Toolkit equips readers with all the intellectual ‘tools’ necessary for engaging closely with philosophical argument and developing fluency in the methods and language of philosophical inquiry. Featuring accessible explanations, practical examples, and expert guidance, this text empowers readers to understand traditional philosophical thinking and to engage with new ideas.
- Focuses on the practical methods and concepts necessary for philosophical inquiry
- Presents a versatile resource for both novice and advanced students in areas of philosophy, critical theory, and rhetoric
- Adopts a pluralistic approach to teaching philosophy, making this a suitable resource for many courses
- Delivers extensive cross-referenced entries, recommended readings, and updated online resources
- Covers an array of topics, from basic tools of argumentation to sophisticated philosophical principles
- Fully revised and updated to include new topics and entries as well as expanded recommended reading lists to encourage further study
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Veröffentlichungsjahr: 2020
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Table of Contents
Cover
Acknowledgements
Alphabetical Table of Contents
Preface
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 Performativity and speech acts
2.9 Reduction
2.10 Representation
2.11 Thought experiments
2.12 Useful fictions
3 Tools for Assessment
3.1 Affirming, denying, and conditionals
3.2 Alternative explanations
3.3 Ambiguity and vagueness
3.4 Bivalence and the excluded middle
3.5 Category mistakes
3.6
Ceteris paribus
3.7 Circularity
3.8 Composition and division
3.9 Conceptual incoherence
3.10 Contradiction/contrariety
3.11 Conversion, contraposition, obversion
3.12 Counterexamples
3.13 Criteria
3.14 Doxa/para‐doxa
3.15 Error theory
3.16 False dichotomy
3.17 False cause
3.18 Genetic fallacy
3.19 Horned dilemmas
3.20 Is/ought gap
3.21 Masked man fallacy
3.22 Partners in guilt
3.23 Principle of charity
3.24 Question‐begging
3.25 Reductios
3.26 Redundancy
3.27 Regresses
3.28 Saving the phenomena
3.29 Self‐defeating arguments
3.30 Sufficient reason
3.31 Testability
4 Tools for Conceptual Distinctions
4.1 A
priori/a posteriori
4.2 Absolute/relative
4.3 Analytic/synthetic
4.4 Belief/knowledge
4.5 Categorical/modal
4.6 Cause/reason
4.7 Conditional/biconditional
4.8
De re/de dicto
4.9 Defeasible/indefeasible
4.10 Entailment/implication
4.11 Endurantism/perdurantism
4.12 Essence/accident
4.13 Internalism/externalism
4.14 Knowledge by acquaintance/description
4.15 Mind/body
4.16 Necessary/contingent
4.17 Necessary/sufficient
4.18 Nothingness/being
4.19 Objective/subjective
4.20 Realist/non‐realist
4.21 Sense/reference
4.22 Substratum/bundle
4.23 Syntax/semantics
4.24 Universal/particular
4.25 Thick/thin concepts
4.26 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 Hegel’s master/slave dialectic
5.5 Hume’s fork
5.6 Indirect discourse
5.7 Leibniz’s law of identity
5.8 Ockham’s razor
5.9 Phenomenological method(s)
5.10 Signs and signifiers
5.11 Transcendental argument
6 Tools for Radical Critique
6.1 Class critique
6.2
Différance,
deconstruction, and the critique of presence
6.3 Empiricist critique of metaphysics
6.4 Feminist and gender critiques
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 Gödel and incompleteness
7.3 Hermeneutic circle
7.4 Philosophy and/as art
7.5 Mystical experience and revelation
7.6 Paradoxes
7.7 Possibility and impossibility
7.8 Primitives
7.9 Self‐evident truths
7.10 Scepticism
7.11 Underdetermination and incommensurability
Index
End User License Agreement
Guide
Cover
Table of Contents
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Peter S. Fosl is Professor of Philosophy and Chair of PPE at Transylvania University, Kentucky. He is author of Hume’s Scepticism (2020), co‐author of The Critical Thinking Toolkit (Wiley Blackwell, 2016) and The Ethics Toolkit (Wiley Blackwell, 2007), editor of The Big Lebowski and Philosophy (Wiley Blackwell, 2012), and co‐editor of Philosophy: The Classic Readings (Wiley Blackwell, 2009).
Julian Baggini is Academic Director of the Royal Institute of Philosophy and an Honorary Research Fellow at the University of Kent. He was the founding editor of The Philosophers’ Magazine and has written for numerous newspapers and magazines, as well as for the think tanks The Institute of Public Policy Research, Demos, and Counterpoint. He is the author, co‐author, or editor of over 20 books, including How the World Thinks, The Virtues of the Table, The Ego Trick, Freedom Regained, and The Edge of Reason.
Praise for previous editions
‘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.’
About.com
‘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
“This book is . . . an encyclopedia of philosophy. It should be of great use as a quick and accurate reference guide to the skill of philosophy, especially for beginners, but also for instructors . . . highly recommended.”
Choice
“The Philosopher’s Toolkit is a very good book. It could be highly useful for both introductory courses in philosophy, or philosophical methodology, as well as independent study for anyone interested in the methods of argument, assessment and criticism . . . It is unique in approach, and written in a pleasant and considerate tone. This book will help one to get going to do philosophy, but more advanced students might find this text helpful too. I wish I had had access to this book as an undergraduate.”
Teaching Philosophy
PETER S. FOSL and JULIAN BAGGINI
THE PHILOSOPHER’S
A Compendium of PhilosophicalConcepts and Methods
THIRD EDITION
This third edition first published 2020© 2020 Peter S. Fosl and Julian Baggini
Edition history: Blackwell Publishing Ltd (1e, 2003; 2e, 2010)
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.
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Library of Congress Cataloging‐in‐Publication Data
Names: Fosl, Peter S., author. | Baggini, Julian, author.Title: The philosopher’s toolkit : a compendium of philosophical concepts and methods / Peter S. Fosl and Julian Baggini.Description: Third edition. | Hoboken : Wiley‐Blackwell, 2020. | Includes bibliographical references and index.Identifiers: LCCN 2019053537 (print) | LCCN 2019053538 (ebook) | ISBN 9781119103219 (paperback) | ISBN 9781119103226 (adobe pdf) | ISBN 9781119103233 (epub)Subjects: LCSH: Reasoning. | Methodology.Classification: LCC BC177 .F675 2020 (print) | LCC BC177 (ebook) | DDC 101–dc23 LC record available at https://lccn.loc.gov/2019053537LC ebook record available at https://lccn.loc.gov/2019053538
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For Rick O’Neil, colleague and friend, in memoriam
Acknowledgements
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, Avery Kolers, Tom Flynn, and Saul Kutnicki 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 express our appreciation to Manish Luthra, Marissa Koors, Liz Wingett, Daniel Finch, Rachel Greenberg, Aneetta Antony, and Caroline McPherson at Wiley for their careful and supportive editorial work. Thanks also to Peter’s students for their feedback, as well as for corrections and suggestions for improvement sent to us from several readers. Our enduring gratitude goes to Peter’s spouse and children – Catherine Fosl, Isaac Fosl‐van Wyke, and Elijah Fosl – as well as to Julian’s partner, Antonia, for their patient support.
Alphabetical Table of Contents
3.1
Affirming, denying, and conditionals
4.1
A priori
/
a posteriori
2.1
Abduction
4.2
Absolute/relative
3.2
Alternative explanations
3.3
Ambiguity and vagueness
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
4.4
Belief/knowledge
3.4
Bivalence and the excluded middle
4.5
Categorical/modal
5.2
Categories and specific differences
3.5
Category mistakes
4.6
Cause/reason
1.11
Certainty and probability
3.6
Ceteris paribus
3.7
Circularity
6.1
Class critique
3.8
Composition and division
3.9
Conceptual incoherence
4.7
Conditional/biconditional
1.6
Consistency
3.10
Contradiction/contrariety
3.11
Conversion, contraposition, obversion
3.12
Counterexamples
3.13
Criteria
6.8
Critiques of naturalism
6.2
Différance,
deconstruction, and the critique of presence
1.2
Deduction
4.9
Defeasible/indefeasible
1.10
Definitions
4.8
De re/de dicto
2.3
Dialectic
3.14
Doxa/para‐doxa
5.3
Elenchus
and
aporia
6.3
Empiricist critique of metaphysics
4.11
Endurantism/perdurantism
4.10
Entailment/implication
3.15
Error theory
4.12
Essence/accident
1.7
Fallacies
3.17
False cause
3.16
False dichotomy
6.4
Feminist and gender critiques
6.5
Foucaultian critique of power
3.18
Genetic fallacy
7.2
Gödel and incompleteness
5.4
Hegel’s master/slave dialectic
6.6
Heideggerian critique of metaphysics
7.3
Hermeneutic circle
3.19
Horned dilemmas
5.5
Hume’s fork
2.2
Hypothetico‐deductive method
5.6
Indirect discourse
1.3
Induction
4.13
Internalism/externalism
2.6
Intuition pumps
1.5
Invalidity
3.20
Is/ought gap
4.14
Knowledge by acquaintance/description
6.7
Lacanian critique
5.7
Leibniz’s law of identity
2.7
Logical constructions
3.21
Masked man fallacy
4.15
Mind/body
7.5
Mystical experience and revelation
4.16
Necessary/contingent
4.17
Necessary/sufficient
6.9
Nietzschean critique of Christian–Platonic culture
4.18
Nothingness/being
4.19
Objective/subjective
5.8
Ockham’s razor
7.6
Paradoxes
3.22
Partners in guilt
2.8
Performativity and speech acts
5.9
Phenomenological method(s)
7.4
Philosophy and/as art
7.7
Possibility and impossibility
6.10
Pragmatist critique
7.8
Primitives
3.23
Principle of charity
3.24
Question‐begging
4.20
Realist/non‐realist
2.9
Reduction
3.25
Reductios
3.26
Redundancy
1.8
Refutation
3.27
Regresses
2.10
Representation
6.11
Sartrean critique of ‘bad faith’
3.28
Saving the phenomena
7.10
Scepticism
3.29
Self‐defeating arguments
7.9
Self‐evident truths
4.21
Sense/reference
5.10
Signs and signifiers
4.22
Substratum/bundle
3.30
Sufficient reason
4.23
Syntax/semantics
1.12
Tautologies, self‐contradictions, and the law of non‐contradiction
3.31
Testability
4.25
Thick/thin concepts
2.11
Thought experiments
5.11
Transcendental argument
4.26
Types/tokens
7.11
Underdetermination
4.24
Universal/particular
2.12
Useful fictions
1.4
Validity and soundness
Preface
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 as well as 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 enter, analyse, criticise, and evaluate philosophical concepts, arguments, visions, 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. Or 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 book is assembled so that there is a natural, logical order from start to finish, but one can also start wherever one likes, just as one might play any song on a record album first. 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 third edition, we have expanded the book with sixteen new entries, and we’ve reviewed and revised most of the others. The book’s sections still progress from the basic tools of argumentation to more sophisticated philosophical concepts and principles. The text circulates through various instruments for assessment, essential laws, fundamental principles, and important conceptual distinctions. It concludes with a discussion of the limits of philosophical thinking. Through every chapter, the text opens entry points into complex topics of contemporary philosophical interest.
The Toolkit’s composition is intentionally pluralistic. By that we mean that we try to honour both the Continental and Anglo‐American traditions in philosophy. These two streams of Western philosophical thought have often been at odds, each regarding the other with critical suspicion and disdain. Though they have never been wholly distinct, the last major figure clearly rooting both is, arguably, eighteenth‐century philosopher Immanuel Kant (1724–1804). After Kant, the Continental tradition pursued lines of thinking charted through German and British idealism, phenomenology, existentialism, semiotics, structuralism, and various flavours of post‐structuralism, at times blending with literary criticism. Anglo‐American philosophy, in contrast, followed a course at first through empiricism, utilitarianism, and positivism, after which it then turned into pragmatism and analytic philosophy. This book is committed to the proposition that there is value in each tradition and that the richest and truest approach to philosophy draws from both.
The seven sections or chapters assembled here are composed of compact entries, each containing 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 – often in obvious ways but also sometimes in ways we think will be both novel and enlightening. Readers can chart their own path through the volume by following the cross‐references and recommended readings that interest them from one entry to the another. Recommended readings marked with an asterisk will be more accessible to readers and relatively less technical. There is also a list of Internet resources at the front of the book.
The readings we recommend are important recent and historical texts about which advanced readers ought to know. Recommended readings, however, also include introductory texts that will provide beginners with more extensive accounts of the relevant topic. Other recommended texts simply offer readers some indication of the range of import the topic has had.
Becoming a master sculptor requires more than the ability to pick up and use the tools of the trade: it requires talent, imagination, practice, persistence, and sometimes courage, too. In the same way, learning how to use these philosophical tools will not turn a beginner into a master of the art of philosophy overnight. What it will do is equip readers with skills, capacities, and techniques that will, we hope, help them philosophise better.
1Basic 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
1.1 Arguments, premises, and conclusions
Philosophy is for nit‐pickers. That’s not to say it is a trivial pursuit. Far from it. Philosophy addresses some of the most important questions human beings ask themselves. The reason philosophers are nit‐pickers is that they are commonly concerned with the ways in which the claims and beliefs people hold about the world either are or are not rationally supported, usually by rational argument. Because their concern is serious, it is important for philosophers to demand attention to detail. People reason in a variety of ways using a number of techniques, some legitimate and some not. Often one can discern the difference between good and bad reasoning only if one scrutinises the content and structure of arguments with supreme and uncompromising diligence.
Argument and inference
What, then, is an ‘argument’ proper? For many people, an argument is a contest or conflict between two or more people who disagree about something. An argument in this sense might involve shouting, name‐calling, and even a bit of shoving. It might also – but need not – include reasoning.
Philosophers, in contrast, use the term ‘argument’ in a very precise and narrow sense. For them, an argument is the most basic complete unit of reasoning – an atom of reasoning. An ‘argument’ understood this way is an inference from one or more starting points (truth claims called a ‘premise’ or ‘premises’) to an end point (a truth claim called a ‘conclusion’). All arguments require an inferential movement of this sort. For this reason, arguments are called discursive.
Argument vs explanation
‘Arguments’ are to be distinguished from ‘explanations’. A general rule to keep in mind is that arguments attempt to demonstrate that something is true, while explanations attempt to show how something is true. For example, consider encountering an apparently dead woman. An explanation of the woman’s death would undertake to show how it happened. (‘The existence of water in her lungs explains the death of this woman.’) An argument would undertake to demonstrate that the person is in fact dead (‘Since her heart has stopped beating and there are no other vital signs, we can conclude that she is in fact dead.’) or that one explanation is better than another (‘The absence of bleeding from the laceration on her head combined with water in the lungs indicates that this woman died from drowning and not from bleeding.’)
The place of reason in philosophy
It’s not universally realised that reasoning comprises a great deal of what philosophy is about. Many people have the idea that philosophy is essentially about ideas or theories about the nature of the world and our place in it that amount just to opinions. Philosophers do indeed advance such ideas and theories, but in most cases their power, their scope, and the characteristics that distinguish them from mere opinion stem from their having been derived through rational argument from acceptable premises. Of course, many other regions of human life also commonly involve reasoning, and it may sometimes be impossible to draw clean lines demarcating philosophy from them. (In fact, whether or not it is possible to demarcate philosophy from non‐philosophy is itself a matter of heated philosophical debate!)
The natural and social sciences are, for example, fields of rational inquiry that often bump up against the borders of philosophy (especially in inquiries into the mind and brain, theoretical physics, and anthropology). But theories composing these sciences are generally determined through certain formal procedures of experimentation and reflection to which philosophy has little to add. Religious thinking sometimes also enlists rationality and shares an often‐disputed border with philosophy. But while religious thought is intrinsically related to the divine, sacred, or transcendent – perhaps through some kind of revelation, article of faith, or ritualistic practice – philosophy, by contrast, in general is not.
Of course, the work of certain prominent figures in the Western philosophical tradition presents decidedly non‐rational and even anti‐rational dimensions (for example, that of Heraclitus, Kierkegaard, Nietzsche, Heidegger, and Derrida). We will examine the non‐argumentative philosophical methods of these authors in what follows of this book. Furthermore, many include the work of Asian (Confucian, Taoist, Shinto), African, Aboriginal, and Native American thinkers under the rubric of philosophy, even though they seem to make little use of argument and have generally not identified their work as philosophical.
But, perhaps despite the intentions of its authors, even the work of non‐standard thinkers involves rationally justified claims and subtle forms of argumentation too often missed. And in many cases, reasoning remains on the scene at least as a force with which thinkers must reckon.
Philosophy, then, is not the only field of thought for which rationality is important. And not all that goes by the name of philosophy is argumentative. But it is certainly safe to say that one cannot even begin to master the expanse of philosophical thought without learning how to use the tools of reason. There is, therefore, no better place to begin stocking our philosophical toolkit than with rationality’s most basic components, the subatomic particles of reasoning – ‘premises’ and ‘conclusions’.
Premises and conclusions
For most of us, the idea of a ‘conclusion’ is as straightforward as a philosophical concept gets. A conclusion is just that with which an argument concludes, the product and result of an inference or a chain of inferences, that which the reasoning claims to justify and support. What about ‘premises’, though? Premises are defined in relation to the conclusion. They are, of course, what do the justifying. There is, however, a distinctive and a bit less obvious property that all premises and conclusions must possess.
In order for a sentence to serve either as a premise or as a conclusion, it must exhibit this essential property: it must make a claim that is either true or false. A sentence that does that is in logical terms called a statement or proposition.
Sentences do many things in our languages, and not all of them possess that property and thence not all of them are statements. Sentences that issue commands, for example (‘Forward march, soldier!’), or ask questions (‘Is this the road to Edinburgh?’), or register exclamations (‘Wow!’), are neither true nor false. Hence, it’s not possible for sentences of those kinds to serve as premises or as conclusions.
This much is pretty easy, but things can get sticky in a number of ways. One of the most vexing issues concerning arguments is the problem of implicit claims. That is, in many arguments, key premises or even the conclusion remain unstated, implied or masked inside other sentences. Take, for example, the following argument: ‘Socrates is a man, so Socrates is mortal.’ What’s left implicit is the claim that ‘all men are mortal’. Arguments with unstated premises like this are often called enthymemes or enthymemetic.
It’s also the case that sometimes arguments nest inside one another so that in the course of advancing one, main conclusion several ancillary conclusions are proven along the way. Untangling arguments nested in others can get complicated, especially as those nests can pile on top of one another and interconnect. It often takes a patient, analytical mind to sort it all out (just the sort of mind you’ll encounter among philosophers).
In working out precisely what the premises are in a given argument, then, ask yourself first what the principal claim is that the argument is trying to demonstrate. Then ask yourself what other claims the argument relies upon (implicitly or explicitly) in order to advance that demonstration. Sometimes certain words and phrases will explicitly indicate premises and conclusions. Phrases like ‘therefore’, ‘in conclusion’, ‘it follows that’, ‘we must conclude that’, and ‘from this we can see that’ often indicate conclusions. (‘The DNA, the fingerprints, and the eyewitness accounts all point to Smithers. It follows that she must be the killer.’) Words like ‘because’ and ‘since’, and phrases like ‘for this reason’ and ‘on the basis of this’, on the other hand, often indicate premises. (For example, ‘Since the DNA, the fingerprints, and the eyewitness accounts all implicate Smithers, she must be the killer.’)
Premises of an argument, then, compose the set of claims from which the conclusion is drawn. In other sections, the question of precisely how we can justify the move from premises to conclusion will be addressed in more in more detail (see 1.4 and 4.7). But before we get that far, we must first ask, ‘What justifies a reasoner in entering a premise in the first place?’
Grounds for premises and Agrippa’s trilemma?
There are several important accounts about how a premise can be acceptable. One is that the premise is itself the conclusion of a different, solid argument (perhaps a nested argument). As such, the truth of the premise has been demonstrated elsewhere. But it is clear that if this were the only kind of justification for the inclusion of a premise, we would face an infinite regress. That is to say, each premise would have to be justified by a different argument, the premises of which would have to be justified by yet another argument, the premises of which … ad infinitum.
Now, there are philosophers called infinitists for whom regresses of this sort are not problematic. Unless, however, one wishes to live with the infinite regress, one must find another way of determining sentences acceptable to serve as premises.
A compelling option for many has been to conceive of truths not as a hierarchy but rather as a network so that it’s the case that justifications ultimately just circle back around to compose a coherent, mutually supporting but ultimately anchor‐less web. The objective of philosophers and other theorists, from this point of view, becomes a project of conceptual weaving and embroidery, stitching together concepts and arguments in consistent and meaningful ways to construct a coherent conceptual fabric. Philosophers who conceive of truths, theories, and reasoning in this way are called coherentists.
Philosophers who object to infinite regresses of justification and who find in the coherentist vision just vicious circularity often look for something fundamental or foundational, a stopping point or bedrock for reasons and justification. Philosophers of this sort are often called foundationalists. There must be for foundationalists premises that stand in need of no further justification through other arguments. Let’s call them ‘basic premises’.
There’s been a lot of ink spilled about what are to count as basic premises and why they are basic. By some accounts (called contextualist), the local context in which one is reasoning determines what’s basic. For example, a basic premise might be, ‘I exist’. In most contexts, this premise does not stand in need of justification. But if, of course, the argument is trying to demonstrate that I exist, my existence cannot be used as a premise. One cannot assume what one is trying to argue for.
Other kinds of philosophers have held that certain sentences are more or less basic for other reasons: because they are based upon self‐evident or ‘cataleptic’ perceptions (stoics), because they are directly rooted in sense data (positivists), because they are grasped by a power called intuition or insight (Platonists), because they make up the framework of any possible inquiry and therefore cannot themselves be the objects of inquiry (Kantians, Wittgensteinians), because they are revealed to us by God (theologians), or because we grasp them using cognitive faculties certified by God (Cartesians).
Other philosophers, principally sceptics, have challenged the idea that an ultimate ground can be given at all for reasoning. Appeals to neither (1) regresses, nor (2) circles, nor (3) foundations ultimately work. The problem is an old one and has been popularly described as ‘Agrippa’s trilemma’. See Graeco‐Roman Diogenes Laëritus’s Lives of Eminent Philosophers (9.88–89) and Sextus Empiricus’s Outlines of Pyrrhonism (PH 1.15.164) for the details.
Formally, then, the distinction between premises and conclusions is clear. But it is not enough to grasp this difference. In order to use these philosophical tools, one has to be able both to spot the explicit premises and to make explicit the unstated ones. The philosophical issues behind that distinction, however, are deep. Aside from the question of whether or not the conclusion follows from the premises, one must come to terms with the thornier questions related to what justifies the use of premises in the first place. Premises are the starting points of philosophical argument. One of the most important philosophical issues, therefore, must be the question of where and how one begins.
SEE ALSO
1.10 Definitions
3.7 Circularity
7.1 Basic beliefs
7.9 Self‐evident truths
READING
* Nigel Warburton (2000).
Thinking From A to Z
, 2nd edn
John Shand (2000).
Arguing Well
* Graham Priest (2001).
Logic: A Very Short Introduction
Peter Klein (2008). ‘Contemporary responses to Agrippa’s trilemma' in
The Oxford Handbook of Skepticism
(ed. John Greco)
1.2 Deduction
The murder was clearly premeditated, Watson. The only person who knew where Dr Fishcake would be that night was his colleague, Dr Salmon. Therefore, the killer must be …
Deduction is the form of reasoning that is often emulated in the formulaic drawing‐room denouements of classic detective fiction. It is the most rigorous form of argumentation there is, since in deduction the move from premises to conclusions is such that if the premises are true, then the conclusion must (necessarily) also be true. For example, take the following argument:
Elvis Presley lives in a secret location in Idaho.
All people who live in secret locations in Idaho are miserable.
Therefore, Elvis Presley is miserable.
If we look at our definition of a deduction, we can see how this argument fits the bill. If the two premises are true, then the conclusion must also definitely be true. How could it not be true that Elvis is miserable, if it is indeed true that all people who live in secret locations in Idaho are miserable, and Elvis is one of those people?
You might well be thinking there’s something fishy about this, since you may believe that Elvis is not miserable for the simple reason that he no longer exists. So, all this talk of the conclusion having to be true might strike you as odd. If this is so, you haven’t taken on board the key word at the start of this sentence, which does such vital work in the definition of deduction. The conclusion must be true if the premises are true. This is a big ‘if’. In our example, the conclusion is, we confidently believe, not true and for very good reasons. But that doesn’t alter the fact that this is a deductive argument, since if it turned out that Elvis does live in a secret location in Idaho and that all people who lived in secret locations in Idaho are miserable, it would necessarily follow that Elvis is miserable.
The question of what makes a good deductive argument is addressed in more detail in the section on validity and soundness (1.4). But in a sense, everything that you need to know about a deductive argument is contained within the definition just given: a (successful) deductive argument is one where, if the premises are true, then the conclusion is definitely true.
Before we leave this topic, however, we should return to the investigations pursued by our detective. Reading his deliberations, one could easily insert the vital, missing words. The killer must surely be Dr Salmon. But is this the conclusion of a successful deductive argument? The fact is that we can’t answer this question unless we know a little more about the exact meaning of the premises.
First, what does it mean to say the murder was ‘premeditated’? It could mean lots of things. It could mean that it was planned right down to the last detail, or it could mean simply that the murderer had worked out what she would do in advance. If it is the latter, then it is possible that the murderer did not know where Dr Fishcake would be that night, but, coming across him by chance, put into action her premeditated plan to kill him. So, it could be the case (1) that both premises are true (the murder was premeditated, and Dr Salmon was the only person who knew where Dr Fishcake would be that night) but (2) that the conclusion is false (Dr Salmon is, in fact, not the murderer). Therefore, the detective has not formed a successful deductive argument.
What this example shows is that, although the definition of a deductive argument is simple enough, spotting and constructing successful deductive arguments is much trickier. To judge whether or not the conclusion really must follow from the premises, you have to be sensitive to ambiguity in the premises as well as to the danger of accepting too easily a conclusion that seems to be supported by the premises but does not in fact follow from them. Deduction is not about jumping to conclusions, but crawling (though not slouching) slowly towards them.
SEE ALSO
1.1 Arguments, premises, and conclusions
1.3 Induction
1.4 Validity and soundness
READING
* Alfred Tarski (1936/95).
Introduction to Logic and to the Methodology of Deductive Sciences
* Fred R. Berger (1977).
Studying Deductive Logic
* A.C. Grayling (2001).
An Introduction to Philosophical Logic
Warren Goldfarb (2003).
Deductive Logic
* Maria Konnikova (2013).
Mastermind: How to Think Like Sherlock Holmes
1.3 Induction
I (Julian Baggini) have a confession to make. Once, while on holiday in Rome, I visited the famous street market, Porta Portese. I came across a man who was taking bets on which of the three cups he had shuffled around was covering a die. I will spare you the details and any attempts to justify my actions on the grounds of mitigating circumstances. Suffice it to say, I took a bet and lost. Having been budgeted so carefully, the cash for that night’s pizza went up in smoke.
My foolishness in this instance is all too evident. But is it right to say my decision to gamble was ‘illogical’? Answering this question requires wrangling with a dimension of logic philosophers call ‘induction’. Unlike deductive inferences, induction involves an inference where the conclusion follows from the premises not with necessity or definitely but only with probability (though even this formulation is problematic, as we’ll see).
Defining induction
Perhaps most familiar to people is a kind of induction that involves reasoning from a limited number of observations to wider generalisations of some probability. Reasoning this way is commonly called inductive generalisation. It’s a kind of inference that usually involves reasoning from past regularities to future regularities. One classic example is the sunrise. The sun has risen regularly each day, so far as human experience can recall, so people reason that it will probably rise tomorrow. This sort of inference is often taken to typify induction. In the case of my Roman holiday, I might have reasoned that the past experiences of people with average cognitive abilities like mine show that the probabilities of winning against the man with the cups is rather small.
But beware: induction is not essentially defined as reasoning from the specific to the general. An inductive inference need not be past–future directed. And it can involve reasoning from the general to the specific, the specific to the specific, or the general to the general.
I could, for example, reason from the more general, past‐oriented claim that no trained athlete on record has been able to run 100 metres in under 9 seconds, to the more specific past‐oriented conclusion that my friend had probably not achieved this feat when he was at university, as he claims. Reasoning through analogies (see 2.4) as well as typical examples and rules of thumb are also species of induction, even though none of them involves moving from the specific to the general. The important property of inductive inferences is that they determine conclusions only with probability, not how they relate specific and general claims.
The problem of induction
Although there are lots of kinds of induction besides inductive generalisations, that species of induction is, when it comes to actual practices of reasoning, often where the action is. Reasoning in experimental science, for example, commonly depends on inductive generalisations in so far as scientists formulate and confirm universal natural laws (e.g. Boyle’s ideal gas law) only with a degree of probability based upon a relatively small number of observations. Francis Bacon (1561–1626) argued persuasively for just this conception of induction.
The tricky thing to keep in mind about inductive generalisations, however, is that they involve reasoning from a ‘some’ in a way that in deduction would require an ‘all’ (where ‘some’ means at least one but perhaps not all of some set of relevant individuals). Using a ‘some’ in this way makes inductive generalisation fundamentally different from deductive argument (for which such a move would be illegitimate). It also opens up a rather enormous can of conceptual worms. Philosophers know this conundrum as the problem of induction. Here’s what we mean. Take the following example:
Almost all
elephants like chocolate.
This is an elephant.
Therefore, this elephant likes chocolate.
This is not a well‐formed deductive argument, since the premises could possibly be true and the conclusion still be false. Properly understood, however, it may be a strong inductive argument – if the conclusion is taken to be probable, rather than certain.
On the other hand, consider this rather similar argument:
All
elephants like chocolate.
This is an elephant.
Therefore, this elephant likes chocolate.
Though similar in certain ways, this one is, in fact, a well‐formed deductive argument, not an inductive argument at all. One way to think of the problem of induction, therefore, is as the problem of how an argument can be good reasoning as induction but be poor reasoning as a deduction. Before addressing this problem directly, we must take care not to be misled by the similarities between the two forms.
A misleading similarity
Because of the general similarity one sees between these two arguments, inductive arguments can sometimes be confused with deductive arguments. That is, although they may actually look like deductive arguments, some arguments are actually inductive. For example, an argument that the sun will rise tomorrow might be presented in a way that can easily be taken for a deductive argument:
The sun rises every day.
Tomorrow is a day.
Therefore, the sun will rise tomorrow.
Because of its similarity with deductive forms, one may be tempted to read the first premise as an ‘all’ sentence:
The sun rises on all days (every 24‐hour period) that there ever have been and ever will be.
The limitations of human experience, however (the fact that we can’t experience every single day), justify us in forming only the less strong ‘some’ sentence:
The sun has risen on every day (every 24‐hour period) that humans have recorded their experience of such things.
This weaker formulation, of course, enters only the limited claim that the sun has risen on a small portion of the total number of days that have ever been and ever will be; it makes no claim at all about the rest.
But here’s the catch. From this weaker ‘some’ sentence, one cannot construct a well‐formed deductive argument of the kind that allows the conclusion to follow with the kind of certainty characteristic of deduction. In reasoning about matters of fact, one would like to reach conclusions with the certainty of deduction. Unfortunately, induction will not allow it. There’s also another more complex problem lurking here that’s perplexed philosophers: induction seems viciously circular. It seems in fact to assume the very thing it’s trying to prove. Consider the following.
Assuming the uniformity of nature?
Put at its simplest, the problem of induction can be boiled down to the problem of justifying our belief in the uniformity of nature or even reality across space and time. If nature is uniform and regular in its behaviour, then what’s been observed past and present (i.e. premises of an induction) is a sure guide to the so far unobserved past, present, and future (i.e. the conclusion of an induction).
The only basis, however, for believing that nature is uniform is the observed past and present. We can’t then, it seems, go beyond observed events without assuming the very thing we need to prove – that is, that unobserved parts of the world operate in the same way as the parts we observe. In short, inductively proving that some bit of the world is like other bits requires already assuming that uniformities of that sort hold.
Induction undertakes to prove the world to be uniform in specific ways; but inductive inference already assumes that the world is relevantly uniform.
We can infer inductively that the sun will rise tomorrow on the basis of what it’s done in the past (i.e. that the future will resemble the past) only if we already assume that the future will resemble the past. Eighteenth‐century Scot David Hume has remained an important philosopher in part precisely for his analysis of this problem.
Believing, therefore, that the sun may possibly not rise tomorrow is, strictly speaking, not illogical, since the conclusion that it must rise tomorrow does not inexorably follow from past observations.
A deeper complexity
Acknowledging the relative weakness of inductive inferences (compared to those of deduction), good reasoners qualify the conclusions reached through it by maintaining that they follow not with necessity but only with probability (i.e. it’s just highly probably that the sun will rise tomorrow). But does this fully resolve the problem? Can even this weaker, more qualified formulation be justified? Can we, for example, really justify the claim that, on the basis of uniform and extensive past observation, it is more probable than not that the sun will rise tomorrow?
The problem is that there is no deductive argument to ground even this qualified claim. To deduce this conclusion successfully we would need the premise ‘what has happened up until now is more likely to happen tomorrow’. But this premise is subject to just the same problem as the stronger claim that ‘what has happened up until now must happen tomorrow’. Like its stronger counterpart, the weaker premise bases its claim about the future only on what has happened up until now, and such a basis can be justified only if we already accept the uniformity (or at least probable continuity) of nature. But again, the uniformity (or continuity) of nature is just what’s in question.
A groundless ground?
Despite these problems, it seems that we can’t do without inductive generalisations and inductive reasoning generally. They are (or at least have been so far!) simply too useful to refuse. Inductive generalisations compose the basis of much of our scientific rationality, and they allow us to think about matters concerning which deduction must remain silent. In short, we simply can’t afford to reject the premise that ‘what we have so far observed is our best guide to what is true of what we haven’t observed’, even though this premise cannot itself be justified without presuming itself.
There is, however, a price to pay. We must accept that engaging in inductive generalisation requires that we hold an indispensable belief which itself, however, must remain in an important way unjustified. As Hume puts it: ‘All our experimental conclusions proceed upon the supposition that the future will be conformable to the past. To endeavour, therefore, the proof of this last supposition by probable arguments … must be evidently going in a circle, and taking that for granted, which is the very point in question’ (Enquiry Concerning Human Understanding, 4.19). Can we accept reasoning and sciences that are ultimately groundless?
SEE ALSO
1.1 Arguments, premises, and conclusions
1.2 Deduction
1.7 Fallacies
2.4 Analogies
5.5 Hume’s fork
READING
Francis Bacon (1620).
Novum Organum
David Hume (1739).
A Treatise of Human Nature
, Bk 1, Part 3, Section 6
D.C. Stove (1986/2001).
The Rationality of Induction
* Colin Howson (2003).
Hume’s Problem: Induction and the Justification of Belief
1.4 Validity and soundness
In his book, The Unnatural Nature of Science, the eminent British biologist Lewis Wolpert (b. 1929) argued that the one thing that unites almost all of the sciences is that they often fly in the face of common sense. Philosophy, however, may exceed even the (other?) sciences on this point. Its theories, conclusions, and terms can at times be extraordinarily counterintuitive and contrary to ordinary ways of thinking, doing and speaking.
Take, for example, the word ‘valid’. In everyday speech, people talk about someone ‘making a valid point’ or ‘having a valid opinion’. In philosophical speech, however, the word ‘valid’ is reserved exclusively for arguments. More surprisingly, a valid argument can look like this:
All blocks of cheese are more intelligent than any philosophy student.
Meg the cat is a block of cheese.
Therefore, Meg the cat is more intelligent than any philosophy student.
All utter nonsense, you may think, but from a strictly logical point of view this is a perfect example of a valid argument. How can that be so?
Defining validity
Validity is a property of well‐formed deductive arguments, which, to recap, are defined as arguments where the conclusion in some sense (actually, hypothetically, etc.) follows from the premises necessarily (see 1.2). Calling a deductive argument ‘valid’ affirms that the conclusion does follow from the premises in that way. Arguments that are presented as or taken to be successful deductive arguments, but where the conclusion does not in fact definitely follow from the premises, are called ‘invalid’ deductive arguments.
The tricky thing, in any case, is that an argument may possess the property of validity even if its premises or its conclusion are not in fact true. Validity, as it turns out, is essentially a property of an argument’s structure or form; and so, the content and truth value of the statements composing the argument are irrelevant. Let’s unpack this.
Consider structure first. The argument featuring cats and cheese given above is an instance of a more general argumentative structure, of the form:
All Xs are Ys.
Z is an X.
Therefore, Z is a Y.
In our example, ‘block of cheese’ is substituted for X, ‘things that are more intelligent than all philosophy students’ for Y, and ‘Meg’ for Z. That makes our example just one particular instance of the more general argumentative form expressed with the variables X, Y, and Z.
What you should notice is that you don’t need to attach any particular meaning to the variables for this particular form to be a valid one. No matter with what we replace the variables, it will always be the case that if the premises are true (even though in fact they might not be), the conclusion must also be true. If there’s any conceivable way possible for the premises of an argument to be true but its conclusion simultaneously be false, any coherent way at all, then it’s an invalid argument.
This boils down to the notion of validity as content‐blind or topic‐neutral. It really doesn’t matter what the content of the propositions in the argument is – validity is determined by the argument having a solid, deductive structure. Our block‐of‐cheese example is then a valid argument, because if its ridiculous premises were true, the ridiculous conclusion would also have to be true. The fact that the premises are ridiculous is neither here nor there when it comes to assessing the argument’s validity.
The truth machine
Another way of understanding how arguments work as to think of them along the model of sausage machines. You put ingredients (premises) in, and then you get something (conclusions) out. Deductive arguments may be thought of as the best kind of sausage machine because they guarantee their output in the sense that when you put in entirely good ingredients (all true premises), you get out a fine‐quality product (true conclusions). Of course, if you don’t start with good ingredients, deductive arguments don’t guarantee a good end product.
Invalid arguments are not generally desirable machines to employ. They provide no guarantee whatsoever for the quality of the end product. You might put in good ingredients (true premises) and sometimes get a high‐quality result (a true conclusion). Other times good ingredients might yield a frustratingly poor result (a false conclusion).
Stranger still (and very different from sausage machines), with invalid deductive arguments you might sometimes put in poor ingredients (one or more false premises) but actually end up with a good result (a true conclusion). Of course, in other cases with invalid machines you put in poor ingredients and end up with rubbish. The thing about invalid machines is that you don’t know what you’ll get out. With valid machines, when you put in good ingredients (though only when you put in good ingredients), you have assurance. In sum:
Invalid argument
Put in false premise(s) → get out either a true or false conclusion
Put in true premise(s) → get out either a true or false conclusion
Valid argument
Put in false premise(s) → get out either a true or false conclusion
Put in true premise(s) → get out always and only a true conclusion
Soundness
To say an argument is valid, then, is not to say that its conclusion must be accepted as true. The conclusion is definitely established as true only if both of two conditions are met: (1) the argument is valid and (2) the premises are true. This combination of valid argument plus true premises (and therefore a true conclusion) is called approvingly a sound argument. Calling it sound is the highest endorsement one can give an argument. If you accept an argument as sound, you are really saying that one must accept its conclusion. The idea of soundness can even itself be formulated as an especially instructive valid, deductive argument:
If the premises of the argument are true, then the conclusion must also be true (i.e. the argument is valid).
The premises of the argument are true.
Therefore, the conclusion of the argument must also be true.
For a deductive argument to pass muster, it must be valid. But being valid is by itself not sufficient to make it a sound argument. A sound argument must not only be valid; it must have true premises, as well. It is, strictly speaking, only sound arguments whose conclusions we must accept.
Importance of validity
This may lead you to wonder why, then, the concept of validity has any importance. After all, valid arguments can be absurd in their content and false in their conclusions – as in our cheese and cats example. Surely it is soundness that matters?
Okay, but keep in mind that validity is a required component of soundness, so there can be no sound arguments without valid ones. Working out whether or not the claims you make in your premises are true, while important, is also not enough to ensure that you draw true conclusions. People make this mistake all the time. They forget that one can begin with a set of entirely true beliefs but reason so poorly as to end up with entirely false conclusions. It can be crucial to remember that starting with truth doesn’t guarantee ending up with it.
Furthermore, for the sake of launching criticisms, it is important to grasp that understanding validity gives you an additional tool for evaluating another’s position. In criticising a specimen of reasoning, you can either:
attack the truth claims of the premises from which he or she reasons,
or show that his or her argument is invalid, regardless of whether or not the premises deployed are true.
Validity is, simply put, a crucial ingredient in arguing, criticising, and thinking well, even if not the only ingredient. It’s an utterly indispensable philosophical tool. Master it.
SEE ALSO
1.1 Arguments, premises, and conclusions
1.2 Deduction
1.5 Invalidity
READING
Aristotle (384–322
BCE
).
Prior Analytics
Fred R. Berger (1977).
Studying Deductive Logic
S.K. Langer (2011). ‘Truth and validity'. In:
Introduction to Symbolic Logic
, 3rd edn, Ch. 1, pp. 182–90
* Jc Beall and Shay Allen Logan (2017).
Logic: The Basics
, 2nd edn
1.5 Invalidity
Given the definition of a valid argument, it may seem obvious what an invalid one looks like. Certainly, it’s simple enough to define an invalid argument: it is an argument where the truth of the premises does not guarantee the truth of the conclusion. To put it another way, if the premises of an invalid argument are true, the conclusion may still be false. Invalid arguments are unsuccessful deductions and therefore, in a sense, are not truly deductions at all.
To be armed with an adequate definition of invalidity, however, may not be enough to enable you to make use of this tool. The man who went looking for a horse equipped only with the definition ‘solid‐hoofed, herbivorous, domesticated mammal used for draught work and riding’ (Collins English Dictionary) discovered as much, to his cost. In addition to the definition, you need to understand the definition’s full import. Consider this argument:
Vegetarians do not eat pork sausages.
Gandhi did not eat pork sausages.
Therefore, Gandhi was a vegetarian.
If you’re thinking carefully, you’ll have probably noticed that this is an invalid argument. But it wouldn’t be surprising if you and a fair number of readers required a double take to see that it is in fact invalid. Now, this is a clear case, and if a capable intellect can easily miss a clear case of invalidity in the midst of an article devoted to a careful explanation of the concept, imagine how easy it is not to spot invalid arguments more generally.
One reason why many will fail to notice that this argument is invalid is because all three propositions are true. If nothing false is asserted in the premises of an argument and the conclusion is true, it’s easy to think that the argument is therefore valid (and sound). But remember that an argument is valid only if the truth of the premises guarantees
