Informal logic
Encyclopedia
Informal logic, intuitively, refers to the principles of logic
and logical thought outside of a formal
setting. However, perhaps because of the informal in the title, the precise definition of informal logic is matters of some dispute. Ralph H. Johnson
and J. Anthony Blair define informal logic as "a branch of logic whose task is to develop non-formal standards, criteria, procedures for the analysis, interpretation, evaluation, criticism and construction of argumentation." This definition reflects what had been implicit in their practice and what others were doing in their informal logic texts.
Informal logic is associated with (informal) fallacies, critical thinking
, the Thinking Skills Movement and the interdisciplinary inquiry known as argumentation theory
. Frans H. van Eemeren writes that the label "informal logic" covers a "collection of normative approaches to the study of reasoning in ordinary language that remain closer to the practice of argumentation than formal logic."
. The naming of the field was preceded by the appearance of a number of textbooks that rejected the symbolic approach to logic
on pedagogical grounds as inappropriate and unhelpful for introductory textbooks on logic for a general audience, for example Howard Kahane
’s Logic and Contemporary Rhetoric, subtitled “The Use of Reason in Everyday Life”, first published in 1971. Kahane's textbook was described on the notice of his death in the Proceedings And Addresses of the American Philosophical Association (2002) as "a text in informal logic, [that] was intended to enable students to cope with the misleading rhetoric one frequently finds in the media and in political discourse. It was organized around a discussion of fallacies, and was meant to be a practical instrument for dealing with the problems of everyday life. [It has] ... gone through many editions; [it is] ... still in print; and the thousands upon thousands of students who have taken courses in which his text [was] ... used can thank Howard for contributing to their ability to dissect arguments and avoid the deceptions of deceitful rhetoric. He tried to put into practice the ideal of discourse that aims at truth rather than merely at persuasion. (Hausman et al. 2002)" Other textbooks from the era taking this approach were Michael Scriven
’s Reasoning (Edgepress, 1976) and Logical Self-Defense by Ralph H. Johnson
and J. Anthony Blair, first published in 1977. Earlier precursors in this tradition can be considered Monroe Beardsley
's Practical Logic (1950) and Stephen Toulmin
's The Uses or Argument (1958).
The field perhaps became recognized under its current name with the First International Symposium on Informal Logic held in 1978. Although initially motivated by a new pedagogical approach to undergraduate logic textbooks, the scope of the field was basically defined by a list 13 of problems and issues which Blair and Johnson included as an appendix to their keynote address at this symposium:
David Hitchcock argues that the naming of the field was unfortunate, and that philosophy of argument would have been more appropriate. He argues that more undergraduate students in North America study informal logic than any other branch of philosophy, but that as of 2003 informal logic (or philosophy of argument) was not recognized as separate sub-field by the World Congress of Philosophy
. Frans H. van Eemeren wrote that "informal logic" is mainly an approach to argumentation advanced by a group of US and Canadian philosophers and largely based on the previous works of Stephen Toulmin
and to a lesser extent those of Chaïm Perelman
.
Alongside the symposia, since 1983 the journal Informal Logic has been the publication of record of the field, with Blair and Johnson as initial editors, with the editorial board now including two other colleagues from the University of Windsor
—Christopher Tindale and Hans V. Hansen. Other journals that regularly publish articles on informal logic include Argumentation (founded in 1986), Philosophy and Rhetoric, Argumentation and Advocacy
(the journal of the American Forensic Association
), and Inquiry: Critical Thinking Across the Disciplines
(founded in 1988).
To understand the definition above, one must understand "informal" which takes its meaning in contrast to its counterpart "formal." (This point was not made for a very long time, hence the nature of informal logic remained opaque, even to those involved in it, for a period of time.) Here it is helpful to have recourse to Barth and Krabbe (1982:14f) where they distinguish three senses of the term "form." By "form1," Barth and Krabbe mean the sense of the term which derives from the Plato
nic idea of form
—the ultimate metaphysical
unit. Barth and Krabbe claim that most traditional logic is formal in this sense. That is, syllogistic logic is a logic of terms where the terms could naturally be understood as place-holders for Platonic (or Aristotelian
) forms. In this first sense of "form," almost all logic is informal (not-formal). Understanding informal logic this way would be much too broad to be useful.
By "form2," Barth and Krabbe mean the form of sentences and statements as these are understood in modern systems of logic. Here validity
is the focus: if the premise
s are false, the conclusion must then also be true. Now validity has to do with the logical form
of the statement that makes up the argument. In this sense of "formal," most modern and contemporary logic is "formal." That is, such logics canonize the notion of logical form, and the notion of validity plays the central normative role. In this second sense of form, informal logic is not-formal, because it abandons the notion of logical form as the key to understanding the structure
of arguments, and likewise retires validity as normative for the purposes of the evaluation of argument. It seems to many that validity is too stringent a requirement, that there are good arguments in which the conclusion is supported by the premises even though it does not follow necessarily from them (as validity requires). An argument in which the conclusion is thought to be "beyond reasonable doubt, given the premises" is sufficient in law to cause a person to be sentenced to death
, even though it does not meet the standard of logical validity. This type of argument, based on accumulation of evidence rather than pure deduction
, is called a conductive argument.
By "form3," Barth and Krabbe mean to refer to "procedures which are somehow regulated or regimented, which take place according to some set of rules." Barth and Krabbe say that "we do not defend formality3 of all kinds and under all circumstances." Rather "we defend the thesis that verbal dialectic
s must have a certain form (i.e., must proceed according to certain rules) in order that one can speak of the discussion as being won or lost" (19). In this third sense of "form", informal logic can be formal, for there is nothing in the informal logic enterprise that stands opposed to the idea that argumentative discourse
should be subject to norms, i.e., subject to rules, criteria, standards or procedures. Informal logic does present standards for the evaluation of argument, procedures for detecting missing premises etc.
Johnson and Blair (2000) noticed a limitation of their own definition, particularly with respect to "everyday discourse", which could indicate that it does not seek to understand specialized, domain-specific arguments made in natural languages. Consequently, they have argued that the crucial divide is between arguments made in formal language
s and those made in natural language
s.
Fisher and Scriven (1997) proposed a more encompassing definition, seeing informal logic as "the discipline which studies the practice of critical thinking and provides its intellectual spine". By "critical thinking" they understand "skilled and active interpretation and evaluation of observations and communications, information and argumentation."
of an argument aside from the formal method, and that the study of fallacies may be of more interest to other disciplines, like psychology
, than to philosophy and logic.
" is a subject of much dispute. Critical thinking, as defined by Johnson, is the evaluation of an intellectual product (an argument, an explanation, a theory) in terms of its strengths and weaknesses. While critical thinking will include evaluation of arguments and hence require skills of argumentation including informal logic, critical thinking requires additional abilities not supplied by informal logic, such as the ability to obtain and assess information and to clarify meaning. Also, many believe that critical thinking requires certain dispositions. Understood in this way, "critical thinking" is a broad term for the attitudes and skills that are involved in analyzing and evaluating arguments. The critical thinking movement promotes critical thinking as an educational ideal. The movement emerged with great force in the 80s in North America as part of an ongoing critique of education as regards the thinking skills not being taught.
)—a relationship between propositions; and from inference—a mental activity typically thought of as the drawing of a conclusion from premises. Informal logic may thus be said to be a logic of argumentation, as distinguished from implication and inference.
Argumentation theory (or the theory of argumentation) has come to be the term that designates the theoretical study of argumentation. This study is interdisciplinary in the sense that no one discipline will be able to provide a complete account. A full appreciation of argumentation requires insights from logic (both formal and informal), rhetoric, communication theory, linguistics, psychology, and, increasingly, computer science. Since the 1970s, there has been significant agreement that there are three basic approaches to argumentation theory: the logical, the rhetorical and the dialectical. According to Wenzel, the logical approach deals with the product, the dialectical with the process, and the rhetorical with the procedure. Thus, informal logic is one contributor to this inquiry, being most especially concerned with the norms of argument.
issue 20(2) of Informal Logic from year 2000 groups a number of papers addressing foundational issues, based on the Panel on Informal Logic that was held at the 1998 World Congress of Philosophy, including:
Logic
In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...
and logical thought outside of a formal
Formal logic
Classical or traditional system of determining the validity or invalidity of a conclusion deduced from two or more statements...
setting. However, perhaps because of the informal in the title, the precise definition of informal logic is matters of some dispute. Ralph H. Johnson
Ralph Johnson (philosopher)
Ralph H. Johnson is a native of Detroit, Michigan. Johnson has been credited as one of the founding members of the informal logic movement in North America, along with J. Anthony Blair who co-published one of the movement’s most influential texts, “Logical Self-Defense,” with Johnson...
and J. Anthony Blair define informal logic as "a branch of logic whose task is to develop non-formal standards, criteria, procedures for the analysis, interpretation, evaluation, criticism and construction of argumentation." This definition reflects what had been implicit in their practice and what others were doing in their informal logic texts.
Informal logic is associated with (informal) fallacies, critical thinking
Critical thinking
Critical thinking is the process or method of thinking that questions assumptions. It is a way of deciding whether a claim is true, false, or sometimes true and sometimes false, or partly true and partly false. The origins of critical thinking can be traced in Western thought to the Socratic...
, the Thinking Skills Movement and the interdisciplinary inquiry known as argumentation theory
Argumentation theory
Argumentation theory, or argumentation, is the interdisciplinary study of how humans should, can, and do reach conclusions through logical reasoning, that is, claims based, soundly or not, on premises. It includes the arts and sciences of civil debate, dialogue, conversation, and persuasion...
. Frans H. van Eemeren writes that the label "informal logic" covers a "collection of normative approaches to the study of reasoning in ordinary language that remain closer to the practice of argumentation than formal logic."
History
Informal logic as a distinguished enterprise under this name emerged roughly in the late 1970s as a sub-field of philosophyPhilosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...
. The naming of the field was preceded by the appearance of a number of textbooks that rejected the symbolic approach to logic
Logic
In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...
on pedagogical grounds as inappropriate and unhelpful for introductory textbooks on logic for a general audience, for example Howard Kahane
Howard Kahane
Howard Kahane was a professor of philosophy at Bernard M. Baruch College in New York. He was noted for promoting a popular, and non-mathematical, approach to logic, now known as informal logic...
’s Logic and Contemporary Rhetoric, subtitled “The Use of Reason in Everyday Life”, first published in 1971. Kahane's textbook was described on the notice of his death in the Proceedings And Addresses of the American Philosophical Association (2002) as "a text in informal logic, [that] was intended to enable students to cope with the misleading rhetoric one frequently finds in the media and in political discourse. It was organized around a discussion of fallacies, and was meant to be a practical instrument for dealing with the problems of everyday life. [It has] ... gone through many editions; [it is] ... still in print; and the thousands upon thousands of students who have taken courses in which his text [was] ... used can thank Howard for contributing to their ability to dissect arguments and avoid the deceptions of deceitful rhetoric. He tried to put into practice the ideal of discourse that aims at truth rather than merely at persuasion. (Hausman et al. 2002)" Other textbooks from the era taking this approach were Michael Scriven
Michael Scriven
Michael Scriven is a British-born academic, with a first degree in mathematics and a doctorate in philosophy. He has made significant contributions in the fields of philosophy, psychology, critical thinking, and, most notably, evaluation .He has produced over 400 scholarly publications and has...
’s Reasoning (Edgepress, 1976) and Logical Self-Defense by Ralph H. Johnson
Ralph H. Johnson
-External links:...
and J. Anthony Blair, first published in 1977. Earlier precursors in this tradition can be considered Monroe Beardsley
Monroe Beardsley
Monroe Curtis Beardsley was an American philosopher of art. He was born and raised in Bridgeport, Connecticut, and educated at Yale University , where he received the John Addison Porter Prize...
's Practical Logic (1950) and Stephen Toulmin
Stephen Toulmin
Stephen Edelston Toulmin was a British philosopher, author, and educator. Influenced by Ludwig Wittgenstein, Toulmin devoted his works to the analysis of moral reasoning. Throughout his writings, he sought to develop practical arguments which can be used effectively in evaluating the ethics behind...
's The Uses or Argument (1958).
The field perhaps became recognized under its current name with the First International Symposium on Informal Logic held in 1978. Although initially motivated by a new pedagogical approach to undergraduate logic textbooks, the scope of the field was basically defined by a list 13 of problems and issues which Blair and Johnson included as an appendix to their keynote address at this symposium:
- the theory of logical criticism
- the theory of argument
- the theory of fallacy
- the fallacy approach vs. the critical thinking approach
- the viability of the inductive/deductive dichotomy
- the ethics of argumentation and logical criticism
- the problem of assumptions and missing premises
- the problem of context
- methods of extracting arguments from context
- methods of displaying arguments
- the problem of pedagogy
- the nature, division and scope of informal logic
- the relationship of informal logic to other inquiries
David Hitchcock argues that the naming of the field was unfortunate, and that philosophy of argument would have been more appropriate. He argues that more undergraduate students in North America study informal logic than any other branch of philosophy, but that as of 2003 informal logic (or philosophy of argument) was not recognized as separate sub-field by the World Congress of Philosophy
World Congress of Philosophy
The World Congress of Philosophy is a global meeting of philosophers held every five years in a different country under the auspices of the International Federation of Philosophical Societies . First organized in 1900, these events became firmly established after the Second World War...
. Frans H. van Eemeren wrote that "informal logic" is mainly an approach to argumentation advanced by a group of US and Canadian philosophers and largely based on the previous works of Stephen Toulmin
Stephen Toulmin
Stephen Edelston Toulmin was a British philosopher, author, and educator. Influenced by Ludwig Wittgenstein, Toulmin devoted his works to the analysis of moral reasoning. Throughout his writings, he sought to develop practical arguments which can be used effectively in evaluating the ethics behind...
and to a lesser extent those of Chaïm Perelman
Chaim Perelman
Chaïm Perelman was a Polish-born philosopher of law, who studied, taught, and lived most of his life in Brussels. He was among the most important argumentation theorists of the twentieth century...
.
Alongside the symposia, since 1983 the journal Informal Logic has been the publication of record of the field, with Blair and Johnson as initial editors, with the editorial board now including two other colleagues from the University of Windsor
University of Windsor
The University of Windsor is a public comprehensive and research university in Windsor, Ontario, Canada. It is Canada's southernmost university. It has a student population of approximately 15,000 full-time and part-time undergraduate students and over 1000 graduate students...
—Christopher Tindale and Hans V. Hansen. Other journals that regularly publish articles on informal logic include Argumentation (founded in 1986), Philosophy and Rhetoric, Argumentation and Advocacy
Argumentation and Advocacy
Argumentation and Advocacy is a quarterly peer-reviewed academic journal published by the American Forensic Association, edited by Catherine H...
(the journal of the American Forensic Association
American Forensic Association
The American Forensic Association was founded in 1949 in Chicago. It took over the National Debate Tournament from the United States Military Academy in 1966...
), and Inquiry: Critical Thinking Across the Disciplines
Inquiry: Critical Thinking Across the Disciplines
Inquiry: Critical Thinking Across the Disciplines is a peer-reviewed academic journal established in 1988 by the Institute for Critical Thinking at Montclair State University...
(founded in 1988).
Proposed definitions
Johnson and Blair (2000) proposed the following definition: "Informal logic designates that branch of logic whose task is to develop non-formal2 standards, criteria, procedures for the analysis, interpretation, evaluation, critique and construction of argumentation in everyday discourse." Their meaning of non-formal2 is taken from Barth and Krabbe (1982), which is explained below.To understand the definition above, one must understand "informal" which takes its meaning in contrast to its counterpart "formal." (This point was not made for a very long time, hence the nature of informal logic remained opaque, even to those involved in it, for a period of time.) Here it is helpful to have recourse to Barth and Krabbe (1982:14f) where they distinguish three senses of the term "form." By "form1," Barth and Krabbe mean the sense of the term which derives from the Plato
Plato
Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...
nic idea of form
Theory of Forms
Plato's theory of Forms or theory of Ideas asserts that non-material abstract forms , and not the material world of change known to us through sensation, possess the highest and most fundamental kind of reality. When used in this sense, the word form is often capitalized...
—the ultimate metaphysical
Metaphysics
Metaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...
unit. Barth and Krabbe claim that most traditional logic is formal in this sense. That is, syllogistic logic is a logic of terms where the terms could naturally be understood as place-holders for Platonic (or Aristotelian
Aristotelianism
Aristotelianism is a tradition of philosophy that takes its defining inspiration from the work of Aristotle. The works of Aristotle were initially defended by the members of the Peripatetic school, and, later on, by the Neoplatonists, who produced many commentaries on Aristotle's writings...
) forms. In this first sense of "form," almost all logic is informal (not-formal). Understanding informal logic this way would be much too broad to be useful.
By "form2," Barth and Krabbe mean the form of sentences and statements as these are understood in modern systems of logic. Here validity
Validity
In logic, argument is valid if and only if its conclusion is entailed by its premises, a formula is valid if and only if it is true under every interpretation, and an argument form is valid if and only if every argument of that logical form is valid....
is the focus: if the premise
Premise
Premise can refer to:* Premise, a claim that is a reason for, or an objection against, some other claim as part of an argument...
s are false, the conclusion must then also be true. Now validity has to do with the logical form
Logical form
In logic, the logical form of a sentence or set of sentences is the form obtained by abstracting from the subject matter of its content terms or by regarding the content terms as mere placeholders or blanks on a form...
of the statement that makes up the argument. In this sense of "formal," most modern and contemporary logic is "formal." That is, such logics canonize the notion of logical form, and the notion of validity plays the central normative role. In this second sense of form, informal logic is not-formal, because it abandons the notion of logical form as the key to understanding the structure
Structure (mathematical logic)
In universal algebra and in model theory, a structure consists of a set along with a collection of finitary operations and relations which are defined on it....
of arguments, and likewise retires validity as normative for the purposes of the evaluation of argument. It seems to many that validity is too stringent a requirement, that there are good arguments in which the conclusion is supported by the premises even though it does not follow necessarily from them (as validity requires). An argument in which the conclusion is thought to be "beyond reasonable doubt, given the premises" is sufficient in law to cause a person to be sentenced to death
Capital punishment
Capital punishment, the death penalty, or execution is the sentence of death upon a person by the state as a punishment for an offence. Crimes that can result in a death penalty are known as capital crimes or capital offences. The term capital originates from the Latin capitalis, literally...
, even though it does not meet the standard of logical validity. This type of argument, based on accumulation of evidence rather than pure deduction
Deduction
Deduction may refer to:in logic:* Deductive reasoning, inference in which the conclusion is of no greater generality than the premises...
, is called a conductive argument.
By "form3," Barth and Krabbe mean to refer to "procedures which are somehow regulated or regimented, which take place according to some set of rules." Barth and Krabbe say that "we do not defend formality3 of all kinds and under all circumstances." Rather "we defend the thesis that verbal dialectic
Dialectic
Dialectic is a method of argument for resolving disagreement that has been central to Indic and European philosophy since antiquity. The word dialectic originated in Ancient Greece, and was made popular by Plato in the Socratic dialogues...
s must have a certain form (i.e., must proceed according to certain rules) in order that one can speak of the discussion as being won or lost" (19). In this third sense of "form", informal logic can be formal, for there is nothing in the informal logic enterprise that stands opposed to the idea that argumentative discourse
Discourse
Discourse generally refers to "written or spoken communication". The following are three more specific definitions:...
should be subject to norms, i.e., subject to rules, criteria, standards or procedures. Informal logic does present standards for the evaluation of argument, procedures for detecting missing premises etc.
Johnson and Blair (2000) noticed a limitation of their own definition, particularly with respect to "everyday discourse", which could indicate that it does not seek to understand specialized, domain-specific arguments made in natural languages. Consequently, they have argued that the crucial divide is between arguments made in formal language
Formal language
A formal language is a set of words—that is, finite strings of letters, symbols, or tokens that are defined in the language. The set from which these letters are taken is the alphabet over which the language is defined. A formal language is often defined by means of a formal grammar...
s and those made in natural language
Natural language
In the philosophy of language, a natural language is any language which arises in an unpremeditated fashion as the result of the innate facility for language possessed by the human intellect. A natural language is typically used for communication, and may be spoken, signed, or written...
s.
Fisher and Scriven (1997) proposed a more encompassing definition, seeing informal logic as "the discipline which studies the practice of critical thinking and provides its intellectual spine". By "critical thinking" they understand "skilled and active interpretation and evaluation of observations and communications, information and argumentation."
Criticism
Some hold the view that informal logic is not a branch or subdiscipline of logic, or even the view that there cannot be such a thing as informal logic. Massey criticizes informal logic on the grounds that it has no theory underpinning it. Informal logic, he says, requires detailed classification schemes to organize it, which in other disciplines is provided by the underlying theory. He maintains that there is no method of establishing the invalidityValidity
In logic, argument is valid if and only if its conclusion is entailed by its premises, a formula is valid if and only if it is true under every interpretation, and an argument form is valid if and only if every argument of that logical form is valid....
of an argument aside from the formal method, and that the study of fallacies may be of more interest to other disciplines, like psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
, than to philosophy and logic.
Relation to critical thinking
Since the 1980s, informal logic has been partnered and even equated, in the minds of many, with critical thinking. The precise definition of "critical thinkingCritical thinking
Critical thinking is the process or method of thinking that questions assumptions. It is a way of deciding whether a claim is true, false, or sometimes true and sometimes false, or partly true and partly false. The origins of critical thinking can be traced in Western thought to the Socratic...
" is a subject of much dispute. Critical thinking, as defined by Johnson, is the evaluation of an intellectual product (an argument, an explanation, a theory) in terms of its strengths and weaknesses. While critical thinking will include evaluation of arguments and hence require skills of argumentation including informal logic, critical thinking requires additional abilities not supplied by informal logic, such as the ability to obtain and assess information and to clarify meaning. Also, many believe that critical thinking requires certain dispositions. Understood in this way, "critical thinking" is a broad term for the attitudes and skills that are involved in analyzing and evaluating arguments. The critical thinking movement promotes critical thinking as an educational ideal. The movement emerged with great force in the 80s in North America as part of an ongoing critique of education as regards the thinking skills not being taught.
Relation to argumentation theory
The social, communicative practice of argumentation can and should be distinguished from implication (or entailmentEntailment
In logic, entailment is a relation between a set of sentences and a sentence. Let Γ be a set of one or more sentences; let S1 be the conjunction of the elements of Γ, and let S2 be a sentence: then, Γ entails S2 if and only if S1 and not-S2 are logically inconsistent...
)—a relationship between propositions; and from inference—a mental activity typically thought of as the drawing of a conclusion from premises. Informal logic may thus be said to be a logic of argumentation, as distinguished from implication and inference.
Argumentation theory (or the theory of argumentation) has come to be the term that designates the theoretical study of argumentation. This study is interdisciplinary in the sense that no one discipline will be able to provide a complete account. A full appreciation of argumentation requires insights from logic (both formal and informal), rhetoric, communication theory, linguistics, psychology, and, increasingly, computer science. Since the 1970s, there has been significant agreement that there are three basic approaches to argumentation theory: the logical, the rhetorical and the dialectical. According to Wenzel, the logical approach deals with the product, the dialectical with the process, and the rhetorical with the procedure. Thus, informal logic is one contributor to this inquiry, being most especially concerned with the norms of argument.
See also
- Argument map
- Informal fallacyInformal fallacyAn informal fallacy is an argument whose stated premises fail to support their proposed conclusion. The deviation in an informal fallacy often stems from a flaw in the path of reasoning that links the premises to the conclusion...
- Inference objectionInference objectionIn informal logic, an inference objection is an objection to an argument based not on any of its stated premises, but rather on the relationship between premise and contention. For a given simple argument, if the assumption is made that its premises are correct, fault may be found in the...
- LemmaLemma (logic)In informal logic and argument mapping, a lemma is simultaneously a contention for premises below it and a premise for a contention above it....
- Philosophy of languagePhilosophy of languagePhilosophy of language is the reasoned inquiry into the nature, origins, and usage of language. As a topic, the philosophy of language for analytic philosophers is concerned with four central problems: the nature of meaning, language use, language cognition, and the relationship between language...
- SemanticsSemanticsSemantics is the study of meaning. It focuses on the relation between signifiers, such as words, phrases, signs and symbols, and what they stand for, their denotata....
Special journal issue
The open accessOpen access journal
Open access journals are scholarly journals that are available online to the reader "without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself." Some are subsidized, and some require payment on behalf of the author.Subsidized journals...
issue 20(2) of Informal Logic from year 2000 groups a number of papers addressing foundational issues, based on the Panel on Informal Logic that was held at the 1998 World Congress of Philosophy, including:
- Hitchcock, D. (2000) The significance of informal logic for philosophy. Informal Logic 20(2), 129-138.
- Johnson, R. H. & Blair, J. A. (2000). Informal logic: An overview. Informal Logic 20(2): 93-99.
- Woods, J. (2000). How Philosophical is Informal Logic? Informal Logic 20(2): 139-167. 2000
Textbooks
- Kahane, H. (1971). Logic and contemporary rhetoric:The use of reasoning in everyday life. Belmont: Wadsworth. Still in print as
- Scriven, M. (1976). Reasoning. New York. McGraw Hill.
- Johnson, R. H. & Blair, J. A. (1977). Logical self-defense. Toronto: McGraw-Hill Ryerson. US Edition. (2006). New York: Idebate Press.
- Fogelin, R.J. (1978). Understanding arguments: An introduction to informal logic. New York: Harcourt, Brace, Jovanovich. Still in print as
- Woods, John, Andrew Irvine and Douglas Walton, 2004. Argument: Critical Thinking, Logic and the Fallacies. Toronto: Prentice Hall
- Groarke, Leo and Christopher Tindale, 2004. Good Reasoning Matters! (3rd edition). Toronto: Oxford University Press