Informal logic encompasses the principles of
logic
Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premis ...
and logical thought outside of a
formal
Formal, formality, informal or informality imply the complying with, or not complying with, some set of requirements (forms, in Ancient Greek). They may refer to:
Dress code and events
* Formal wear, attire for formal events
* Semi-formal attire ...
setting (characterized by the usage of particular
statements). However, the precise definition of "informal logic" is a matter of some dispute.
Ralph H. Johnson
Ralph Henry Johnson (January 11, 1949 – March 5, 1968) was a United States Marine who posthumously received the Medal of Honor for heroism in March 1968 during the Vietnam War. When a hand grenade was thrown into his fighting hole, he immediatel ...
and
J. Anthony Blair
John Anthony Blair (born 12 August 1941) is a Canadian philosopher.
Along with his colleague Ralph Johnson, he has been credited as one of the founding members of the informal logic movement in North America. The two co-published one of the mov ...
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."
[Johnson, Ralph H., and Blair, J. Anthony (1987), "The Current State of Informal Logic", ''Informal Logic'', 9(2–3), 147–151. Johnson & Blair added "... in everyday discourse" but in (2000), modified their definition, and broadened the focus now to include the sorts of argument that occurs not just in everyday discourse but also disciplined inquiry—what Weinstein (1990) calls "stylized discourse."] 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 is the analysis of available facts, evidence, observations, and arguments to form a judgement. The subject is complex; several different definitions exist, which generally include the rational, skeptical, and unbiased an ...
, the thinking skills movement and the interdisciplinary inquiry known as
argumentation theory.
Frans H. van Eemeren
Frans Hendrik van Eemeren (born 7 April 1946, Helmond) is a Dutch scholar, professor in the Department of Speech Communication, Argumentation Theory and Rhetoric at the University of Amsterdam. He is noted for his Pragma-dialectics theory, an argu ...
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
philosophy. The naming of the field was preceded by the appearance of a number of textbooks that rejected the
symbolic
Symbolic may refer to:
* Symbol, something that represents an idea, a process, or a physical entity
Mathematics, logic, and computing
* Symbolic computation, a scientific area concerned with computing with mathematical formulas
* Symbolic dynamic ...
approach to
logic
Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premis ...
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,
hatwas 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.
t has... gone through many editions;
t is... still in print; and the thousands upon thousands of students who have taken courses in which his text
as... 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 Johnson and ]J. Anthony Blair
John Anthony Blair (born 12 August 1941) is a Canadian philosopher.
Along with his colleague Ralph Johnson, he has been credited as one of the founding members of the informal logic movement in North America. The two co-published one of the mov ...
, first published in 1977.[ Earlier precursors in this tradition can be considered Monroe Beardsley's ''Practical Logic'' (1950) and Stephen Toulmin's ''The Uses of 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 of 13 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.][David Hitchcock]
Informal logic 25 years later
in ''Informal Logic at 25: Proceedings of the Windsor Conference (OSSA 2003) Frans H. van Eemeren
Frans Hendrik van Eemeren (born 7 April 1946, Helmond) is a Dutch scholar, professor in the Department of Speech Communication, Argumentation Theory and Rhetoric at the University of Amsterdam. He is noted for his Pragma-dialectics theory, an argu ...
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).
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 ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institutio ...
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
Validity or Valid may refer to:
Science/mathematics/statistics:
* Validity (logic), a property of a logical argument
* Scientific:
** Internal validity, the validity of causal inferences within scientific studies, usually based on experiments
...
is the focus: if the premises are true, the conclusion must then also be true. Now validity has to do with the logical form
In logic, logical form of a statement is a precisely-specified semantic version of that statement in a formal system. Informally, the logical form attempts to formalize a possibly ambiguous statement into a statement with a precise, unambig ...
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
Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...
, 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 dialectics 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 is a generalization of the notion of a conversation to any form of communication. Discourse is a major topic in social theory, with work spanning fields such as sociology, anthropology, continental philosophy, and discourse analysis. ...
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
In logic, mathematics, computer science, and linguistics, a formal language consists of words whose letters are taken from an alphabet and are well-formed according to a specific set of rules.
The alphabet of a formal language consists of s ...
s and those made in natural languages.
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."
Criticisms
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, 1981] 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 invalidity
Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be Cognitive disability, cognitive, Developmental disability, dev ...
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 is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries betwe ...
, 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 thinking
Critical thinking is the analysis of available facts, evidence, observations, and arguments to form a judgement. The subject is complex; several different definitions exist, which generally include the rational, skeptical, and unbiased an ...
'' is a subject of much dispute.[Johnson, 1992] 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 1980s 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 entailment)—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 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,[Wenzel (1990)] 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
* Argumentation theory
* Argument map
* Critical reasoning
* Informal fallacy
* Informal inferential reasoning
* Inference objection
*Lemma
Lemma may refer to:
Language and linguistics
* Lemma (morphology), the canonical, dictionary or citation form of a word
* Lemma (psycholinguistics), a mental abstraction of a word about to be uttered
Science and mathematics
* Lemma (botany), a ...
* Philosophy of language
* Semantics
Footnotes
References
*Barth, E. M., & Krabbe, E. C. W. (Eds.). (1982)
From axiom to dialogue: A philosophical study of logics and argumentation
Berlin: Walter De Gruyter.
*Blair, J. A & Johnson, R.H. (1980). The recent development of informal logic. In J. Anthony Blair and Ralph H. Johnson (Eds.). Informal logic: The first international symposium, (pp. 3–28). Inverness, CA: Edgepress.
*Ennis, R.H. (1987)
A taxonomy of critical thinking dispositions and abilities
In J.B. Baron and R.J. Sternberg (Eds.), Teaching critical thinking skills: Theory and practice, (pp. 9–26). New York: Freeman.
*Eemeren, F. H. van, & Grootendorst, R. (1992). Argumentation, communication and fallacies. Hillsdale, NJ: Lawrence Erlbaum Associates.
*Fisher, A. and Scriven, M. (1997). Critical thinking: Its definition and assessment. Point Reyes, CA: Edgepress
*
*Govier, T. (1987). Problems in argument analysis and evaluation. Dordrecht: Foris.
*Govier, T. (1999). The Philosophy of Argument. Newport News, VA: Vale Press.
*Groarke, L. (2006). Informal Logic. Stanford Encyclopedia of Philosophy, from http://plato.stanford.edu/entries/logic-informal/
preprint
* Johnson, R. H. (1992). The problem of defining critical thinking. In S. P. Norris (Ed.), The generalizability of critical thinking (pp. 38–53). New York: Teachers College Press. (Reprinted in Johnson (1996).)
*Johnson, R. H. (1996). The rise of informal logic. Newport News, VA: Vale Press
*Johnson, R. H. (1999). The relation between formal and informal logic. ''Argumentation'', 13(3) 265–74.
*Johnson, R. H. (2000). Manifest rationality: A pragmatic theory of argument. Mahwah, NJ: Lawrence Erlbaum Associates.
*Johnson, R. H. & Blair, J. A. (1987). The current state of informal logic. ''Informal Logic'' 9, 147–51.
*Johnson, R. H. & Blair, J. A. (1996). Informal logic and critical thinking. In F. van Eemeren, R. Grootendorst, & F. Snoeck Henkemans (Eds.), Fundamentals of argumentation theory (pp. 383–86). Mahwah, NJ: Lawrence Erlbaum Associates
*Johnson, R. H. & Blair, J. A. (2002). Informal logic and the reconfiguration of logic. In D. Gabbay, R. H. Johnson, H.-J. Ohlbach and J. Woods (Eds.). Handbook of the logic of argument and inference: The turn towards the practical (pp. 339–396). Elsivier: North Holland.
*MacFarlane, J. (2005). Logical Constants. Stanford Encyclopedia of Philosophy.
*Massey, G. (1981). The fallacy behind fallacies. ''Midwest Studies of Philosophy'', 6, 489–500.
*Munson, R. (1976). The way of words: an informal logic. Boston: Houghton Mifflin.
*Resnick, L. (1987). Education and learning to think. Washington, DC: National Academy Press..
* Walton, D. N. (1990). What is reasoning? What is an argument? ''The Journal of Philosophy'', 87, 399–419.
*Weinstein, M. (1990) Towards a research agenda for informal logic and critical thinking. ''Informal Logic'', 12, 121–143.
*Wenzel, J. 1990 Three perspectives on argumentation. In R Trapp and J Scheutz, (Eds.), Perspectives on argumentation: Essays in honour of Wayne Brockreide, 9-26 Waveland Press: Prospect Heights, IL
* Woods, J. (1980). What is informal logic? In J.A. Blair & R. H. Johnson (Eds.), Informal Logic: The First International Symposium (pp. 57–68). Point Reyes, CA: Edgepress.
Special journal issue
The open accessbr>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
*
*
*David Carl Wilson (2020) ''A Guide to Good Reasoning: Cultivating Intellectual Virtues'' (2nd edition) University of Minnesota Libraries Ebook Creative Commons Attribution-Non-Commercial 4.0 International License, at https://open.lib.umn.edu/goodreasoning/
*
External links
*
An Outline for Verbal Logic
{{Philosophical logic
Logic