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=                           Informal logic                           =
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                            Introduction
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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 a matter 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."


                              History
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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 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 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 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. 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).


                        Proposed definitions
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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 Platonic 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 premises are true, 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 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 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 languages 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
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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 invalidity 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.


                   Relation to critical thinking
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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" 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
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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, 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
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*Argument
*Argumentation theory
*Argument map
*Critical reasoning
*Informal fallacy
*Informal inferential reasoning
*Inference objection
*Lemma
*Philosophy of language
*Semantics


                             References
======================================================================
*Barth, E. M., &  Krabbe, E. C. W. (Eds.). (1982).
[https://books.google.com/books?id=N7NICjuErWIC&printsec=frontcover#v=onepag
e&q=informal&f=false
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). [http://psycnet.apa.org/record/1986-98688-001 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/
* [http://www.humanities.mcmaster.ca/~hitchckd/informal.pdf 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 access
[http://www.phaenex.uwindsor.ca/ojs/leddy/index.php/informal_logic/issue/view/27
7
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
*
*


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