## 1. History



*Puppo 2019*
 provides a recent collection of articles on the history of informal
logic and the issues it addresses. In many ways, informal logic as we
know it is a contemporary version of historical attempts to explain,
systematize, assess and teach arguing for practical purposes. 



In ancient times, the First Sophistic is a movement motivated by the
notion that one can teach the art of *logos* in a way that can
be effectively employed in public argument and debate. In the century
that follows, Aristotle's logical and rhetorical works --
notably the *Prior Analytics* and the *Rhetoric* --
provide a systematic account of logic and argument which is applicable
to an impressively broad range of real life arguments. Today, they
remain important works that inform discussions of informal logic. 



In modern times, *The Port Royal Logic* (Arnauld and Nicole
1662, originally titled *Logic or the Art of Thinking*) is an
attempt to outline a logic that can guide everyday reasoning. It is a
celebrated (and often disdained) introduction to the art of arguing
which has been published in more than fifty French editions and five
popular English translations. It understands "logic" as
"the art of directing reason aright, in obtaining the knowledge
of things, for the instruction both of ourselves and others"
(25). In keeping with this, it provides a practical account of good
and poor argument, discussing fallacies, syllogisms, definitions, and
deductive and probable reasoning, emphasizing real rather than
concocted examples of argument (see Finocchiaro 1997). 



One finds other analogues of contemporary attempts to study and teach
informal reasoning in nineteenth century textbooks on logic and
rhetoric. Richard Whately is of special note in this regard. He began
his career as a professor of political economy at Oxford, was
appointed Archbishop of Dublin, and attempted to establish a national
non-sectarian system of education, writing texts on reasoning that
could promote this cause. In many ways, Whately's
 *Elements of Logic*
 and *Elements of Rhetoric* (1826, 1830) are close analogues of
early versions of today's informal logic textbooks. 



Another important text, critical of Whately, but in the same broad
tradition is Mill's *A System of Logic*  (1882) (see
Godden 2014). It defines logic as the "art and science of
reasoning," stipulating that "to reason is simply to infer
any assertion from assertions already admitted." The end result
is a broad account of inference which is, like systems of informal
logic, designed to inform real life instances of argument. 



The first use of the term "informal logic" occurs in the
last chapter of Gilbert Ryle's book *Dilemmas* (1954). He
introduces it in an attempt to distinguish between formal logic and
the more varied, less strict, and less defined ways in which we need
to assess many of the arguments that are used in philosophical
discussion. 



In North America, the rise of informal logic as it is now understood
is tied to educational trends rooted in the 1960s -- a time of
social upheaval and protest (most notably, against the War in Vietnam)
which produced calls for an education relevant to the issues of the
day. This fueled an interest in the logic of everyday argument and the
teaching of introductory logic, which was at the time taught with
textbooks like Copi's popular *Introduction to Logic*
(1953). 



In *Logic and Contemporary Rhetoric: The Use of Reason in Everyday
Life* (1971), Kahane more fully embraced instances of real life
arguing, discussing a wide range of examples in newspapers, the mass
media, advertisements, books, and political campaigns. Other attempts
to provide a general introduction to logic -- by Carney and
Scheer (1964), Munson (1976), and Fogelin (1978) -- employed the
term "informal logic" to distinguish between formal logic
and other methods of argument analysis which lay outside of it. 



The idea that informal logic should be developed as a distinct field
of inquiry was championed by Johnson and Blair at the University of
Windsor. They published a popular textbook, *Logical
Self-Defense* (1977); organized and hosted "The First
International Symposium on Informal Logic" and edited the
proceedings (Blair and Johnson, 1980); established the *Informal
Logic Newsletter* (1978-1983); and ultimately turned the
newsletter into the journal *Informal Logic* (subtitled
"Reasoning and Argumentation in Theory and Practice"). In
this and other ways, they established informal logic as a field for
study, research and development. Their contributions (and those of
colleagues at Windsor and in Ontario and Canada) is reflected in the
notion that informal logic is a Canadian (or, more narrowly, Windsor)
school of argument (see Puppo 2019). 



Much of the discussion that has shaped the evolution of informal logic
as a field has taken place in a number of journals that have played a
major role in its development. They include *Informal Logic*,
*Argumentation*, *Philosophy and Rhetoric*,
*Argumentation and Advocacy* (formerly the *Journal of the
American Forensic Association*), *Teaching Philosophy*, and
(more recently) *Cogency* and *Argument and
Computation*. 



A key catalyst that promoted the development of informal logic was the
"Critical Thinking" Movement within education (well
described in Siegel 1988, Ennis 2011, and Blair 2021). The movement
pushed (and continues to push) for educational developments which make
the critical scrutiny of our beliefs and assumptions a fundamental
goal, highlighting the significance of reasoning, inference, argument
and critical assessment. 



In 1980, a California State University Executive Order promoted the
teaching of critical thinking and informal logic by requiring post
secondary institutions to include formal instruction in critical
thinking in their curriculum. According to the order:
"Instruction in critical thinking is to be designed to achieve
an understanding of the relationship of language to logic, which
should lead to the ability to analyze, criticize, and advocate ideas,
to reason inductively and deductively and to reach factual or
judgmental conclusions based on sound inferences drawn from
unambiguous statements of knowledge or belief" (Dumke 1980,
Executive Order 338). 



The accounts of argument that informal logic and the Critical Thinking
movement provide are tied to pedagogical attempts to teach students
and learners how to reason well. One result has been hundreds (perhaps
thousands) of introductory textbooks used to teach logic, critical
thinking, and argumentation skills to university and college students
in Canada, the United States, the United Kingdom, Italy, Poland,
Chile, and other countries. 



Textbooks in English offer many theoretical and pedagogical
innovations. Established texts include Battersby 2016 (*Is That a
Fact? A Field Guide for Evaluating Statistical and Scientific
Information*, 2nd ed.); Bowell and Kemp 2014 (*Critical
Thinking: A Concise Guide*, 4th ed.); Browne and Keeley 2018
(*Asking the Right Questions*, 12th ed.); Govier 2019 (*A
Practical Study of Argument*, 7th ed.); Groarke, Tindale and
Carozza 2021 (*Good Reasoning Matters!*, 7th ed.); Hughes,
Lavery and Doran 2014 (*Critical Thinking: An Introduction to the
Basic Skills*, 7th ed.); Seay and Nuccetelli 2012 (*How to
Think Logically*, 2nd ed.); Weston 2018 (*A Rulebook for
Arguments*, 5th ed.); and Wilson 2020 (*A Guide to Good
Reasoning: Cultivating Intellectual Virtues*, 2nd ed.). 



In Poland, Ajdukiewicz's *Pragmatic Logic* (1974) is an
introduction to an independently developed "pragmatic
logic" which shares similar goals, teaching and promoting tools
of logic as a central element of a general education. Its application
aims to ensure that students think clearly and consistently, express
their thoughts and ideas systematically and precisely, and justify
their claims with proper inferences (see Koszowy 2010). 



In part because reasoning and argument are ubiquitous and of interest
across many disciplines, informal logic has in many ways been
influenced by cognate fields which analyze argumentation in some way.
The latter include formal logic, speech communication, rhetoric,
linguistics, artificial intelligence, discourse analysis, feminism,
semiotics, cognitive psychology, and computational modelling.
Considered in this broader context, informal logic is a subfield of a
broader multi-disciplinary attempt to develop a comprehensive account
of real life arguing which is commonly called "argumentation
theory." 



Informal logic and argumentation theory have been highlighted at
numerous international conferences hosted by organizations committed
to the study of argument. Key conferences include nine Amsterdam
conferences (and a tenth conference in Zhenjiang) hosted by the
International Society for the Study of Argumentation (ISSA); twelve
Windsor conferences hosted by the Ontario Society for the Study of
Argumentation (OSSA); six Tokyo Conferences on Argumentation hosted by
the Japanese Debate Association; three meetings of the European
Conference on Argumentation (ECA); eight meetings of the International
Conference on Computational Models of Argument (hosted by COMMA), and
many workshops on issues of argumentation, dialogue, and persuasion
organized by the Polish group ArgDiaP. 


### 1.1 Formal and Informal Logic



One of the driving forces behind the early development of informal
logic was a desire for a logic which contained tools of analysis and
assessment above and beyond the standard formal methods of the day:
propositional logic, truth tables, syllogisms, the predicate calculus,
and so on. Johnson emphasizes a "dissatisfaction with formal
logic as the vehicle for teaching skill in argument evaluation and
argument formation" and a "desire to provide a complete
theory of reasoning that goes beyond formal deductive and inductive
logic" (2014, p. 11). Though Ryle never developed a detailed
account of what he meant by "informal logic," his comments
point in a similar direction. 



Philosophers and logicians teaching general courses on argument have
often managed the issues that this raises by mixing formal and
informal methods of analysis. Though the artificial examples of
argument that characterize early editions of Copi (and some other
texts that emphasize formal logic) have been roundly criticized (see
Johnson 1996 and Blair 2015), other authors more successfully meld
classical formal logic and examples of real argument. Harrison 1969 is
an example. So are the texts of Pospesel, which contain many examples
of real life reasoning which illustrate the patterns of inference
associated with propositional and syllogistic logic (Pospesel and
Marans 1978, Rodes and Pospesel 1991, and Pospesel 2002). Little 1980
develops an approach to critical thinking and decision making that
integrates propositional and syllogistic reasoning. 



Some informal logicians moved in an opposite direction, developing
versions of informal logic that were independent of formal logic,
appealing to alternative accounts of argument borrowed from or
influenced by philosophical reflection, or by other fields that study
argument (notably, rhetoric, dialectics, and speech communication).
Toulmin's *The Uses of Argument* (1958) and
Hamblin's *Fallacies* (1970) became theoretical
touchstones for those looking for an informal logic rooted outside of
formal logic. 



Even in these latter cases, systems and accounts of informal logic
shared some core notions with their formal cousins. Most
significantly, formal and informal logic assume (i) a premise,
inference, and conclusion conception of argument; (ii) the notion that
a good argument has premises which are true (or
"acceptable") and a conclusion which follows from them
(making the inference the argument depends on "valid" in
some way); and (iii) the idea that many arguments can be assessed by
treating them as instances of more generalized forms of argument
("schemes of argument" which include standard deductive
patterns of reasoning). 



Today, informal logic is "informal" rather than
"formal" primarily because it studies arguments as they
occur in natural language discourse, and not in formal languages of
the sort that characterize formal logic. The latter are notable for
their rigorously defined syntax, semantics, and grammar, and precisely
defined proof procedures. In contrast, arguments as they occur in real
life discourse are notable for their use of everyday language; for the
many different norms that apply to them in different contexts; and for
the diverse ways of making meaning (using pictures, facial
expressions, non-verbal sounds, music, etc.) that they employ. 



The emphasis that informal logic and its historical precursors place
on natural language argument is in keeping with the social and
pedagogical goals that motivate their development. The latter are best
served by an easily understood, broadly disseminated, understanding of
the difference between strong and weak instances of real life
argument. Formal methods (Venn diagrams, probability theory --
see Zenker 2013, different kinds of formal logic, etc.) can at times
support this goal, especially in analyses of particular kinds of
argument, but the overriding aim is natural language discourse guided
by the principles of successful reasoning. 


### 1.2 Argumentation Theory



Argumentation theory is a broad interdisciplinary field that studies
real life argument. Developments in argumentation theory have been
greatly influenced by formal and informal logic; pragma-dialectics
(developed by van Eemeren and Grootendorst and their Dutch or
"Amsterdam" school of argumentation); the Critical
Thinking Movement; American speech communication; rhetoric;
pragmatics; and the Polish School of Argument (which has published a
relevant
 manifesto).
 In its attempt to understand argument, argumentation theory does not
hesitate to make use of these and other related disciplines: cognitive
psychology, computational modeling, semiotics, discourse analysis, the
history of art, AI, and so on. 



Above and beyond their study of general methods of argument analysis,
argumentation theorists investigate arguments in a variety of ways: by
exploring particular aspects of arguing (e.g., onus, burden of proof,
or the norms that govern arguments in specific contexts); by analyzing
arguments from historical, social, political or feminist points of
view; by studying particular kinds of argument (e.g., those expressed
in works of art, or those that arise in specific legal contexts); and
by investigating the assumptions, conditions (philosophical,
epistemological, social, political, institutional, psychological,
educational, etc.) which give rise to disagreement, arguing and
argument in the first place. In many ways, such endeavors intersect
with informal logic. 



Theoretically, argumentation theory incorporates three approaches to
argument that have been associated with logic, rhetoric, and
dialectics since ancient times. Logic understands an argument as an
attempt to justify a conclusion, emphasizing its probative or
epistemic merit. Rhetoric treats an argument as an attempt to
persuade, emphasizing its persuasive force. Dialectics understands an
argument as an element of an exchange between interlocutors with
opposing points of view, emphasizing its place in an interaction
between arguers who argue back and forth. 



Like other forms of logic, informal logic emphasizes the epistemic
merit of an argument. That said, its development has been greatly
influenced by rhetorical and dialectical considerations, for
successful real life arguments must convince their intended audiences
(the public, scientists, the Members of Parliament, the readers of a
particular magazine, etc.) and (as Johnson 2000 emphasizes) include
answers to reasonable objections made by those with opposing points of
view. Bermejo Luque 2011 has proposed a relevant theory of argument
which aims to accommodate logical, rhetorical and dialectical points
of view. 


## 2. Systems of Informal Logic



As Hansen (2012) emphasizes, there are many different methods that
informal logicians use to analyze instances of argument. An account of
informal logic needs to make room for the different approaches this
implies, at the same time that it explains how they constitute a
shared field of inquiry. I will attempt to provide such an account by
emphasizing systems of informal logic. 



I understand an informal logic *system* to be a collection of
principles and methods designed for the analysis and assessment of
real life arguments. Considered from this point of view, informal
logic can be described as a field devoted to the creation, study and
application of systems of informal logic (or, more simply,
"informal logics") and the issues that this raises. 



The first textbook that described itself as an informal logic textbook
was Munson's *The Way of Words: An Informal Logic*
(1976). As his title emphasizes, his book aims to teach a specific
informal logic (a specific informal logic system) which outlines one
approach to the analysis and assessment of real life argument. Other
approaches and other systems are developed in other textbooks and in
scholarly discussion. 



Different systems of informal logic vary in a number of ways --
often, by incorporating formal, rhetorical, dialectical and other
methods of analysis to a greater or lesser extent. Many systems
propose unique approaches or mix methods that they borrow from other
systems. Groarke 2020 has outlined a "BLAST" approach to
the identification and definition of systems of informal logic. It
defines a specific informal logic system **I**, as **I** =
{**B**,**L**,**A**,**S**,**T**}, where:


* **B** = the theoretical background that informs **I**,
  

**L** = the language used to express the arguments **I**
analyzes,
  

**A** = a concept of argument,
  

**S** = a way to "standardize" arguments, and
  

**T** = tools and methods for testing the strength of arguments
evaluated using **I**.



As I show below, a particular system of informal logic can be defined
by outlining and explaining each of its five BLAST elements. When they
have been defined, different systems of informal logic and the
elements they contain can be more precisely compared, contrasted, and
evaluated. Historical precursors to present day informal logic can be
investigated from a similar point of view. 


### 2.1 A Concept of Argument (**A**)



In many ways, the third element in the BLAST list -- a concept of
argument (**A**) -- is the root of all informal logics. In
ordinary discourse, the word "argue" can mean "to
disagree," usually with the further implication that someone
does so aggressively. Informal logics, like other logics, assume a
narrower conception of argument (so called "argument-1"),
which understands an argument as an attempt to resolve disagreement
(or potential disagreement) by providing *reasons* for
accepting the point of view that it advances. 



This notion of argument is "evidentiary" in the sense that
it understands an argument as an attempt to provide evidence in
support of some conclusion. The *premises* in the argument
convey the evidence which provides those who consider the argument
reasons for accepting the conclusion. As Hitchcock 2007 puts it, an
argument is "a claim-reason complex" consisting of (1)
premises, (2) a conclusion, and (3) an inference from the premises to
the conclusion (and the implied claim that the conclusion is true,
likely true, plausible or should in some other way be accepted). 



The following sentence, taken from an article in the *Houston
Chronicle* (Devra Gartenstein 28/01/19) is a simple example of
argument in this sense. 



> 
> 
> EXAMPLE 1: Small businesses are important because they provide
> opportunities for entrepreneurs and create meaningful jobs with
> greater job satisfaction than positions with larger, traditional
> companies.
> 
> 
> 



In this example, the word "because" is an inference
indicator. It tells us that the initial statement in the sentence
("Small businesses are important") is a conclusion backed
by a premise (that small businesses "provide
opportunities...") that provides a reason for believing it to be
true. 



The example below is taken from an opinion piece (in the *Western
Courier* 25/10/08) which criticizes conservative groups opposed to
research using human embryos. 



> 
> EXAMPLE 2: This [opposition to embryonic research] is shortsighted and
> stubborn. The fact is, fetuses are being aborted whether conservatives
> like it or not. Post-abortion, the embryos are literally being thrown
> away when they could be used in lifesaving medical research.... Lives
> could be saved and vastly improved if only scientists were allowed to
> use embryos that are otherwise being tossed in the garbage.
> 



We can summarize the elements of this argument as follows. 



> 
> *Premise*: Fetuses are being aborted anyway (whether
> conservatives like it or not).
>   
> 
> *Premise*: Lives could be saved and vastly improved if
> scientists were allowed to use embryos that are otherwise being tossed
> in the garbage.
>   
> 
> *Conclusion*: The conservative opposition to embryonic research
> is shortsighted and stubborn.
> 



This is another example of a simple argument. In real life arguing,
complex arguments may contain tens (or even hundreds) of premises, and
are usually made up of layers of inference that proceed from initial
premises to intermediate conclusions which function as premises for
further conclusions, culminating in a "main" or
"principal" conclusion. 



All systems of informal logic are attempts to understand and assess
arguments in the premise/conclusion sense. In view of this, the core
value of **A** in the BLAST definition is shared by all informal
logics, though there are many variations that occur when informal
logicians expand this conception by adding other elements to it. This
can be done by understanding an argument as a premise-conclusion
complex which is directed at an *audience*, or backed by a
*warrant*, or provided as an answer to an *opponent* who
has an opposing point of view. When they expand the definition of
argument in these ways, systems of informal logic make an audience,
warrant, and/or dialectical context an essential element of a case of
argument. 


### 2.2 Theoretical Background (**B**)



Other elements recognized in the BLAST definition are notable for the
extent to which they vary from one informal logic to another. The
different theoretical backgrounds that inform different systems of
informal logic (**B** in the BLAST definition) are of special note,
for they reflect the extent to which the development of informal logic
has been a *search* for new and novel methods of analysis that
can be applied to real life arguing. In a particular case, this search
may end in Aristotle, in feminist theories of argument, in rhetoric,
in dialogue theory, in speech communication, in formal logic, or in
some combination of these and/or other theoretical points of view.




The theoretical background that characterizes systems of informal
logic can be used to identify, not only specific systems, but also
families of systems which share key theoretical elements. Many
informal logicians have, to take one example, turned to fallacy theory
in their attempt to find a logic that can account for real life
arguing. In some cases, the result has been fallacy oriented textbooks
which introduce tens or hundreds of fallacies used to dismiss straw
man reasoning, hasty generalizations, slippery slope reasoning, and so
on (see, e.g., Bennett 2018). 



Systems of informal logic that adopt a fallacy approach can be
summarized as instances of **I** in which **I** = {**B**,
**L**, **A**, **S**, **T**}, where: **B** = Fallacy
Theory, and **T** = a set of fallacies used to judge instances of
argument. An even narrower set of ("Hamblin") systems can
be defined as systems in which **B** = Hamblin. This is a family of
systems which is rooted in the account of fallacies proposed in
Hamblin 1970. 



Systems of informal logic that combine fallacy theory with other
methods of testing arguments can be understood as systems which define
**T** in a way that includes a specific a set of fallacies along
with other criteria for argument evaluation (e.g., Johnson and
Blair's ARS criteria). 


### 2.3 Language (**NL** and **NL+**)



One key element of informal logic is its focus on arguments as they
occur within natural rather than formal languages. 



Initially, informal logic texts defined natural language arguments as
verbal arguments: i.e. as arguments expressed and conveyed in words
associated with some established natural language. This is an
important focus given that arguments of this sort are a staple in the
kinds of arguing that informal logic emphasizes -- in letters to
the editor; parliamentary debate; court proceedings; and in essays and
books written in defense of some point of view (that humans could
colonize Mars, President Trump was misunderstood, socialism is the
best political system, and so on). 



When a system of informal logic is designed to analyze and assess
verbal arguments of this sort, the language of argument they assume
(**L** in the BLAST definition) consists of the words and sentences
(and the rules governing them) associated with some natural language
("**NL**"). This makes the language of argument a
complex and nuanced system of meaning which expands the possibilities
of argument beyond the "informative" statements of fact
that authors like Copi took to be the only legitimate realm of
argument. One notable feature of the expanded realm that informal
logic studies is the extent to which metaphor and other figures of
speech are used to support conclusions -- something that must be
accounted for in a comprehensive account of informal reasoning. 



As the scope of informal logic has expanded to provide a more
comprehensive account of ordinary argument, this verbal paradigm has
frequently been expanded to make room for real life arguments which
depend on non-verbal elements. Paradigm examples of these non-verbal
elements are photographs, illustrations, drawings, videos, etc. which
are used to provide evidence in support of some conclusion -- as when
a photograph or video is used to prove someone's identity, or
produced in court to give the court a *reason* to believe that
they were present at the scene of a crime. As Hitchcock (2002) notes,
"a poster with a giant photograph of a starving emaciated child
and the words 'make poverty history' can reasonably be
construed as an argument." 



Arguments that employ premises and/or conclusions that arguers convey
using non-verbal visual elements are commonly called
"visual" arguments. I leave for elsewhere the question
whether such arguments are visual in some deeper sense. In most cases,
they have verbal as well as visual elements and can, in view of this,
be described as arguments which are expressed as an amalgam of verbal
and non-verbal (visual) elements. 



The two photographs in EXAMPLE 3 (below), taken by the NASA Mars rover
Phoenix, were part of a visual argument proposed by the NASA
scientists who directed the Phoenix mission. The first photo provides
an initial view of a dig made by the rover; the second a view of the
same dig four Martian days (sols) later. When we look at the bottom
left hand corner of the first photograph and compare it to the bottom
left hand corner of the second photograph, we can see white crust in
the first photograph but not the second. According to the NASA
scientists, the only way to plausibly explain this change is by
understanding the crust as water ice which evaporated when the dig
exposed it to the sun. 


  


![nasa rover](mars2.jpg)

EXAMPLE 3




We can summarize the argument as follows.



> 
> EXAMPLE 3:
>   
> 
> *(Visual) Premise*: What we see in the bottom left hand corner
> of the first photograph of the dig.
>   
> 
> *(Visual) Premise*: What we see in the bottom left hand corner
> of the second photograph of the dig.
>   
> 
> *(Verbal) Premise*: The most plausible way to explain the
> changes we see (the disappearance of the white crust) is by
> understanding it as water ice.
>   
> 
> *Conclusion*: There is water on the planet Mars.
> 



This argument can be described as visual and verbal. Visual because
our looking at the photographs and *seeing* the difference
between them is a non-verbal component of the argument that provides
key evidence that supports the conclusion. At the same time the
argument is verbal because it contains a key verbal component provided
by the scientists' explanation of what we must be seeing. The
conclusion is established by combining these visual and verbal
components. 



When a system of informal logic recognizes visual arguments of this
sort, the value of **L** in its BLAST definition can be understood
as **NL+**, where the **+** indicates that the language of
argument includes words *and* non-verbal elements like
photographs and other non-verbal visual images. 



One might compare the expansion of informal logic to account for
visual arguments to the attempt to expand the language of formal logic
(and, some argue, the notion of argument it embraces) to allow visual
deductions (see Barwise and Etchemendy 1998). Visual premises can be
used in geometric proofs, in legal arguments (to proving that someone
committed a crime, that the murder was heinous, etc.), in reasoning
about planets, stars and black holes, and in aesthetic criticism and
evaluation. In ornithology, a well authenticated, clear photograph of
a rare species (say, the Ivory Billed Woodpecker) is widely accepted
as the proper proof that the species is not extinct. 



In other cases, a visual image may serve as a conclusion which is
backed by visual and/or verbal premises. A forensic artist concludes
that their drawing of a suspect correctly depicts what they look like
by inferring this from verbal and visual evidence which is provided by
the witnesses they interview. 



Kjeldsen 2015
 has provided a comprehensive overview of the study of visual
arguments. Informal logics that recognize visual arguments do so for
the same reason that they recognize verbal arguments: in order to
account for the kinds of arguing that play an important role in real
life discourse and exchange. Visual arguments are increasingly
significant at a time when digital communication facilitates the
creation and distribution of visual images, enhancing and increasing
the use of arguments which employ photographs, videos, art, political
cartoons, virtual reality, 3D modeling and other kinds of visuals (see
Godden, Palczewski, and Groarke, 2016). 



As is the case with words, the images used in visual arguments may, as
Kjeldsen and other rhetoricians point out, not be intended as literal
depictions of something they represent, but function as visual
metaphors which characterize some situation in an argumentatively
charged way. 



The cartoon of Napoleon III below (EXAMPLE 4) appeared in
*Punch* on Feb. 19, 1859. 



![Political cartoon of a porcupine with the face, hands, and boots of a man. The porcupine/man is saying, 'L'Empire c'est la paix'. The caption reads, 'The French Porcupine: He may be an Inoffensive Animal, but he Don't Look like it'.](FrenchPorcupineSE.jpg)

EXAMPLE 4




This is a clever caricature, but it is something more than a simple
caricature, for the cartoonist uses a drawing of Napoleon-as-porcupine
to convey a *reason* to doubt his profession of peace. We might
summarize his point as the suggestion that Napoleon's actions --
his amassing of the armaments which encircle him like quills on a
porcupine -- are not the actions of someone committed to peace. The
dissonance between his actions and his profession of peace invites the
viewer to respond to him as they would respond to an actual porcupine
-- with caution, concern and suspicion, wary of what he might do with
his weapons (even though he has an "inoffensive" posture
and makes an inoffensive sound). 



In this case the visual image in the argument is not an attempt to
literally replicate some state of affairs. The core argument we might
extract from the cartoon can be understood as follows.



> 
> 
> *Premise*: Napoleon declares that "The Empire embodies
> peace" ("L'Empire c'est la paix").
>   
> 
> *Premise*: Napoleon has surrounded himself with many armaments.
>   
> 
> *Conclusion*: Napoleon may sound inoffensive when he says that
> "The Empire embodies peace," but his build up of armaments
> suggests we should be wary of the empire he has built.
> 
> 
> 



This is a visual argument (and the second premise a visual premise) at
least in the sense that it is conveyed visually (and not with the
words in our paraphrase). The verbal paraphrase summarizes the
argument, though the non-verbal visual elements the cartoonist uses
must be replicated if we want to exactly replicate their act of
arguing. This is especially important when such arguments are open to
contrary interpretations or have meanings that are difficult to convey
in words. 



In the case of the *Punch* cartoon, we might interpret it in a
second way by adding to our initial paraphrase, understanding the
Napoleon III-as-porcupine caricature as an allusion to another famous
"Louis" King of France: Louis XII, who ruled from 1498 to
1515. Popularly known as the "porcupine" King of France,
he adopted the animal as his royal emblem, portraying the French
kingdom as a porcupine -- an animal he chose because it was popularly
believed (to some extent now as well as then) that it could shoot its
quills, symbolizing the offensive and defensive capabilities of the
king's army. 



If we understand the cartoonist's depiction as an allusion to
Louis XII, the argument in the cartoon is plausibly assigned another
premise that reminds the viewer of the rule of Louis XII, a king who
was famous for rebuilding the French army, which he then employed in a
series of wars against his neighbors (his general strategy is
criticized by Machiavelli in *The Prince*). The additional
premise can be summarized as the suggestion that Napoleon is acting
like Louis XII did -- something which provides another reason to
be wary of him. 



In many circumstances, the visual elements of an argument (like verbal
elements in arguments which are ambiguous or vague) are open to
multiple interpretations. This raises issues of representation and
interpretation. In the Napoleon example, it is difficult to say
whether the cartoonist or his audience understood his depiction to be
a reference to Louis XII. In such circumstances, the simplest strategy
is one that identifies and evaluates all the plausible interpretations
of an argument. 



Visual metaphors are common in works of art, political propaganda, and
political cartooning. One popular motif depicts politicians with a
growing Pinocchio nose, suggesting that they are, like the childhood
hero, preposterous liars (see Tseronis and Forceville 2017). In cases
such as this, visual images can have rhetorical as well as logical
significance, allowing arguers to convey their arguments in
rhetorically powerful ways. 


### 2.4 Modes of Arguing



Informal logicians who advocate for systems of informal logic that
broaden the language of argument from **NL** to **NL+**
sometimes expand the standard notion of argument even further, beyond
verbal and visual arguments, to make room for other ways of arguing.




The role of non-verbal carriers of meaning in real life discourse
allows many different semiotic modes to contribute to informal
arguments. In view of this, some argue that a fully comprehensive
account of argument must include a "multimodal" account of
meaning which recognizes many different *modes of arguing* (see
 Groarke 2015).
 The latter may employ gestures, facial expressions, sounds of
different sorts, tastes, smells, musical notes, and a host of other
non-verbal phenomena. 



Groarke 2018, Kisicek 2018, and Eckstein 2018 have
investigated "auditory" (or "acoustic") modes
of reasoning that depend on non-verbal sounds. Examples are situations
in which the sound of a siren is pointed to as evidence that the
police are on their way, or the sound of an automobile engine (or an
irregular heart) is the basis of an inference to the conclusion that
it has a leaky valve. 



Other modes of arguing invoke the senses in other ways. In 2019, Space
Cargo Unlimited and the University of Bordeaux's wine institute
(the ISVV) sent fourteen bottles of Chateau Petrus to the
International Space Station to determine how a year in space would
affect their taste and character. A year later, the wine returned to
earth where it was analyzed. A key element of this analysis was a
blind tasting conducted by 12 professional tasters who compared the
wine from space to bottles of the same vintage which had remained on
earth. The sommeliers concluded that the wine which had been in space
had a different, distinct ("more evolved") taste,
inferring their conclusion from their two tastings (which functioned
as 'taste premises'). 



Here is another example from a wine tasting. 



> 
> EXAMPLE 5:
>   
> 
> 
> A wine steward attempts to convince a customer that Napa Valley
> "Frogs Leap PS 2015" is an exceptional Petite Syrah by
> quoting high praise in a wine guide, and by handing them a glass,
> inviting them to taste it. 
> 
> 
> 



In this case, the steward provides evidence for their claim that Frogs
Leap PS 2015 is an exceptional Petite Syrah in two ways: (i) via a
verbal premise that cites the authority of a wine guide, and (ii) via
a taste test that aims to support this conclusion. In the first case,
the result is a verbal appeal to authority, in the second an argument
by taste. 



In real life arguing different modes are often mixed. In the case of
verbal arguments, the meaning of oral arguments is often notable for
its dependence on the sound of the human voice -- which can
convey meaning above and beyond that implied by words. As Gilbert
(1997) notes, uttering the sentence "Fine, fine, you're
right, I'm wrong, we'll do it your way," "can
indicate agreement with what has been said if presented flatly and
intended sincerely, or, if accompanied by an expression of anger, can
mean that the respondent does not agree at all, but is
capitulating." (pp. 2-3) Kisicek 2014 has
highlighted the important role that the paralinguistic features of
oral arguments play in many instances of verbal argument. 



Gilbert 1997 was the first informal logician to suggest that there are
different modes of arguing that need to be distinguished. His
"multi-modal" theory of "coalescent" argument
accepts the traditional conception of argument as one mode, adding to
it "emotional," "visceral" (physical) and
"kisceral" (intuitive) modes of arguing. He pairs this
with a very broad account of arguing which understands it as an
attempt to resolve conflicting attitudes, beliefs, feelings and
intuitions in a way that brings about the "coalescence" of
competing points of view. 



According to Gilbert's account, an argument may consist of
sentences and/or expressions of emotion, physical demonstrations and
difficult to define intuitions. This allows a forlorn look or tears to
count as premises in an argument insofar as they provide evidence that
promotes coalescence (and inference in this broad sense). As Gilbert
argues, his non-traditional modes of arguing may, in real life
situations, provide effective ways of resolving the disagreement that
gives rise to argument. 



Gilbert's account of modes radically expands our understanding
of argument beyond "language" as it is traditionally
conceived. In an account of the "anthropology" of
argument, Tindale 2021 defends the alternative "logics"
this makes possible. In doing so, he promotes informal logics that
recognize verbal arguments (and in this sense **L**) but add to it
a much broader range of everyday communication which can convey the
substance of an argument via expressions of emotion, physical actions
(including non-verbal means of communication like so called
"body language"), and difficult to define intuitions. This
expands the language of argument far beyond words and sentences, in a
way that maximizes the breadth of **L+**. 


## 3. Standardizing Arguments



The ultimate goal of informal logic is normative: i.e. systems of
logic that provide us with tools that can be used to evaluate real
life arguments and the key components they contain. Because real life
discourse often fails to present the latter clearly, most systems of
informal logic prepare the way for argument evaluation by explicitly
identifying an argument's premises, conclusions, and inferences.
The process of doing so is commonly called "standardizing"
(**S** in the BLAST definition). 



In the process of standardization, informal logics aim to untangle
issues that obscure the structure and content of real life arguments.
Arguments in ordinary discourse are, for example, frequently vague,
ambiguous or in other ways unclear. Premises and conclusions can be
conveyed by rhetorical questions ("Can anyone seriously
believe...?" "Could the defendant have been in two places
at once?") and the key components of an argument may be
interspersed with irrelevant digressions and repetition. When we
extract an argument from the context in which it occurs, it can be
important to recognize what is implicit but relevant at the same time
that we discard what is explicit but irrelevant. 



Standardizing clarifies the structure of an argument in ordinary
discourse by: 


* discarding irrelevant and distracting digressions, repetition, and
remarks ("noise") which do not play a role in the
reasoning the argument contains;
* restating the content of rhetorical questions and other stylistic
devices that may obscure the meaning of the argument's
components;
* clarifying incomplete, vague or ambiguous claims and utterances;
and/or
* recognizing components of the argument which are not explicitly
expressed.



Systems of informal logic may standardize arguments in a variety of
ways. In its simplest form, a standardized argument is a list of
premises and a conclusion (the argument's inference is the
implicit move from the premises to the conclusion). EXAMPLE 1 above
can be standardized as follows.



> 
> 
> EXAMPLE 1: Small businesses are important because they provide
> opportunities for entrepreneurs and create meaningful jobs with
> greater job satisfaction than positions with larger, traditional
> companies. 
> 
> 
> 



> 
> 
> *Premise*: [Small businesses] provide opportunities for
> entrepreneurs and create meaningful jobs with greater job satisfaction
> than positions with larger, traditional companies. *Conclusion*:
> Small businesses are important. 
> 
> 
> 



In this example, the word "because" functions as an
"inference indicator" which tells us that the claim that
follows is a premise offered in support of the conclusion which
precedes it. In other cases, words like "for,"
"given that," "since," are ways of introducing
premises, while words like "so," "hence,"
"thus," "therefore," are used to introduce
conclusions. 



Verbal inference indicators are an important, but not necessary or
sufficient, sign of argument. For indicator words can be used in other
ways ("because" may indicate an explanation rather than an
argument, a causal connection, emphasis of some sort, a temporal
order, etc.), and are not necessary when a context makes it clear that
someone is providing reasons for a conclusion. 


### 3.1 Implicit Premises and Conclusions



One issue that is frequently addressed in standardization is an
argument's dependence on premises and conclusions which are
assumed but not explicitly stated. 



The following report from the New Hampshire *Rockingham News*
(30/8/2002) comments on a court case which sent the organizer of dog
fights to jail for cruelty to animals. 



> 
> 
> EXAMPLE 6: A co-ordinator for the Humane Society supported a prison
> sentence, claiming that the minor penalties normally associated with
> misdemeanor convictions are not a sufficient deterrent in this
> case.
> 
> 
> 



We can standardize the co-ordinator's argument as follows.



> 
> 
> *Premise*: The minor penalties normally associated with
> misdemeanor convictions are not a sufficient deterrent in this case.
>   
> 
> *Implicit Premise 1*: Penalties for crimes should have a
> deterrent effect.
>   
> 
> *Implicit Premise 2*: Prison is a sufficient deterrent.
>   
> 
> *Conclusion*: A prison sentence, but not the minor penalties
> normally associated with misdemeanor convictions, is appropriate. 
> 
> 
> 



It is important to recognize the assumption which is rendered as
*Implicit Premise 1* (which is, in Toulmin's words,
"a warrant") for it is a claim that the argument depends
on when the arguer concludes that the penalties normally associated
with misdemeanors are not a sufficient deterrent in this case. The
remaining part of the conclusion -- the suggestion that a prison
sentence is appropriate -- depends on *Implicit Premise
2*, which recognizes the further assumption that this will have a
deterrent effect. 



Recognizing the argument's implicit premises prepares the way
for argument evaluation, for they, like the argument's explicit
premise, need to be evaluated when the argument is assessed. If we
reject the implicit premises (by, e.g., arguing that the goal of
criminal penalties should be retribution, not deterrence), then the
argument fails to provide convincing evidence for its conclusion. 



Arguments with implicit premises or conclusions are recognized in
ancient discussions of *enthymemes*: syllogisms with unstated
premises. A contemporary example is American Vice-President Dick
Cheney's defense of the Bush administration's decision not
to try foreigners charged with terrorism offenses as prisoners of war
(something that would guarantee legal protections for those accused of
terrorism). 



> 
> EXAMPLE 7 (from a report in the *New York Times*, 15/11/2001):
>   
> 
> "The basic proposition here is that somebody who comes into the
> United States of America illegally ... is not a lawful combatant....
> They don't [therefore] deserve to be treated as a prisoner of
> war."
> 



We can standardize the argument as: 



> 
> EXAMPLE 8:
>   
> 
> *Premise*: Somebody who comes into the United States of America
> illegally ... is not a lawful combatant.
>   
> 
> *Implicit Premise*: Someone who is not a lawful combatant
> doesn't deserve to be treated as a prisoner of war.
>   
> 
> *Conclusion*: They don't deserve to be treated as a
> prisoner of war.
>   
> 
> 



As in many other cases, the argument's implicit premise
identifies the link that ties the explicit premise to the conclusion.
When we evaluate the argument, it raises a number of questions. How
should a "lawful combatant" be defined? Why are combatants
who illegally enter a country for the purpose of war (in undertaking
surveillance or going behind enemy lines) widely recognized as
prisoners of war? What are our moral obligations to combatants, lawful
and unlawful? 



In other enthymemes, the conclusion of an argument may be unstated. In
a debate over the question whether witnesses to a crime can be
trusted, an arguer might state: "*They* are friends of
the accused, and no friends of the accused can be trusted." Such
claims clearly suggest that "*They* cannot be
trusted," a claim that needs to be recognized as an implicit
conclusion in an attempt to standardize and evaluate the argument.




As in the case of verbal arguments, implicit premises and conclusions
play an important role in many visual and multimodal arguments. In
EXAMPLE 9 (below), the title "Just Add Vodka" is
superimposed over a gigantic bottle of vodka pouring its contents on
the scene below. Outside the vodka splash, one sees a sleepy hamlet.
Inside the vodka splash, it is transformed into a bustling cityscape
which boasts skyscrapers and a nightlife with lights, people,
nightclubs, bars, and restaurants. 



![vodka print ad](vodka.jpg)

EXAMPLE 9




The image in this advertisement is a visual metaphor which suggests
that vodka can transform one's life in the way that it
transforms the scene in the advertisement, turning the (dreary) life
one lives in a sleepy hamlet into the kind of exciting nightlife one
finds in a cosmopolitan urban center. Insofar as this message is
featured in an advertisement, we can plausibly understand this message
as a proposed *reason* to buy the vodka in question. 



We might standardize the argument this implies as follows. 



> 
> EXAMPLE 9:
>   
> 
> *(Visual) Premise*: If you drink our vodka, it can transform
> your night life in the way it transforms the village in the
> photograph: into an exciting major city.
>   
> 
> *Implicit Premise*: A life of urban excitement is preferable to
> the quiet life of a village.
>   
> 
> *Conclusion*: You should "Just Add Vodka" to your
> life.
> 



I have summarized the first premise in the argument in a way that
refers to the image because it is difficult to fully capture the
(almost magical) transformation the advertisement promises if we try
to translate it into words. The implicit premise in the
standardization is a key part of the argument because it is a key
assumption made in the move from the (visually) explicit premise to
the conclusion. So understood the argument can be analyzed and
evaluated as an argument which has a questionable explicit and
implicit premise (and an inference which is an instance of the fallacy
"Affirming the Consequent"). 



The attempt to identify implicit premises or conclusions in an
argument can raise some significant theoretical questions when it is
standardized. All arguments rely on many assumptions, raising the
question whether and when and how they should be recognized. In cases
in which it is clear that an unstated premise or conclusion needs to
be recognized, it can often be interpreted in different ways. 



One principle that many systems of informal logic use to choose
between alternative interpretations of implicit argument components is
the "Principle of Charity." It favors an interpretation of
an argument which makes it as credible as possible. In many
situations, this can best be accomplished by attributing it a
"logical minimum," understood as the weakest implicit
component needed to successfully connect the argument's premises
to its conclusion. 


### 3.2 Key Component Tables and Diagrams



Standardizing arguments by listing their premises and conclusions is
one way to delineate the content of an argument and prepare it for
evaluation. But standardizing of this sort has a major shortcoming,
for it does not distinguish between different kinds of inferences an
argument may contain. One way to address the issues that this raises
is by standardizing an argument with a table that catalogues an
argument's premises and conclusions (a Key Component or
"KC" table) and combining it with an argument diagram (a
"mapping") that depicts the structure of its inferences.




In EXAMPLE 10 (below), I have used this method to standardize an
argument that Kretzmann uses in his account of the medieval
philosopher William of Sherwood, where he concludes that it is likely
that William was a Master at the University of Paris. The first column
of the KC table lists the premises and conclusion of the argument; the
second assigns them their role as premise or conclusion; the third
lists the source from which they are derived. The diagram that follows
depicts the relationships between the argument's key components,
using arrows to indicate the inferences it includes. 



![image text](TableDiagram1.jpg)

EXAMPLE 10




This standardization shows that the Sherwood argument is supported by
three "convergent" premises which provide three
independent reasons that support the argument's conclusion in
different ways. 



In other instances of argument, two or more "linked"
premises combine to support a conclusion with a single inference. The
argument "The murderer was very strong, so George cannot be the
murderer." is an enthymeme which assumes that "George is
not very strong." Using square brackets ([ ]) to indicate this
implicit component, we can standardize the argument with the following
KC table and diagram. In this case, the linked premises are indicated
with a plus sign ("+") that connects them in the diagram.
It indicates that they support a conclusion (only) when combined. 



![image text](TableDiagram2.jpg)

EXAMPLE 11




The use of KC tables and diagrams is not limited to purely verbal
arguments. When arguments have non-verbal key components, visual and
multimodal premises and conclusions can be recognized in a key
component table by ostension, or by reproducing them in some way. Once
they are identified in a KC table, the inferences such arguments
depend on can be mapped in standard ways. 



The following table and diagram standardizes EXAMPLE 3, which contains
an inference from three linked premises (two visual and one verbal) to
the conclusion that there is water on the planet Mars. 



![image text](TableDiagram3.jpg)


KC table are not the only way to diagram the structure of real life
arguments. Diagramming (mapping) has its own history, which
incorporates many different ways of diagramming arguments. The
usefulness of diagramming is already recognized in Whately 1826 and,
in the early twentieth century, in Wigmore 1913, who develops a form
of mapping ("evidence charts") designed to portray and
analyze complex chains of judicial reasoning. 



The development of informal logic has kindled a renewed interest in
different kinds of diagrams which are supported by the development of
associated software (Rationale, Reason!Able, Araucaria, Athena,
Compendium, Theseus) and online aids (Debate Mapper, TruthMapping.Com,
Argunet, Agora). 


### 3.3 Supplemented Diagrams



KC tables and diagrams prepare the way for argument evaluation by
clarifying the internal structure and content of an argument. Other
aspects of an argument that may need to be considered in argument
assessment can be included in a "supplemented" diagram
which adds an account of the context in which it is embedded. Three
aspects of arguments merit note in this regard. 



The first is the *audience* to which an argument is addressed.
Most real life arguments are used in an attempt to convince some
intended audience of some point of view. In view of this, successful
arguments must be built with this in mind. 



A convincing argument for the conclusion that the United Nations
cannot be trusted must address different issues when it is directed at
a Chinese, Norwegian, Kenyan, Israeli, Swiss, Palestinian, etc.
audience. As rhetoric has emphasized since its beginnings, this means
that successful arguers must construct their arguments in ways that
recognize the beliefs, attitudes and values of their intended audience
(and in this sense 'speak' to them). Tindale (1999, 2004,
2010) has imported this notion into informal logic, advocating an
informal logic that incorporates an analysis of audience. 



A second contextual factor relevant to the evaluation of an argument
is the goal of the arguer. As Hitchcock 2002 points out, acts of
arguing may make a declaration ("The evidence shows that you
committed an assault, so I find you guilty as charged.");
command or make a request ("You were there, so you must tell us
what happened." "The children are shivering, so please
close the door."); make a promise ("I know it matters to
you, so I promise to go tomorrow."); express a sentiment
("What we did was inexcusable, so we beg your
forgiveness"); and function in many other ways. 



As Pinto and Gilbert have emphasized, this means that a successful
argument (which is successful in the sense that it accomplishes the
arguer's purpose in presenting the argument), may produce a
withholding of assent (or full assent) to some proposition, a
particular attitude, an emotional state like fear or hope, or a
certain kind of behavior (by, e.g., as when an argument demands that
people take up arms against a foe or take action in support of social
change). When one bargains, the goal of argument is not truth, but a
bargain that serves one's interests. As Hoffman 2016 notes, an
argument may not aim to resolve disagreement, but to promote
reflection and the raising of important questions. 



The different goals arguer's try to achieve via argument may
make their success and legitimacy turn on norms and rules that add to
(or subtract from) the traditional strictures that guide argument
evaluation. In some circumstances, it makes ultimatums, exaggerations,
threats and insults a permissible element of arguing. In sharp
contrast, they are unacceptable in attempts to determine what is true
from a scientific point of view, where such behaviors are instances of
the fallacy *ad baculum*. 



Walton 2007 accommodates the different goals associated with real life
arguments by distinguishing between different kinds of
*dialogues* in which arguing occurs. The rules for a particular
kind of dialogue define what types of argumentative moves are allowed,
what kinds of questions and responses are permitted, and what norms
arguments must adhere to. 



The seven basic types of dialogue he distinguishes can be summarized
as follows.





|  |  |  |  |
| --- | --- | --- | --- |
| **Type** | **Situation** | **Arguers' Goal** | **Dialogue Goal** |
| Persuasion | Conflict of Opinion | Persuade Other Party | Resolve Issue |
| Inquiry | Need to Have Proof | Verify Evidence | Prove Hypothesis |
| Discovery | Need for Explanation | Find a Hypothesis | Support Hypothesis |
| Negotiation | Conflict of Interests | Secure Interests | Settle Issue |
| Information | Need Information | Acquire Information | Exchange Information |
| Deliberation | Practical Choice | Fit Goals and Actions | Decide What to Do |
| Eristic | Personal Conflict | Attack an Opponent | Reveal Deep Conflict |




In dialogues of inquiry, arguments are used as tools in an attempt to
establish what is true. So understood, arguments must adhere to strict
standards that determine what counts as evidence and counter-evidence
for some point of view. In eristic dialogue, arguing is combat and the
aim is to vanquish one's opponent (and humiliate them, ideally
by wowing one's audience with one's mental gymnastics). In
doing so, sophistical tricks and fallacious reasoning are welcome if
they serve this end. 



Walton's dialogue typology leaves room for more narrowly defined
kinds of dialogue. Collective bargaining is a specific kind of
negotiation dialogue which is governed by legal rules and well
established practices that very precisely delineate what is and is not
allowed in bargaining. Different subdialogues are associated with
different norms, rules and practices. 



A third contextual factor that may warrant comment in a supplemented
diagram is the dialectical context in which an argument occurs. In his
account of argument, Johnson 2000 distinguishes between the
"illative" core of an argument and the argument's
"dialectical tier," understanding the former as a
"proto-argument" which consists of a set of premises
offered in support of some conclusion. It is the kernel of an
argument, but he considers it an argument in the full sense only if it
fully engages the dialectical tier, considering alternative points of
view, addressing objections to the conclusion it proposes. 


## 4. Testing Arguments



The ultimate goal of informal logic is normative: an account of
argument and systems of informal logic that can be used to determine
when and whether real life arguments are strong or weak, good or bad,
convincing or unconvincing. Standardizing prepares arguments for such
assessment. This makes **T** in the BLAST definition -- the
tools and methods which are used to test argument strength -- the
most important defining element in a system of informal logic. 



Almost all informal logics understand a good (strong) argument to be
an argument with "acceptable" premises and a
"valid" inference -- i.e. a conclusion that follows
from them. Hansen 2012 has argued that informal logic should follow
classical logic, and not concern itself with the assessment of premise
acceptability, but its engagement with real life arguments (and the
desire to evaluate them in a fulsome way) has produced a field that
includes this within argument evaluation. In this and in other
regards, systems of informal logic adopt many different approaches to
argument assessment. 


### 4.1 AV Criteria



In classical logic, an argument is (deductively) valid if it is
impossible for its premises to be true and its conclusion false. On
this account, the ultimate aim of arguing is a "sound"
argument: i.e. a valid argument with true premises. 



Within informal logic, the simplest criterion for good arguments is an
informal analogue of soundness. It understands a good argument to be
an argument that justifies its conclusion by providing good (strong,
credible, etc.) reasons for believing it. Within the argument, this
implies premises which are "acceptable" and a conclusion
that follows from them. We can summarize this basic criterion as
**T** = {**A**,**V**}, where **A** is an account of
premise acceptability, and **V** is an account of informal validity
which determines when a conclusion follows from premises in a way that
is approved of (deductively, inductively, conductively, and/or
abductively, etc.). 



Following Johnson and Blair (1977, 1994), many systems of informal
logic adopt an **ARS** version of these **AV** criteria, making
"Acceptability, Relevance and Sufficiency" the
requirements for good argument. On this account, premises are
acceptable when they are true or acceptable in some other way;
relevant when they provide some (i.e. any) support for the conclusion
of the argument; and sufficient when they provide enough support to
warrant its acceptance -- as likely, true, plausible, etc. 



> 
> *Premise Acceptability*
> 



Within informal arguments, premises may be acceptable in a variety of
ways. In many circumstances, they are acceptable if they are likely
true and unacceptable if likely false. 



It is worth noting that this truth criterion can be expanded to apply
to visual premises. An image functioning as a visual premise may, for
example, be evaluated as a "true" or "false"
depiction of what it represents. A photograph or an image may be
unacceptable because it is untrustworthy or categorizes a situation in
a misleading way. Photographs are often 'doctored' or in
other ways designed to present things in ways that do not accurately
reflect what is photographed. Other kinds of multimodal premises can
be understood as likely true to the extent that they are a reliable
basis for an inference. 



In some kinds of dialogue -- in the exchanges that characterize
negotiation, bargaining, eristic, and persuasion -- acceptable
premises may not need to be true. In bargaining
("haggling") a buyer may claim that "I will not give
you a penny more than $300 for that lamp" as a premise in
support of the conclusion that the seller should agree to a lower
price. This counts as an acceptable premise even if it is an idle
threat that the buyer will never carry out, for threats of this sort
are an acceptable element of the arguments that take place in this
kind of dialogue. 



In other cases, informal logics use acceptability rather than truth as
a criterion for judging premises in contexts in which it is difficult
to judge premises as true or false. In such cases, acceptable premises
may be plausible (or exploratory) hypotheses, claims that can only be
said to be generally accepted or assumed, or ethical or aesthetic
judgments which are not easily categorized as true or false. 



In still other circumstances, truth may be required for acceptability,
but only one of a number of conditions that must be satisfied. Even
when a premise is true, it may be unacceptable because it violates the
rules of interaction that govern the dialogue in which it is embedded.
In a legal proceeding or a formal hearing, premises and arguments must
not entertain premises that violate rules of procedure. 



In situations in which arguments are attempts to convince a specific
audience of a conclusion, an acceptable premise may need to be true,
but also acceptable to the members of this audience. As Aristotle
suggests in the *Rhetoric*, successful arguments may need to
have premises that are in keeping with the *pathos* of an
audience (and do so in a way that does not undermine the character
-- the *ethos* -- of the arguer). As Gilbert 1997,
2014 has emphasized, there are many real life circumstances in which
the emotional acceptability of a premise is required for argument
success. 



One of the first VR productions by the *New York Times* was
"Kiya," a production which recreated an incidence of
domestic abuse in an attempt to provide support for the importance of
attempts to address issues of domestic violence. Its producer
describes it as an attempt to use "the immersive power of
virtual reality: its ability to generate intense empathy on the part
of the viewer; to wring from the audience the intense emotional
connection that these stories deserve" (NYT, Jan 21, 2016). 



> 
> *Inference Validity*
> 



In its attempt to account for a broad range of real life arguing,
informal logics have expanded traditional notions of premise
acceptability. Something similar has happened in the case of inference
validity. The end result is an expansion of both sides of the
**AV** criteria for good argument. 



In the case of inference validity, this expansion has been
accomplished by treating deductive validity as one variant of
validity, and by recognizing other "defeasible,"
non-deductive ways in which premises may entail conclusions. Govier
1987 dubs the deductive/inductive distinction as "the great
divide," emphasizing the latter over the former. Sometimes
informal logic systems understand inductive arguments narrowly, as
inductive generalizations. Sometimes more broadly, as arguments which
have premises that imply that a conclusion is (only) probable or
plausible, leaving open the possibility that it is false. 



"Conductive" arguments support their conclusions by
accumulating non-decisive reasons in their favor. They are valid when
they collect enough reasons to warrant their conclusions. In a
particular case, different elements of evidence may suggest but not
prove that someone charged with murder is guilty but make the
conclusion likely if enough evidence of this sort is accumulated (a
witness claims he pulled the trigger, the ballistics report shows that
the bullet came from a gun he owned, he wrote an e-mail saying he
would "get" the victim, etc.). 



Strong "abductive" arguments are convincing instances of
"inference to the best explanation" (see Harman 1965).
They recognize some facts, point out that they are entailed by some
hypothesis, and conclude that the hypothesis is true. Taken at face
value, abductive arguments appear to be instances of the deductive
fallacy "affirming the consequent," but play an important
role to play in medical, scientific and legal inquiry (see Walton
2004).


### 4.2 Fallacy Theory



**AV** criteria are in many ways an extension of the notion of good
argument enshrined in classical logic. In the search for ways to deal
with real life arguments, some informal logicians have moved in a
different direction, reviving fallacy theory as an alternative.
Hamblin 1970 has become a touchstone for moves in this direction. 



Systems of informal logic that rely on fallacies test arguments by
asking whether their proponents are guilty of fallacious reasoning.
While there is no agreed-upon taxonomy of fallacies, many canonical
fallacies have been emphasized in the analysis of informal arguments.
They include formal fallacies like affirming the consequent and
denying the antecedent; and informal fallacies like *ad
hominem* ("against the person"), slippery slope,
*ad baculum* ("appeal to threat or force"), *ad
misericordiam* ("appeal to pity"), "hasty
generalization," and "two wrongs" reasoning (as in
"two wrongs don't make a right"). The systems of
informal logic taught in textbooks often add specialized variants of
the standard fallacies ("misleading vividness" designates
the misuse of vivid anecdotal evidence in hasty generalizations, and
so on.) 



Woods and Walton 1982 and Hansen and Pinto 1995 contain detailed
discussions of the definition, analysis and assessment of fallacies.
In argumentation theory, van Eemeren and Grootendorst 1992 propose a
"pragma-dialectical" account of fallacies which treats
them as violations of rules that govern critical discussion --
dialogues that attempt to resolve a difference of opinion. Battersby
and Bailin 2011 view fallacies as patterns of argument patterns
"whose persuasive power greatly exceeds its probative [i.e.
evidential] value," making fallacies errors in reasoning that
ordinary arguers are attracted to in view of their rhetorical appeal.




Some fallacies -- e.g., equivocation and begging the question
(i.e. circular reasoning) -- highlight important issues that
frequently interfere with real life arguing, but fallacy theory has
been criticized when it is adopted as a general account of argument.
The issues this raises include its unsystematic nature, disagreements
about the definition and nature of specific fallacies, and the
emphasis that fallacy theory places on faulty reasoning rather than
good argument. Hitchcock (1995, 324) writes that the idea that we
should teach reasoning by fallacies is "like saying that the
best way to teach somebody to play tennis without making the common
mistakes is to demonstrate these faults in action and get him to label
and respond to them" (see Feldman 2009). 



The theoretical issues raised by fallacy theory are compounded by
instances of traditional fallacies which have a reasonable role to
play in real life arguing. Appeals to pity and other appeals to
emotion have, to take one example, a legitimate role to play in moral,
political and aesthetic debate. The following examples highlight other
circumstances in which arguments which fit the definition of a
traditional fallacy cannot be so readily dismissed. 



> 
> 
> EXAMPLE 12:
>   
> 
> A remark from a Danish television debate over the question whether the
> Danish church should be separated from the Danish state (Jorgensen
> 1995, 369): "You should not listen to my opponent. He wants to
> sever the Danish church from the state for his own personal
> sake." This seems a classic example of *ad hominem*,
> Kahane 1995 (p. 65), describing it as a fallacy that occurs when an
> arguer attacks "his opponent rather than his opponent's
> evidence and arguments." But this is an accusation of conflict
> of interest which cannot be dismissed out of hand. If there is reason
> to believe that an arguer favors a point of view because they have
> something to gain from it (say, the purchase of a company in which
> they own shares), this does raise questions about the extent to which
> their arguments should be entertained.
> 
> 
> 
> EXAMPLE 13:
>   
> 
> Martin Luther King Jr., influenced by Gandhi, argued that one can
> justifiably break laws in a struggle for social justice. Such
> arguments play a central role in the civil rights movement. They
> cannot be summarily dismissed, though they appear to be clear cases of
> "two wrongs make a right."
> 
> 
> 
> EXAMPLE 14:
>   
> 
> The argument that "the attempt to use military force to put an
> end to terrorism is wrong because it will take us down a slippery
> slope that will end in improper interference in the affairs of
> independent states" cannot be dismissed because it is an
> instance of slippery slope reasoning. If it is true that some action
> will precipitate a chain of consequences that lead down an alleged
> slippery slope, this is a good reason to question it.
> 
> 
> 



Examples of this sort have forced careful accounts of fallacies to
make room for reasonable arguments which share the form of traditional
fallacies. 



In doing so, it is helpful to distinguish between fallacies which do
and do not have non-fallacious instances. Equivocation, *post hoc
ergo propter hoc*, *non sequitor* and hasty generalization
are commonly classified as forms of argument that are inherently
mistaken. In contrast, traditional fallacies like *ad hominem*,
two wrongs reasoning, guilt by association, and appeal to pity are
patterns of reasoning which can, when they are constructed in the
right way, play a legitimate role within real life reasoning (and are,
in view of this, sometimes treated as argument schemes rather than
fallacies). 


### 4.3 Natural Language Deductivism



Natural Language Deductivism ("NLD") is an approach to
informal reasoning that retains classical logic's focus on
deductive validity (see Groarke 1999, and
 Govier 1987,
 who develops an initial account NLD, but ultimately favors a more
radical break from classical logic). It suggests that we should
interpret informal arguments as attempts to create deductively valid
inferences which can be analyzed and assessed accordingly. In a
deductivist system of informal logic, the **V** in the **AV**
criteria for good arguments is this classical notion of validity. 



NLD has frequently been rejected on the basis of the common, but
mistaken, notion that deductively valid arguments must have certain
conclusions -- a misconception that seems founded on deductive
validity's historical connections to formal logic and
mathematics (see Groarke 1999). It is true that ordinary arguing
rarely satisfies the strict proof procedures they imply, but deductive
validity is not restricted to this compass and there are many
instances of ordinary argument which are clear examples of deductively
valid argument. 



In cases of deductive reasoning, the conclusion of an argument need
not be certain, but only as certain as the premises, creating ample room
for conclusions which are merely likely, plausible, or probable.
EXAMPLE 15 is taken from a radio commentary on population growth. 



> 
> EXAMPLE 15:
>   
> 
> The population of the world will grow from 6 to 9 billion in the next
> fifteen years so we will, if we are to provide sufficient food for
> everyone, need to find a way to provide food for an additional 3
> billion people.
> 



In this case, the premise of the argument is not certain, but
reasonably thought to be true -- because it was (in the
commentary) backed by an extrapolation from well established
population trends. The deductively valid inference based upon it makes
it reasonable to judge the conclusion of the argument true as well,
though it is not certain, as all predictions about population growth
are, at best, plausible conjectures. 



NLD's plausibility as a general theory of argument turns on its
account of arguments which are not prima facie deductive. Faced with
arguments of this sort, it preserves the deductivist approach by
attributing an implicit premise (essentially, a deductive warrant) to
such arguments in a way that deductively connects an argument's
premises to its conclusion. Typically this is an
"associated" conditional of the form "If P, then
C" where P is the argument's premises and C is its
conclusion. 



A 2015 blog by a professional dietician (Dr. Cristina Sutter)
criticizes arguments that justify the claim that garcinia cambogia is
a miracle weight loss pill by appealing to the authority of the
popular television personality "Dr. Oz." -- instances
of the reasoning "Dr. Oz Says It, So It Must Be True." We
can standardize the pattern of argument she criticizes as: 



> 
> 
> EXAMPLE 16:
>   
> 
> *Premise*: Dr. Oz says [that gracinia cambogia is a miracle
> weight loss pill].
>   
> 
> *Conclusion*: This must be true. 
> 
> 
> 



If one judges only by the explicit premise in this argument
("Dr. Oz says..."), this is not a deductively valid
argument, for it is obvious that the premise could be true and the
conclusion false: Dr. Oz could say gracinia cambogia is a miracle
weight loss pill and be wrong. That said, anyone using this argument
must assume an associated conditional which can be understood as an
implicit premise, allowing us to standardize the argument as: 



> 
> 
> *Premise*: Dr. Oz says [that gracinia cambogia is a miracle
> weight loss pill].
>   
> 
> *Implicit Premise*: If Dr. Oz says this, it must be true.
>   
> 
> *Conclusion*: This must be true. 
> 
> 
> 



So understood, the Dr. Oz argument is deductively valid, but not
sound, as it is a valid argument with a problematic implicit premise.




NLD deals with inductive generalizations in a similar way. Consider
the following example from a conversation about French men.



> 
> 
> EXAMPLE 17:
>   
> 
> "French men are fastidious about their appearance. I have worked
> with many and this was what I found." 
> 
> 
> 



In this example, the move from the premise to the conclusion of the
argument assumes that the sample of French men the arguer is familiar
with are a representative sample of French men. If this is not likely,
then the sample does not provide good reasons for concluding that
French men are, in general, as fastidious if they are. If we recognize
this assumption as an implicit premise when we standardize the
argument, then the argument is deductively valid, for a representative
sample is a subset of a population that accurately reflects the
characteristics of the larger group. 



In this way, NLD turns the uncertainty that characterizes inductive
generalizations (and other forms of informal validity) into
uncertainty that is connected to an associated conditional which
warrants the move from an argument's premises to its conclusion.
This does not eliminate such uncertainty, but maintains it as a key
consideration in argument evaluation, for it makes the status of this
warrant an essential element of premise acceptability. 



In favor of NLD, it has been argued that reconstruction of many
arguments it proposes is a dialectically useful way to make explicit
the key assumptions that arguments depend on, and frees us from the
need to distinguish between different kinds of validity in ways that
can be problematic when they are applied to real life arguing. The
pragma-dialectical account of indirect speech acts (Eemeren and
Grootendorst 2002, Groarke 1999) provides a way to reconstruct
arguments as deductive arguments when NLD requires it, though Johnson
2000 and Godden 2004 argue that NLD is an artificial theory which
forces informal arguments to adhere to an overly restrictive model of
inference. 


### 4.4 Argument Schemes



Argument (or "argumentation") schemes are recurring
patterns of reasoning. Once identified they can be used to evaluate an
argument which is instance of a scheme, or as a template or recipe
arguers can use when they construct an argument which is an instance
of a scheme. Walton, Reed and Macagno 2008 provide a compendium of 96
schemes. Wageman has developed a
  Periodic Table of Arguments
 which provides a systematized account of basic schemes. 



Rules of inference like *modus ponens* and *modus
tollens* can be understood as deductive schemes. Other schemes
commonly used in ordinary arguing include Argument by Sign, Argument
by Analogy, Argument by Example, and Slippery Slope Reasoning. Dove
2016 and Groarke 2019 have shown how visual arguments with non-verbal
visual elements may be instances of common schemes, and have
identified some schemes which are inherently visual. 



The most common approach to argument schemes combines a pattern of
argument with a set of "critical questions" with which it
is associated. The scheme *Argument from Authority*
("Appeal to Authority," "Appeal to Expert
Opinion") and the critical questions it raises can be formalized
as follows. 



> 
> A is an authority in domain D.
>   
> 
> A says that T is true.
>   
> 
> T is within D.
>   
> 
> (Therefore) T is true.
> 



> 
> *Critical questions*:
>   
> 
> 1. How credible is A?
>   
> 
> 2. Is A an authority in domain D?
>   
> 
> 3. What did A assert that implies T?
>   
> 
> 4. Is A someone who can be trusted?
>   
> 
> 5. Is T consistent with what other experts assert?
>   
> 
> 6. Is A's assertion of T based on evidence?
>   
> 
> 



Prakken 2010b understands argument schemes as inference rules, some
critical questions ensuring the truth of an argument's premises,
others ensuring that the context of the inference is appropriate. 



Another approach to schemes builds the answers to critical questions
into a 'full' definition of the scheme, treating them as
required premises in convincing instances of the scheme. Taking this
approach, the scheme *Argument from Authority* can be defined
as follows.



> 
> 
> A is a credible authority in the domain D.
>   
> 
> A asserted X, which implies T.
>   
> 
> A can be trusted and T is within domain D.
>   
> 
> T is consistent with what other experts in domain D assert.
>   
> 
> A's assertion of T is based on evidence.
>   
> 
> (Therefore) T is true. 
> 
> 
> 



The critical question approach to schemes suggests that a credible
argument from authority must include acceptable premises of the form
outlined in the definition of the scheme, and is valid if it is backed
by answers to the scheme's critical questions. Taking the
'full' approach, a valid argument from authority must
include the premises that define it as as a good argument as explicit
(or possibly implicit) premises. In both cases, the result is an
account of premise acceptability and validity which is tailored to
specifically apply to arguments from authority. 



Different argument schemes are a refinement of general **AV**
criteria, creating specific criteria which can be applied to different
kinds of argument. 



When a student essay claims that "we should not stockpile
nuclear weapons" because Einstein told us that this would lead
"to destruction even more terrible than the present destruction
of life" (EXAMPLE 18), this is an appeal to authority which
invokes Einstein as an authority. In order for it to be a convincing
argument from authority, it would need to fully satisfy the conditions
outlined in our definition of the scheme *Argument from
Authority*. 



The attempt to satisfy the requirements this implies produces a
version of the argument which can be summarized as follows.



> 
> 
> EXAMPLE 18 expanded to satisfy the criteria for a convincing argument
> from authority:
>   
> 
> 1. Einstein (A) is a credible authority on nuclear weapons (D).
>   
> 
> 2. Einstein (A) asserted that the stockpiling of nuclear weapons would
> precipitate "destruction even more terrible than the present
> destruction of life" (X), which implies that we should not
> stockpile nuclear weapons (T).
>   
> 
> 3. Einstein (A) can be trusted and questions about stockpiling nuclear
> weapons (T) are questions about nuclear weapons (D).
>   
> 
> 4. The claim that we should not stockpile nuclear weapons (T) is
> consistent with what other experts on nuclear weapons (D) assert.
>   
> 
> 5. Einstein's (A's) assertion that we should not stockpile
> nuclear weapons (T) is based on evidence.
>   
> 
> 6. (Therefore) We should not stockpile nuclear weapons (T). 
> 
> 
> 



This attempt to satisfy the conditions for a good instance of argument
from authority fails because it produces a number of problematic
premises. Other experts disagreed (and continue to disagree) with
Einstein's suggestion that it is a mistake to stockpile nuclear
weapons. More fundamentally, the proposed argument is founded on too
loose an account of nuclear weapons as a domain of expertise. Einstein
is a renowned expert on nuclear physics but this it does not make him
an expert on *the social and political issues* raised by
nuclear weapons. This is something that a convincing version of the
argument would have to establish. 



In some ways, the scheme approach to argument assessment rectifies
problems that arise in systems of informal logic that adopt the
fallacy approach to argument evaluation. For traditional fallacies
which have non-fallacious instances can be understood, not as
fallacies, but as argumentation schemes which are legitimate forms of
reasoning when they are properly employed. Fallacy definitions can be
turned into scheme definitions by identifying a list of critical
questions (or required premises) that specify what is required to make
the arguments in question valid. 



*Ad hominem* is a case in point, for there are many instances
in which criticisms of an arguer (rather than their position) are a
reasonable way to cast doubt on their views. We can specify when this
is so by listing critical questions that determine whether this is so
in a particular case of argument. The basic question that must be
asked is whether there is a good reason why the arguer's views
should not be taken seriously -- a question that subsumes the
more specific questions whether they have repeatedly shown poor
judgment, are biased, lack expertise in the area in question, or are
for some other reason an arguer who should not be listened to. 



Treated in this way, *ad hominem* is a legitimate scheme of
argument, but there are (as there are in the case of all schemes) many
situations in which *ad hominem* arguments are poor instances
of the scheme. In this and many other cases, traditional fallacies can
be regarded as deviations from an inherently correct scheme of
reasoning. 


### 4.5 Testing Systems



Most informal logics combine different ways of evaluating arguments.
In this way, **T** in a particular system tends to be some combined
set of tools that can be used in this endeavor. In most cases,
**T** = {**F**, **AV**, **AS**}, where **F** is some
list of fallacies, **AV** is some kind of **AV** criteria (say,
the standard **ARS** criteria) and **AS** is some set of
argumentation schemes. 



But systems of informal logic can accommodate other, less common
criteria for deciding whether arguments are good or bad, strong or
weak. A system might, for example, incorporate criteria which are
founded on a virtue-based approach to argument (see
 Virtues and Arguments),
 on feminist principles, or on notions derived from rhetoric, theories
of communication, or other cognate fields. 

 The issues raised by
the different kinds of standards that govern arguing in different
kinds of dialogue can be be accommodated by formulating complex
testing systems that include different criteria which apply to
different kinds of dialogue. A system which aggregates these different
criteria may be the best way to build a truly comprehensive account of
real life reasoning.

## 5. Informal Logic Within A Broader Context



Informal logic's attempt to understand argument as it occurs in
a broad range of real life situations continues to evolve in a way
that is influenced by the study of real life reasoning that takes
place within the broader scope of argumentation theory. 



One cognate field of note is Artificial Intelligence (AI). It relies
on step by step accounts of informal reasoning in a wide array of
contexts. Informal logics provide this in a general way that has
influenced the attempt to model argumentation between agents in
multi-agent systems which mimic or assist human reasoning.
Computational models have been applied to large-scale collections
('webs') of inter-connected arguments, and to reasoning
about medical decisions, legal issues, chemical properties and other
complex systems. Automated argument assistance functions as a
computational aid that can assist in the construction of an argument.
Verheij 2014 provides an overview of the issues that this raises. 



The development in the empirical study of real life reasoning is the
study of argument "corpora" -- large collections of
argument drawn from natural language discourse. In an early study of
this sort, Jorgenson, Kock and Rorbech 1991 analyzed a series of 37
one-hour televised debates from Danish public TV. The debates featured
well-known public figures arguing for and against policy proposals. A
representative audience of 100 voters voted before and after the
debate. Their conclusions were compared with standard notions of
"proper" and "valid" argumentation. Other
studies consider corpora made up of large databases of selected
written texts (see, e.g., Goodwin and Cortes 2010, and Mochales and
Ieven 2009). 



Argument mining is a subfield of data mining, or text mining (and
computational linguistics). It uses software and algorithms that
automatically process texts looking for argument structures --
for premises, conclusions, argumentation schemes, and extended webs of
argument. The texts studied include legal documents , on-line debates,
product reviews, academic literature, user comments on proposed
regulations, newspaper articles and court cases, as well as dialogical
domains.
 ARG-tech,
 the Centre for Argument Technology, has played a central role in
studies of this sort. 



Other research relevant to informal logic has highlighted many ways in
which the success of real life arguments depends on aspects of
argumentation which are not well integrated into standard systems of
informal logic. The latter include an arguer's ability to draw
attention to their argument (using "argument flags" that
attract the attention of an intended audience); their personal
credibility, *ethos*, or standing; or their ability to situate
their argument within a broader context of debate or dialogue. The
study of these and other pragmatic, social, dialectical, semiotic and
rhetorical features of arguing will probably play a role in the
continued development of informal logic. 



The expansion of informal logic to account for an ever broader range
of argument is evident in discussions of the use of narratives within
argument. In Plato's *Republic*, Glaucon uses the
mythical story of "The Ring of Gyges" to prove that humans
are inherently selfish. In this and many other situations, stories of
various kinds (accounts of some historical event, biographies, fables,
parables, morality plays, etc) are designed to provide support for
some conclusion. It has often been said that a novel or some other work
of fiction is an argument for socialism, freedom of expression, or
some other value. 



One can understand the argumentative use of narratives in a variety of
ways: as rhetorical embellishment, as a form of argument by analogy,
as implicit generalization (the characters in a story functioning as
variables within such generalizations), or reasoning that requires the
development of unique standards of argument assessment. According to
Fisher 1987, argument itself is best understood as narrative.
According to Nussbaum 1990, literature is a way to better understand,
and argue about, complex moral situations. Within informal logic,
Walton, Reed, and Macagno 2008 identify narrative-based schemes of
argument while others continue to debate the role that narratives play
in ordinary argument (see Govier and Ayer 2013, Olmos 2014, Plumer
2015). 



Informal logic's interest in real life argument has, from the
start, been tied to its interest in the *teaching* of reasoning
skills. In view of this, its interests overlap with fields and
disciplines that study education and pedagogy -- links manifest
in its own influence on critical thinking and the philosophy of
education (and movements like "Philosophy for Children").




Some of the educational issues raised by informal logic are manifest
in the development of critical thinking tests which attempt to measure
argumentation skills. They are used to test the abilities of students
or others and, in a self-reflective way, as an empirical way to test
the success of attempts to teach informal reasoning.



Critical thinking (or, even more so, creative thinking) skills are not
easily assessed using standardized tests which are designed for large
scale use, and typically rely on multiple choice question and answers
(see Sobocan 2021). In real life contexts, what counts as good arguing
(and thinking) is open ended and unpredictable, dialectical, and
influenced by pragmatic and contextual considerations which are
difficult to incorporate within standard tests. The California
Critical Thinking Test reflects the view of critical thinking
elaborated in "The Delphi Report," commissioned by the
American Philosophical Association in 1987, a report that focuses on a
narrow range of critical thinking skills which tends to oversimplify
the competencies required for good informal argument. 



Ennis 2013 provides a comprehensive proposal for dealing with the
issues raised by critical thinking tests, and with other challenges
raised by attempts to teach critical thinking. 


## 6. Informal Logic and Philosophy



The field of informal logic is a recent invention, but one that
continues historical attempts to understand and teach others how to
argue. In the Western philosophical tradition, it begins with the
sophists' fifth century boast that they could teach others how
to be successful arguers. In Aristotle it is manifest in his
systematic account of reasoning, which is expressly designed to teach
others how to argue well. Within the history of philosophy, one finds
numerous other attempts to formulate accounts of argument that can be
used to explain, evaluate, and teach real life reasoning. 



The practice of philosophy itself assumes (and frequently develops) an
account of argument as it assembles evidence for different
philosophical perspectives. Systems of informal logic assume, and
often depend upon, the resulting views of reason, rationality and what
counts as evidence and knowledge. The philosophical issues in play are
tied to complex, unsettled epistemological questions about evidence
and knowledge. 



Mercier and Sperber (2011) argue that reasoning is a practice which
has evolved from, and needs to be understood in terms of, the social
practice of argumentation. Johnson 2000 pushes in the opposite
direction, arguing that a comprehensive account of argument must be
built upon a philosophical account of rationality. Goldman 1999
situates knowledge in the social interactions that take place within
interpersonal exchange and knowledge institutions, emphasizing
informal argument and the constraints which make it a valuable
practice. A 2002 volume of *Philosophica* on Hilary
Putnam's philosophy suggests pragmatism as an epistemology that
best fits informal logic as a discipline. 



Some aspects of informal logic raise deep questions that have
implications for logic and philosophy. One notable feature of informal
logic as it is now practiced is a proliferation of different systems
of informal logic which approach the analysis and evaluation of
informal reasoning in different ways -- employing fallacies,
**AV** criteria, argumentation schemes, methods of formal analysis,
and other models of good argument. One implication is a broadening of
the conditions for argument felicity. 



Other issues are raised by informal logic's recognition that
real life arguments frequently employ visual images, non-verbal
sounds, and other non-verbal elements, challenging the traditional
assumption that arguments are sets of sentences -- or the propositions
("the bearers of truth value") that sentences refer to.
However one understands visual and multimodal arguments, there is no
easy way to reduce them to sets of sentences, for there is no precise
way to translate what we see, hear, experience, etc. into words. 



In its current state of development, informal logic's connection
to philosophy does not lie in its influence on key philosophical
disciplines so much as their influence on it. In North America and
elsewhere, informal logic is a field in which philosophers apply
theories of argument (rationality, knowledge, etc.) to everyday
argument. In keeping with this, philosophers continue to be the core
contributors to informal logic; philosophy departments in colleges and
universities continue to be the core departments that teach the
courses that are its pedagogical focus. 



The influence of informal logic courses on the enormous numbers of
students that enrol in them require that we at least qualify
Rescher's remark (2005, p. 22) that: "The fact is that
philosophy has little or no place in American popular (as opposed to
academic) culture... philosophy nowadays makes virtually no impact on
the wider culture of North America." The extent to which
informal logic's attempt to broadly instill good reasoning
habits within public education and public discussion and debate is
difficult to judge. 



Though informal logic addresses many issues relevant to core
philosophical disciplines (most notably, epistemology and philosophy
of mind; evident in the work of Goldman, Crosswhite, Thagard, and
others), it has had limited impact on mainstream approaches to their
subject matter. Woods 2000 has speculated on the reasons why. In part,
informal logic's position within philosophy reflects the broader
fragmentation of philosophy within North America, Rescher 2005 (p. 4)
writing that: "The most striking aspect of contemporary American
philosophy is its fragmentation. The scale and complexity of the
enterprise is such that if one seeks in contemporary American
philosophy for a consensus on the problem agenda, let alone for
agreement on the substantive issues, then one is predestined to look
in vain." 



In this context, it can best be said that informal logic, like applied
ethics, has become a standard offering that helps sustain philosophy
departments in North America by contributing to what Rescher describes
as "The rapid growth of 'applied philosophy'
...[that] is a striking structural feature of contemporary North
American philosophy." (p. 9). The goal of applied philosophy is
philosophically informed and nuanced reasoning that addresses complex
real life situations. Informal logic is one field which has made a
valuable contribution to this goal.