ISSA Proceedings 1998 – Informal Logic: The Two Schools
The two schools are those of the fallacy critics and the argument analysts. The distinction I draw is in terms of areas of interest and emphasis within informal logic as exhibited in the writing of several informal logicians, and I will deal very much with general trends and tendencies. The distinction can prove useful, I maintain, even if a fallacy critic responds “I do some of the same things you ascribe to argument analysts.” The heart of the matter is where the writer places his or her highest priority, and how this affects the topics chosen and the methods of work.
Accordingly I will first distinguish the two schools by their different emphases and some typical writers, note what the two have in common, and touch on the development of informal logic as a discipline. There follows a treatment of two differing conceptions of argument. After this, some distinctions within each school are explored. Finally I summarize and conclude this survey and analysis.
2. The Schools Distinguished
Fallacy critics seize on informal logical fallacies as the main object of their study, such as begging the question or the ad hominem. They focus on argumentation in natural language where such fallacies occur, approaching it from the standpoint of a critic. They regard argumentation as a process, much as a drama critic observes the tragedy unfolding before her on the stage. Our drama critic (let us assume she is good at her job) will be sensitive both to the strong points of the production as well as to its weaknesses. But the fallacy critic is by orientation more sensitive to weaknesses or lapses in argumentation, since that is of course what logical fallacies are (whatever else they may be). On the practical side, the fallacy critic scrutinizes a text for fallacies and points them out, or finding none, allows that the text passes muster. On the theoretical side, the fallacy critic is interested primarily in a theory of criticism, which concerns what makes fallacious reasoning fallacious, and secondarily in a theory of argument, an explanation of the kinds of discourse and circumstances in which fallacies occur. The leading writers of this school are Douglas N. Walton, John Woods, Ralph H. Johnson, and J. Anthony Blair.
Argument analysts take argument in natural language as the main object of study. They tend to define argument broadly as any case of a claim or statement backed up with reasons. Argument analysts are inclined to regard argument as a finished product which they then slice up into its constitutent parts for study. Not being guided by traditional or recent notions of fallacies, analysts are more concerned with describing and categorizing discourse. They put more stress on distinguishing argument from related uses of language like problem solving and explanation. The analyst relates to argument much as a scientist to a specimen. The scientist analyzes the specimen then sums up the result of her analysis. Perhaps the main difference between scientist and analyst is that the scientist as such does not evaluate her specimen relative to human purposes, instead aspiring to remaining value free. The work of an argument analyst on a specimen, however, culminates in the judgment that the argument is weak or strong on the basis of how little or much support the premises provide for the conclusion.
On the practical side, the analyst identifies an argument, analyzes it, and then evaluates it. Not being focussed on fallacies, she may be more sensitive to the outcome being that the argument is strong or good. But typically no traditional or current literature provides her with a body of good-making features that would complement the bad-making ones of the fallacy critics. On the theoretical side, analysts investigate matters arising from their central activity like identifying and formulating missing premises of an argument, or distinguishing ways in which premises relate to an argument’s conclusion like convergent and linked. Leading writers of this school include Stephen F. Toulmin, Michael Scriven, Trudy Govier, David Hitchcock, Alec Fisher and James B. Freeman.
3. What the Two Schools Have in Common
The two schools share a strong interest in argument in natural language and the conviction that it is important to be able to deal with it effectively. They are agreed that traditional (e.g. syllogistic) and recent (e.g. symbolic) formal logics inadequately address this need, and that this inadequacy stems from the formalism of formal logics.
For a variety of reasons the need for techniques of analyzing and evaluating argument in natural language is deemed sufficiently pressing that a new (and hence informal) logic must be devised to address it. One frequently cited reason is that we must be able to analyze and evaluate natural-language discourse on matters of public policy in order to contribute and function effectively as citizens in a democracy.
Many informal logicians are linked by similar educational and disciplinary backgrounds, and by a strong interest in the teaching of logic. Most members of both schools are academically trained philosophers with more or less background in those formal logics brought to fruition in the 20th century, propositional and predicate calculi. Most have taught introductory level college courses in logic. Most came to reject the claim that such formal logics were the best vehicle for teaching the practical reasoning skills so sorely needed by many of today’s students. Most have a strong interest in creating teaching materials that reflect developments in informal logic for better addressing such needs. For example, all of the writers mentioned above (both schools) have authored or co-authored one or more college textbooks on informal logic, reasoning, or critical thinking designed for an introductory level course (Woods and Walton 1982; Johnson and Blair 1994; Toulmin 1984; Thomas 1986; Scriven 1976; Govier 1992; Hitchcock 1983; Fisher 1988; Freeman 1988).
4. Informal Logic as a Discipline
Although there is no dearth of theoretical work by argument analysts, the development of informal logic as a field – as a discipline – has been driven more by the fallacy critics. They may rightly be called fallacy theorists in this connection. Fallacy critics tend to think of themselves as logicians cultivating a sub-discipline of logic with an ancient history, a tradition (of questionable distinction), and comparative recent neglect. C.L. Hamblin (1970: 12) notoriously characterizes the typical modern textbook treatment of fallacies thus:
[It is] as debased, worn-out and dogmatic a treatment as could be imagined -incredibly tradition-bound, yet lacking in logic and in historical sense alike, and almost without connection to anything else in modern Logic at all. This is the part of his book in which the writer throws away logic and keeps his reader’s attention, if at all, only by retailing the traditional puns, anecdotes, and witless examples of his forbears.
Leading fallacy critics by and large subscribe to Hamblin’s assessment (but for a recent volte face on this see Johnson 1995: 153-166) and set themselves the goal of remedying (in different ways) weaknesses in this corner of logic.
Argument analysts are somewhat less inclined to view themselves as logicians, even though they accept being classed as informal logicians. Some seem sceptical that much of value is to be learned from the tradition of informal fallacies (Hitchcock 1995). The tendency is to either nod politely in the direction of informal fallacies or to simply ignore them. Accordingly argument analysts are much less inclined to view themselves as jostling with formal logicians for space and sunshine in the territory of logic. They are thus less engaged polemically with formal logic, and tend to be diffident toward viewing and explicitly defining themselves as logicians.
The development of informal logic as a discipline, aware of itself as a discipline, owes much to the writings of Woods & Walton of the 1970s and early 1980s (collected in Woods & Walton 1987), and to a number of articles and books by Walton since that time (e.g. Walton 1987; Walton 1992; Walton 1992a). But it owes as much and perhaps more to the prodigious activities and fierce energy of Johnson & Blair. A series of articles co-authored by them beginning in 1980 (Johnson 1995: 2-51; Johnson & Blair 1985) has stressed defining and developing informal logic as a discipline.
They organized three international symposia on informal logic, in 1978, 1983, and 1988, all at the University of Windsor in Ontario. They started up the Informal Logic Newsletter in 1978, which became the journal Informal Logic in 1985, and have ably edited this principal medium of communication for specialists in the field. All four fallacy critics are found frequently at meetings of learned societies, or (in Johnson’s case particularly) at conferences on critical thinking, informal logic, or argumentation, promoting the field by reading papers, conducting workshops, and serving on panel discussions. While there are many other able writers in the field of informal logic, these four may be more definitive of it as a field.
5. The Concept of Argument
Until recently much of the writing on the concept of argument came from fallacy theorists. As logicians they realized that formal logicians also work with a concept of argument. They wanted their endeavor to be distinct from that of formal logicians, so they sought to define argument in a distinct fashion. As is often the case, the impulse to push off in a new direction comes from dissatisfaction with current practice.
Argument analysts tend to agree with formal logicians that argument is adequately defined as cases of claims being backed up with reasons (cf. Hitchcock 1983: 31; Freeman 1988: 20). When we use arguments, we try to persuade in a rational way by citing evidence or reasons to back up our view. The evidence or reasons are called the premises, and the view being defended is called the conclusion (Govier 1985: 1) arguments are “discourses containing statements that are set forth as supporting, proving, or making probable what is said in other statements” (Thomas 1986: 10).
The main interest of analysts is in techniques of analysis and evaluation, and they tend to accept as argument those creatures their techniques applied to. Thomas (1986), for example, titles his textbook Practical Reasoning in Natural Language. He expects his readers to realize that natural language is distinct from the artificial languages of symbolic logicians (e.g. Russell-Whitehead notation, Polish notation), and also to realize that practical reasoning differs from theoretical reasoning (e.g. in mathematics or physics) by being of potential use in everyday life. For anyone who is unclear what “practical” means in this sense, Thomas includes recipes and claims from advertisements among his examples and exercises. This analyst definition of argument is a minimalist definition in its sparse defining features, but a veritable Jacksonian democracy in its broadly inclusive extension.
One might object that it is unfair to analysts to look to their textbooks for a fuller picture of the concept of argument, but at least in the 1970s and 1980s argument analysts devoted little attention to defining argument, even in their theoretical work. Thus e.g. Govier (1987: ch 2) devotes a chapter to the question whether a theory of argument is possible, but very little of it deals with what an argument is. I point this out not to claim that Govier should have dealt with this topic, but as evidence that for argument analysts “argument” was a relatively unproblematic concept.
What did render the concept problematic was initially fallacy critics, Johnson & Blair foremost, disputing the claim of formal logicians to have techniques adequate for the analysis and appraisal of arguments in natural language. These writers find argument defined by formal logicians in much the same way as it is by argument analysts among informal logicians. So in attacking the former target the latter comes into their crosshairs also.
On the positive side fallacy critics prefer to define argument by focussing on the socially interactive process which produces it. Many fallacies commonly classified as fallacies of relevance can be understood as violating rules of reasonable procedure in a dialogue. One can always criticize an ad hominem in the spirit of the above minimalist definition by indicating that the premises are irrelevant to the conclusion, making the argument weak. But exploring the dialogue in which it occurs, the roles of the participants, which moves are open to them and which closed, and which moves they ought to make, gives us a richer and fuller awareness of why an ad hominem is a fallacy. An issue of substance is being debated and serious reasons or evidence occupies the field, to all of which personal circumstances and characteristics of the participants are at most of peripheral significance. The participants have a duty to stick to the point, which one of them violates by dragging some personal trivia about the other into the debate. Thus the ad hominem fallacy, and Walton (1992b: 32) defines argument accordingly:
Argument is a dynamic social interaction, in which participants engage in a dialogue exchange … a social and verbal means that two parties can undertake together in order to resolve a conflict or difference between them.
Blair and Johnson (Johnson 1995: 92) prefer to stress the dialectical aspect of argument:
To say that argument is dialectical … is to identify it as a human practice, an exchange between two or more individuals in which the process of interaction shapes the product.
From the vantage point of this definition, Blair and Johnson (Johnson 1995: 90-94) criticize the minimalist definition on two counts:
1. It is structural rather than dialectical.
2. It views argument as product rather than process.
Argument as essentially dialectical is said to avoid such shortcomings.
These four features are stressed:
1. As product, an argument must be understood against the background of the process that produced it, i.e. background beliefs shared, or debated by the community.
2. The process of argumentation presupposes at least two roles – one a questioner of a proposition, the other the answerer of these questions.
3. The process of argumentation is initiated by a question or doubt of a proposition.
4. Argumentation is purposive – the questioner challenges the proposition, the answerer defends it.
Argument analysts too have conceived argument as dialectical, though they have come only more recently to employ this term, and though the idea has remained in the background of their work. The contrast Toulmin (1958: 6f.) draws between the mathematical logic he rejects and a logic concerned with the practical assessment of arguments on the jurisprudential model he which he advocates, closely parallels the Blair-Johnson contrast of a rejected formal deductive logic and argumentation as pragmatic (given of course the Anglo-American adversarial judicial process). More recently Freeman (1991: 17-26) explores dialectical aspects from the vantage point of an argument analyst.
6. Distinctions Within the Schools: Fallacy Critics
Among fallacy critics there are a marked differences on the role allotted formal logics in the criticism of fallacies. Many (if not most) informal logicians expect little illumination of informal fallacies from formal logics, especially from the varieties of first-order predicate logic that have become the 20th-century formal logician’s stock in trade. The group of influential and carefully argued papers by Woods and Walton in the 1970s and early 1980s (Woods & Walton 1989) are however the closest that leading informal logicians get to formal logic. Formal analysis here is both necessary and the best way of critiquing fallacies. But the logical systems drawn on are not linear descendents of the Russell-Whitehead first-order predicate calculus. For example, Kripke’s intuitionistic logic is called in service for the petitio principii, as is dialectical game theory for this fallacy and our above one of complex question, and a plausibility logic is drawn on for the appeal to authority.
Scriven, Van Eemeren, and Grootendorst expressed doubts (in discussion at the International Conference on Argumentation in Amsterdam, June 1986) whether the gain from such formal analyses is sufficient to justify wheeling this much heavy formal logical artillery into the field against informal fallacies. Groarke (1991) distinguishes successfully portraying the forms of informal fallacies from illuminating specific fallacies. He seems on target in granting the latter achievement yet denying the former. It isn’t at all clear to me that informal fallacies even have formal structures. Certainly they do not in the common sense that they are best described as instantiating invalid forms of argument, where “best” means “most useful for detecting and critiquing” the fallacy. And any fallacy best described as instantiating an invalid argument form would be a formal fallacy, not an informal one. Yet Woods and Walton frequently succeed in providing fresh perspectives and valuable insights into the informal fallacies they examine.
In subsequent writing Woods (1987) insists on “The Necessity of Formalism in Informal Logic,” and draws on a mathematical model to illuminate the question of a unified theory of fallacies (Woods 1994). Walton’s work on the other hand has developed more in the direction of the Amsterdam School (Eemeren 1987a; Eemeren & Grootendorst 1995) to view fallacies as violations of procedural rules of reasonable dialogue like “the failure to state or address an issue, failure to document a source of expertise, failure to ask reasonable questions, failure to stick to the point, use of emotions to avoid argument [or] prejudicial use of unclear terms that may be vague or ambiguous” (Walton 1987: 328). He may have arrived at this point relatively independent of the work of van Eemeren and others, since he had already published a book on logical dialogue games (Walton 1984) before the work of the Amsterdam School was much known in North America.
Blair and Johnson (Johnson 1995: 87-90) are at the opposite pole from the early Woods and Walton on the use of formal logic for criticizing fallacies. Interestingly recent fuller bibliographies of work in informal logic (Hansen 1990 and Schmidt & Hansen to early 1998 in Hamblin 1970; 1998 reprint) list no articles by Johnson and Blair jointly or separately critiquing an individual fallacy.
In their estimate, formal deductive logic claims to provide the materials for adequate criticism of fallacies, but falls far short of delivering on that claim. These writers explicitly reject the claim that we are looking for true premises in an argument of valid form to constitute a sound argument. In fact, they would expunge the very terms “true,” “valid,” and “sound” from the informal logician’s vocabulary (Johnson however appears to re-introduce “true” in “The Problem of Truth for Theories of Argument, read at this conference). Blair and Johnson oppose argumentation in the dialectical sense to formal deductive logicians’ preoccupation with implication or inference. They also discourage the use of “implication” or “inference” in informal logic. Inference or implication is not necessarily dialectical in that it does not depend on exchanges between two persons. It is not necessarily controversial, and it can progress linearly; argument on the other hand is essentially controversial, so it can progress only against the background of diverse viewpoints.
The Blair-Johnson view of argument as necessarily dialectical may have developed in interaction with the Amsterdam School. Lately Walton (1989: 114f.) has taken the position that argument can be conceived as a semantic core “normally surrounded by pragmatic structures.” The semantic core comprises premises and conclusion, the pragmatic structures some at least of what Blair and Johnson term dialectical. Johnson (in a paper read at Conference 95 on Critical Thinking, George Mason University, June 1995) seems very close to Walton’s position with his distinction of semantic core and dialectical tier. If after traversing this distance you are wondering whether there is a sense in which fallacy critics are still fallacy critics, you might recall the traditional distinction of fallacies of equivocation from fallacies of relevance. Fallacies of equivocation tend to occur in the semantic core, those of relevance in the pragmatic structures/dialectical tier.
7. Distinctions within the Schools: Argument Analysts
There is a persistent trend among argument analysts to separate the tasks of identifying, analyzing, and evaluating arguments (even though in practice there seems always to be some overlap). To identify an argument is to pick it out from surrounding discourse that is not argument, and to do this by noting certain features distinctive to argument. The minimalist definition supplies the distinguishing features. They are as charged by some fallacy critics structural and they are based on argument as product. Yet they serve the purpose well enough to be widely used. To analyze an argument is to clarify how the premises are advanced in support of the conclusion, and occasionally to supply unstated premises. To evaluate an argument is to decide on the basis of the analysis, and relevant information external to the argument, whether the argument is weak or strong. The trend to distinguish these three tasks is strongest in the work of Thomas (1986) and those influenced by him, although it may be traceable back to Beardsley (1975) and is clearly present in others (e.g. Scriven 1976: 39 et passim).
Note that analysts define argument as reasons advanced in support of a claim, not as reasons supporting a claim. This is done not to avoid intentionality in the definition (where the intent to prove would count as proof itself), but to keep the identification of an argument separate from its evaluation. Reasons support claims only in successful or strong arguments; they are advanced in support of claims but do not actually support those claims in weak arguments. Weak arguments, however, remain arguments and are not by the circumstance of their weakness transformed into some non-argumentative form of discourse. That informal logic should deal with weak as well as strong arguments seems obvious, but that how one defines “argument” affects this objective is less so.
Another way of putting this is to say that analysts aspire to evaluatively neutral criteria for the purpose of identifying discourse as argument. For them “argument” is a descriptive term that classifies a piece of discourse as distinct from poetry or grocery list. There are still important differences among analysts, who by and large agree on this definition, over what is to count as argument. Thomas, for example (1986), takes explanations in general into the scope of argument. Scriven (1976: 65f.) does not count explanations by cause and effect as arguments, and other analysts (Govier 1987: 159-176; Hoaglund 1987) have countered with cases of explanation that are not argument and argument that are not explanation. It does appear that an explanation can clarify or reduce puzzlement without attempting to prove anything, i.e. without being an argument. But it also appears that some explanations, such as those used to justify actions as morally right or counsel against them as morally wrong, do claim probative force and hence might appropriately be treated as arguments.
Govier (1987: 65-74), following up a proposal by the moral philosopher Wellman (1971), refers to explanations that justify as conductive arguments. The jury is still out on whether “conductive” picks out a distinct species of argument, but informal logicians in general are restive with the traditional distinction of arguments into deductive and inductive. Analysts in particular have been pressed to look at what is netted by the criteria of the minimalist definition with fresh eyes, since some choose not to be guided by even improved accounts of informal fallacies. What fresh eyes have seen has been reported (in the absence of any accepted descriptive terms) by hand as arrow diagrams to depict claims of logical support. The arrow points from premise to conclusion and represents the claim that the premise provides at least some logical support for the conclusion. Thomas (1986), Freeman (1988), and Fisher (1988) are among those analysts who make extensive use of diagraming, with Thomas and Fisher focusing especially on conditional or suppositional arguments. Analysts concentrating on types of argument where diagrams have yet to offer much aid use them correspondingly less. Govier (1992) with some emphasis on arguments by analogy loosely fits this description.
Diagramers fall into three groups, depending on the direction their arrows point: uppers, downers, and lateralers. The Amsterdam School of speech communication theorists are uppers (Eemeren & Grootendorst 1984: 93) as well as the analyst Finocchiaro (1980: 367, 378, 388f. et passim). But uppers have been the least influential of the three in North America. Toulmin (1984) and his followers are lateralers. They fit all arguments into one scheme beginning with grounds on the left, with warrants, backing, modality, and rebuttals all contributing en route to the claim on the right. In practice Toulmin’s lateral diagram functions somewhat like a flow chart of items to check off in analyzing and evaluating an argument. It does not distinguish argument types, and users of it encounter difficulty making the distinctions of grounds, warrant, and backup it calls for (Johnson 1995: 122-135; Freeman 1991: 49-88).
The downer technique which has now become “the standard approach” (Freeman 1991: 1) owes more to Stephen N. Thomas (1986) than any other single writer. Thomas states that he adapted this technique from the earlier work of Monroe Beardsley (1975), but the scope and facility of application contributed by Thomas have greatly extended its use among analysts. Thomas distinguishes four basic argument patterns: linked, convergent, divergent, and serial. The linked and convergent are arguments with a single conclusion whose premises work together in different ways. The other two patterns have multiple conclusions, the serial, one or more intermediate conclusions, and the divergent, two or more final conclusions.
Few topics have exercised analysts more than the distinction of linked from convergent arguments (e.g. Vorobej 1994; Conway 1991; Yanal 1984). Indeed fallacy critics (Walton 1996) and speech communication theorists (Snoeck-Henkemans 1992) have joined the debate. Roughly speaking, the premises of a linked argument must work together or cooperate to provide a measure of support for the conclusion. In the convergent argument each premise provides a measure of separate, independent support. Most arguments in formal logics, mapped onto informal patterns, are linked. Every valid syllogism, for example, has at least one universal premise and so at least one term distributed in its premises. Without this universal premise, the other premise usually contributes little support to the conclusion. Toulmin’s argument scheme also greatly favors linked arguments, since every argument will have grounds (facts of the case) and a warrant (general law) licensing the inference to the conclusion.
Analysts like fallacy critics have grappled with the problem of developing a terminology accurately descriptive of argument yet free of misleading associations carried over from formal logics. Toulmin (1958) uses “grounds” in place of “premise” to better distinguish his endeavor from that of formal logicians. Thomas prefers “reason” to “premise”, indicating that “the use of the term ‘premise’ is often taken to indicate that the reasoning in question is supposed to be deductively valid” (1986: 133). Deductive validity is a particularly inappropriate criterion of argument strength for informal logic, since judged by it nearly all natural-language arguments fail.
Another way of discussing argument strength in formal logic is to indicate that it is impossible for a formally valid argument with a false premise to prove its conclusion. This implies that every premise of an argument in formal logic is necessary, or that once correctly identified as a premise that statement is essential to the proof of the conclusion. The special problem for the analysts in informal logic arises in terming the support statements of a convergent argument “premises”. Since the convergent argument is one in which by definition each premise contributes a measure of separate, independent support, it is always possible that a given convergent argument may have one weak or even false premise yet still be strong (due to support contributed by other independent premises). However a premise cannot at the same time be a statement both essential and unneeded to establish a conclusion (Hoaglund 1988).
Facione (1989) would eliminate the strong argument with a false premise by blocking the use of “premise” in informal logic. But an important task of analysts is to uncover unstated or tacit premises (e.g vid. Grennan 1994; Govier 1989), and “unstated reasons” or “tacit grounds” does not seem to pick this out as effectively. Schmidt (1990) would interpret the convergent argument to comprise two or more separate arguments, a position also advocated by Gratton (1989: 3): “Since an arrow in the diagram of a convergent argument is supposed to represent an inferential link, or a link of support, … and since every link of support constitutes an argument, then the presence of two arrows implies that there are two arguments.” In the upper diagrams of the Amsterdam School (Snoeck-Henkemans 1992), the convergent argument contrasts with the linked as multiple compound to coordinately compound, and here too the convergent is interpreted as comprising separate arguments (Freeman in “Argument Structure and Disciplinary Perspective” read at this conference points out how this prevents multiple compound from coinciding with convergent arguments).
But this solution is very costly for informal logic. Without the convergent argument it is much harder if not impossible to do justice to most extended arguments. Pioneers of informal logic cite the need to deal effectively with extended arguments as a prime objective of informal logic (Johnson 1995: 19-22). Also, rejecting the convergent argument as a separate unit as suggested by Schmidt and Gratton imports into informal logic the same tunnel vision that has prevented formal logics from ever developing effective techniques for dealing with natural-language arguments. As Freeman argument depends on that specific argument: “Being essential to the cogency of an argument is an accidental property of some premises on some occasions. It is not part of the ‘essence’ of a premise” (cf. Hoaglund 1990).
To sum up, the starting point of fallacy critics is the logical tradition of informal fallacies. Early critics attempted to illuminate them by drawing on formal logics, but the recent trend is to situate the fallacies in their larger social context of debate and discussion. Analysts have worked with a minimalist definition of argument, and have struggled to understand different ways in which premises and conclusions can relate in the variety of arguments encountered in natural language. Critics differ over whether and to what extent formal logics are helpful for the problems of informal logic. Analysts differ over whether explanation counts as argument, and over what types of argument there are with the linked-convergent distinction
attracting much attention.
Limitations of time have prevented me from more than hinting at the fruitful interaction of informal logicians with the work of the Amsterdam School of speech communication. Nor have I even been able to hint at the connections (particularly of analysts) with those working in critical thinking in North America, where argument analysis is considered by some to be a model critical thinking activity. The briefest of references above to Peter Facione must suffice – Facione is the designer of the California Critical Thinking Test and is currently conducting research into critical thinking dispositions.
My purpose in drawing the distinction of fallacy critics from argument analysts is to aid those looking in on informal logic to better orient themselves toward work in the field, and to provoke informal logicians themselves to consider how what they are doing relates to work by others in the field.