Chapter Six: Analyzing Arguments



I.    Introduction

This is the first of two chapters devoted to the analysis of arguments.  The theoretical discussion in Chapter 6 includes discussion of formal analysis, content analysis, and context analysis.  Formal analysis comprises examination of the forms of argument that are structurally strong, in the sense that their propositional structures tend to ensure that the truth of the premises increases the likelihood that the conclusion is also true.  Structurally strong arguments come in two broad types, viz., deductively valid arguments and inductively strong arguments.  In addition to describing these, I have taken time to present a fair bit of detail about specific instances of argument types that fall under these two categories.  This, however, is only a brief and rather unsystematic introduction to the logic of these argument types; if you are interested in working on these in greater depth, I recommend consulting one of the books in the bibliography at the end of this Applications section.  Content analysis is not something that we can do much of, since it is really not in the province of critical thinking studies but rather in the province of specific disciplines.  Context analysis concerns evaluation of the context of the arguments, where this includes the discourse context as well as the relationship between the specific arguments and the plans of the arguers.  In addition to a bibliography, I include in this section discussion of teaching points and instructional ideas, and I analyze the arguments that have been identified in Chapter Four and reconstructed in Chapter Five.

II.    Teaching Points

  1. Don't move too quickly into evaluation.  When you begin with arguments, you will get evaluation right away.  We are inclined to engage with arguments critically, either in attack mode or in defense mode.  In the early stages of critical thinking instruction, it is good to allow students opportunities to evaluate and critique.  This reinforces the value of critical thinking in their own lives, as the activity will be familiar and relevant.  However, once you hook the students with the idea of critical thinking as argument analysis, you should back off from evaluation and concentrate on identification and reconstruction.  In addition, you should emphasize the value of charity in argument analysis---this is often lost on students new to critical thinking skills instruction.  Be sure that they are proficient at spotting and detailing arguments before you work on the multifaceted task of deep argument analysis.

  2. Evaluation requires attention to form, content, and context.  As I argued in the theory section of this chapter, evaluation can be conducted along three dimensions, viz., form, subject matter, and context. Students will be inclined to evaluate along the subject matter dimension, but not along the form and context dimension.  Form in particular will be foreign to them, unless they have had some exposure to logic.  Be sure to call attention to this as you teach argument evaluation.  This could be done explicitly and systematically, or it could be done on the fly.  For instance, you might concentrate in discussion on labeling evaluations according to whether they focus on form, content, or subject matter.  Alternatively, you might structure any evaluative discussion so as to elicit comments according to whether they concern form, content, or context.  In any case, if your students are able to distinguish these three dimensions, their evaluations will be deeper and more sensitive to the nuances of the argument in question.

  3. Don't ignore logic.  It is easy to ignore logic, if you are unfamiliar with it.  I strongly discourage you from doing this.  If you plan to teach critical thinking skills in an explicit way, you should spend some time familiarizing yourself with the nature of logic and some of its details. The theory section of this chapter is intended to provide this kind of introduction.  Failure to give logic its due will vitiate the formal dimension of argument analysis.   You needn't become a logician to do this, or even all that proficient in logic, but you should be willing to call attention to the logic of the arguments you evaluate and ask whether it is in good shape or bad.  Familiarity with the differences between deductive and non-deductive logic, along with some specific patterns in each, should do the trick.  

  4. Stress patterns of reasoning.  Logic is the study of truth-conducting patterns of propositions.  As such, the formal dimension of argument evaluation will focus on the abstract and repeatable structure of the argument in question.  If students are sensitive to the fact that familiarity with a few structural patterns can give them the ability to evaluate an infinite number of specific arguments (although nowhere near all of them, mind you), this should impress upon them the significance of patterns to critical thinking.  While patterns of reasoning are obviously crucial to formal analysis, they are equally although perhaps less obviously crucial to subject matter and context analysis.  With respect to all types of evaluation, the goal is to determine whether the relevant standards are met, and the ways in which specific arguments meet or fail to meet these standards are generally repeatable.  Familiarity with these patterns of content and context can simplify the project of evaluation.  (But be careful---sensitivity to patterns can easily bleed over into stereotyping.  Remain cognizant of the individual characteristics of the arguments you evaluate.)

  5. Work up your own list of subject matter standards.  I have focused most of my attention on formal analysis in the theoretical part of this chapter, primarily because formal characteristics are general and do not vary from discipline to discipline.  Given this, a philosopher can say something substantive about them.  Formal analysis is important, but so is subject matter analysis.  In fact, since subject matter analysis requires knowledge of the subject, this will likely be the level of analysis you will wish to emphasize in your class.  However, to do this systematically, your students will need to know the standards that are appropriate.  Most of what you do in the class will likely be related in important ways to the teaching of these standards, but it can be very helpful if you codify the regularities and norms that are relevant to analysis of arguments in your discipline and convey these to your students.  In many cases, this may require only moving through a textbook and noting general criteria; in other cases, it may require case-by-case extraction of the relevant standards.

  6. Emphasize detailed critiques. Be sure that whenever you evaluate arguments, your evaluations and those of your students are detailed.  Rejection or affirmation of an argument is a start, but only a start.  Be sure to model and expect evaluations that are specific and labeled, i.e., that focus on the details of the argument and are annotated to indicate whether they are formal, subject matter, or context analysis.  In many cases, detailed critiques are themselves arguments.  These can be supportive or critical, with conclusions that affirm or deny the conclusion of the target argument.  Emphasis on detailed critiques will help train students to  be active participants in persuasive dialogue, exchanging argument for argument.

III.    Instructional Ideas

  1. Handouts, handouts, handouts.  Prepare and distribute a 1-page handout on argument logic.  This can be taken from the theory part of this chapter or from your favorite logic book.  Do this early in the evaluative stage of critical thinking instruction.  In addition, handouts that describe the framework of evaluation, with its three dimensions, and the subject-specific standards, with illustrations, can be very useful as aids to instruction.  If you do construct and distribute these, be sure to refer to them with regularity.

  2. Structure your evaluative exercises.  If you ask the students to work individually or in groups on argument evaluation, ask explicitly for formal, subject matter, and context evaluation, explaining what these are in advance.  You might look for arguments that are relevant to your course and bring them in to subject them to evaluation along these three dimensions.  It can be helpful to select them so that each of the three dimensions is weak in at least one of the examples. 

  3. Demand details in discussion.  If you are evaluating arguments in class discussion, be sure to require students to flesh out their evaluations.  Respond by asking them to describe the type of evaluation they are offering and to put their evaluation in the form of an argument. 

IV.    Illustrations

This section includes close analysis of the arguments identified in the Applications section of Chapter Four and reconstructed in the Applications section of Chapter Five. In the main, I have not issued final judgments, but rather have spelled out considerations that should bear on the final judgments that you form vis-a-vis these arguments.

II.1 An Interview with Mario Benedetti

Formal Analysis:

We have reconstructed eight arguments found in the Benedetti interview. Of these, (E) and (H) are non-deductive arguments, with (E) being inductive and (H) being abductive. The rest are deductive arguments. We will consider the arguments in turn.

(A): This is a deductively valid argument, so long as we interpret the positive changes mentioned in (3) as changes in the basic needs of humanity mentioned in (P1), and so long as we allow that expansion in the conclusion is a gloss on the point that follows from (3) and (P4). (In general, if a conclusion of a deductive argument contains information that is not found in the premises, explicit or implicit, then the argument will be invalid—remember that deductively valid arguments contain conclusions that do not go beyond their premises.) If we interpret (3) and the conclusion in these ways, (3) follows from (P1) and (P2) by modus tollens and (C) follows from (3) and (P4) by modus ponens. We have given Benedetti (P2)—without it, the argument is invalid—because his remarks in the interview context would seem to imply it.

(B): This argument has the form of a modus ponens, but since it is a complicated mixture of propositional and categorical elements, it is better interpreted in a different way. The surface form of (P1) is that of a conditional, but in fact it is a universal proposition that expresses a rule: all guerilla groups that wish to take authoritarian power are implausible. The second step asserts, in effect, a universal claim about the category of guerilla groups that are not EZLN, and together with (P1), these imply (C) through categorical inclusion. The category of groups mentioned in (P2) is contained in the category mentioned in (P1) and so inherits all of its faults, one of which is implausibility. Note that this argument, as written, does not assert that EZLN is plausible. If you interpret Benedetti’s remarks as asserting the plausibility of EZLN, you will certainly have difficulty accepting this argument as a comprehensive account of his attitude toward the group as expressed in this interview.

(C): This is a valid modus ponens argument, although to get the antecedent of the conditional expressed by (P3), one must conjoin (P1) and (P2), that is, one must combine them into an ‘and’ statement. As with (P2) in (B), the conditional (P3) is implicit—I credit Benedetti with it as it is needed to connect the explicit claims (P1) and (P2) to the conclusion, and there is nothing that Benedetti says that would suggest an unwillingness to embrace it; as such, the Principle of Charity enjoins me to credit him with it. It is worth noting that, as written, (P3) differs from (P1) in argument (B) in that it does not express a general rule; rather, it asserts a connection between very specific facts about Mexico. However, it is reasonable to think that the plausibility of (P3) as a claim depends on the plausibility of the general rule of which it is an instance, viz., "If a guerilla group gains respect in a country while the government of that country loses respect, then change will occur in that country."

(D): This is a valid modus ponens argument. Once again, the conditional is implicit and is necessary to get from (P1) to the conclusion. The logical nature of this conditional would appear to make it inconsistent with the Principle of Charity, given that the antecedent describing a condition that would appear to undermine the possibility of the consequent (on the assumption that you get ready for changes only in advance of the changes) and crediting an arguer with an inconsistent premise is hardly charitable. Nevertheless, it is necessary to get from (P1) to (C)—without it, the argument would be invalid. I am inclined to credit Benedetti with the claim and then interpret it in a way that avoids the inconsistency.

(E): This is an inductive argument, and as such is compelling only if it is inductively strong. Surveys, polls, and questionnaires are instruments for acquiring a large number of individual opinions about an issue from members of a group so that one can generalize over the entire group. As such, they are designed to produce inductive arguments for universal conclusions. They are compelling only when there is good reason to believe that the opinions gather truly represent a cross-section of the group in question. One must believe that those who gathered the opinions did so in a way that was unbiased and representative. In this case, we know nothing about the nature of the people who conducted the surveys or about the surveys, and this certainly vitiates the argument in its present form. Of course, if one has reason to believe Benedetti—perhaps he is well-known for his veracity—then that might shore up the report, but by itself, it yields an inductively weak inductive argument.

(F): This is a deductively valid argument of the propositional form. The third step follows from the first two according to the rule modus tollens, and then it combines with the fourth step to generate the conclusion by modus ponens. Structurally, this argument is identical to (A) above. There is, however, an interesting difference between the two—this argument is practical in nature, given that it concerns Benedetti’s own actions, whereas (A) is theoretical, related as it is only to what we should believe about humanity. As we note below in content analysis, this difference stands this argument in much better stead than (A).

(G): This is a deductive argument that is quite complex in nature. The first step expresses a categorical proposition, viz., that all corrupt governments generate poverty among their people. The second and third steps are intended to establish that Mexico has both corruption and poverty, and with this, (4) is asserted as an instantiation of (P1) in the case of Mexico. This is a categorical argument, and as written, it is not valid—other things could generate poverty, and while Mexico has a corrupt government, it is not clear that the poverty from which it suffers must have been caused by that corruption; rather, it could have been brought about through the actions of other causes. However, it should be noted that this is not the only way that we can look at this reconstruction. We could view the first three steps as an independent argument for (4), generating it by abductive reasoning, with (4) then figuring into the rest of what would be a valid argument, along with (3) and (5). From one perspective, this move just sweeps the invalidity under the rug—(4) would still be the consequence of invalid reasoning, although the reasoning wouldn’t be exposed to plain view. From another perspective, however, this move saves the argument from a quick and thoughtless death, since now we can evaluate (4) in light of the principles that apply to abductive reasoning, rather than merely dismissing the argument as a malformed deductive mess. The Principle of Charity enjoins us to adopt the latter view, as it keeps the argument alive for further analysis, and does not conflict with either the letter or the spirit of Benedetti’s remarks.

The third, fourth, and fifth steps imply the conclusion in conformity with modus ponens. Since (P3) and (4) must be conjoined before modus ponens can be applied, this part of the argument resembles that found in argument (C) above. This part of the overall argument is valid, but the argument as a whole is invalid. (Note that it could nevertheless be strong, if the abductive reasoning in the first part is inductively strong.)

(H): The final argument in the interview is best cast as an abductive argument. Given all the facts that Benedetti and Anabiarte cite, one is led to conclude that Fujimori acted badly with respect to the guerilla group. As we note in the theoretical discussion of abductive reasoning, the conclusion is an inference from the premises relative to some goal. Often this is the goal of explanation, but in this case, it is better to see the goal as the best judgment of Fujimori. Thus, if we were asked to issue a judgment based on the claims made, it would quite likely be that Fujimori acted badly. The conclusion is a normative judgment of Fujimori’s actions as described in (P5), given the first four steps as background information. Even so, the form of the argument remains the same.

An alternative to this reconstruction would be to cast this as a categorical argument, introducing a universal proposition expressing a rule that binds the killing of those who surrender to a negative moral judgment. This rule would then be instantiated in the case of Fujimori’s actions.

Content Analysis:

Each of these arguments contains questionable premises. Many contain steps that express Benedetti’s own value-laden opinions about situations in Mexico and Peru. For instance, (A) and (C) include predictions about humanity and Mexico, respectively, and while predictions can be strong, they are sensitive to a range of factors that are not mentioned in the arguments; as such, they should be regarded with some suspicion. The strength of (B), (D), and (G) depend on the truth of claims about Mexico that could be true, but are we to take Benedetti’s word for it? It is not clear that his credentials put the steps in these arguments past the point of criticism. Argument (E) is weak, for reasons cited above, although the conclusion may nevertheless be true. Argument (H) certainly seems strong, but are the facts correct? Are they beyond doubt? Do we have all the information about Fujimori’s actions? Perhaps we don’t, but perhaps we have information that establishes a pattern for him—if this were true, than ignorance of the specifics in this particular case might not dissuade us from drawing the negative conclusion. Of all the arguments, only (F) is beyond reproach given the information we have in our possession, as it concerns his own opinions and actions directly. While this is so, it is important to remain mindful of the fact that all of the other arguments but (E) could be compelling should it turn out to be the case that their premises are true. One who is more willing to take a chance on the veracity or knowledge of Benedetti than I am will be more inclined to trust these arguments as they are reconstructed above.

Context Analysis:

This is an interview, and interviews are often designed to solicit opinions and their justifications. In this case, the questions Anabiarte asks should lead us to expect arguments of this sort, and we find them in Benedetti’s responses. Interviews are interesting events, being highly conventionalized conversations. Since they are conversations, they are interactive and dialogical, although less so than a normal conversation. One should expect to find interviewer and interviewee working together to create arguments, and that is true in this case. The best example of this is (H), where Anabiarte offers a key premise in (P2).

Another important aspect of context analysis involves assessing the goals of the arguer. Here, it isn’t clear that Benedetti has an agenda or a set of goals, beyond responding adequately to Anabiarte and doing justice to his own beliefs. It would appear that his responses enable him to achieve these goals.

For identification of these arguments, go here.
For reconstruction of these arguments, go here.


II.2 Jonathan Alter on the Death Penalty

Formal Analysis:

Each of the main arguments that we have reconstructed are deductive. The arguments supporting the first main argument are both non-deductive arguments of the abductive type. The sub-argument supporting P1 in the second main argument is an inductive argument, while the sub-argument supporting P3 in that argument is deductive. We analyze each in turn.

(A): This argument is deductively valid. It is of the modus ponens form, with an antecedent that expresses an "and" proposition. As such, it is similar in form to argument (C) in the Benedetti interview. To get this argument, we have credited Alter with the implicit conditional premise (P3), which expresses a connection between the first two premises and the conclusion. We could have reconstructed the argument without that premise, in which case we would regard it as an abductive argument, with the conclusion serving as the best available explanation of the propositions expressed by the premises. One reason favoring a deductive reconstruction is that the conclusion is normative, that is, the conclusion speaks to what ought to be done; the first two premises, by contrast, are descriptive, specifying what is in fact done. The new element in the conclusion, then, changes the nature of the propositions expressed. Including that element in a premise, as we have done with P3, makes it clear that the context of the argument is essentially normative—Alter is not primarily interested in describing what is going on; rather, his primary goal is to prescribe a course of action that we should take vis-a-vis the death penalty.

(A.1): This is an abductive argument. In this case, the conclusion represents an inference to a yes or no response to the question of whether we execute innocent people in this country. The premises, if true, don’t guarantee this conclusion, so this is not a deductively valid argument as reconstructed. If we regard the premises as considerations that bear on the question, then the conclusion would appear to be the correct one, as the premises paint a picture that strongly suggests that we execute innocent people in the United States. P2' and P3' together by themselves suggest this, especially when you take into consideration the large number of executions in Texas. Unless there is independent reason to believe that Texas does something right that has eluded officials in Illinois, and Alter offers reasons for rejecting this, then the conclusion receives strong support from the premises. (Note that there is no significant difference in type between the conclusion and premises, and so the abductive reconstruction is a good choice here.)

There are two things that we should keep in mind, however, in assessing the non-deductive strength of this argument. First, it would be stronger if we weakened the conclusion so that it claimed only that we may be executing innocent people, or that it is very likely that we are doing this. Second, there may well be considerations that support a negative answer to this question that Alter is not supplying. It is not uncommon for this to happen, especially if the author has decided that the considerations (s)he cite are stronger than those that favor the other side, since in that case they feel justified in ignoring them. Since this is always a concern with arguments like these, it helps to have some opinion of the author’s record of bias formed through exposure to prior pieces (s)he has written.

(A.2): This is also an abductive argument, serving up a litany of considerations that incline us to infer that the judicial system does not ensure that the executed are always guilty. This abductive argument is similar to the preceding one, in that its premises are offered relative to the goal of answering a simple yes/no question, viz., whether or not the judicial system is complicitous in the execution of the innocent.

Once again, these considerations support the answer expressed by the conclusion. If these considerations were simple citations of procedural code or legislation, then the support would be quite strong, assuming that there are not considerations on the other side that mitigate this support. However, these premises do not serve up simple citations; in addition to facts about code and legislation, they also offer judgments, such as the one about an attorney’s competence in P3' and about what judges "tend" to do in P4'. (The second of these would be stronger if Alter provided evidence for this tendency, but the evidence is missing from the column.) This fact weakens the support offered to the conclusion, although not considerably, given that these judgments do not appear to be too much of a stretch. Another aspect of the argument that vitiates it a bit is the strength of the conclusion—it is a flatly negative response, and as such, it weakens the argument. The argument would be stronger with a more circumspect conclusion, but of course, Alter is not in the business of hemming and hawing about matters of this nature—columnists of that sort rarely stay employed long enough to get his kind of by-line.

(B): This argument is similar to (G) in the Benedetti interview, in that it combines a deductively valid argument with a non-deductive argument. Looking at steps 2' through C, we find a deductively valid argument of the modus ponens type, with 2' and P4' combining to affirm the antecedent. (This is structurally identical to argument (C) in the Benedetti interview.)

But the argument is not only deductive in character. In particular, P1' supports 2' inductively. This particular part of the argument is suspicious. We are told that most Texans believe that their state has wrongly executed someone, but why should we believe most Texans? It is unlikely that they have much more knowledge of what goes on with these cases than we do, and they surely are not privy to much information about death row inmates. Further, we are told in (B.1) that "most" means "nearly 60%", which is not an overwhelming majority, assuming we find no flaw in the poll itself.

(B.1): From a particular perspective, the conclusion might appear to simply restate the premise without the number. If this were true, the argument would be deductively valid, as we would simply be replacing "nearly 60%" with "most", a move that is justified by the meaning of the concepts associated with these terms. However, the premise introduces this percentage on the basis of a poll, and so this is better seen as an inductive argument. Polling data, drawn from a relatively small pool of Texans, is used to support a general conclusion about all Texans. This sort of inference can be strong if the pool is representative and if the polling techniques are not biased in any way. We are not given any of this information, and so we are not in a position to evaluate this claim. We might accept it for the sake of argument so as to see if Alter’s reasoning goes through, but we should be cautious about accepting too much that depends on this claim.

(B.2): This is a deductively valid argument of the modus ponens type. It is not obvious that this is so, but P1' and P2' do combine to imply that Bush has vetoed measures that could have slowed the pace of executions in Texas, and so they imply that the antecedent of P3' is true, thus leading us to C. Note that on this rendering, it is tempting to read P1', "If Texas had public defenders or "life without parole" sentences, then they would not lead the way in executions." P1' is best interpreted as a causal claim, but it is difficult to read it as a straight causal claim, since "because" does not introduce a positive causal factor. The absence of something is not a positive factor—it is causally relevant only if its presence would imply the absence of what now takes place. This is quite likely what Alter intends with that claim, but strictly speaking, it is not synonymous. For one thing, these might not have a big impact on what is a rather large lead in executions, thus leaving Texas’ lead intact. This sentence has what logicians call "modal force", and so is not truth functional and cannot be handled in any straightforward way with the tools introduced in the theory section. For a discussion of these issues, see Chellas and Cresswell.

Content Analysis:

Once again, these arguments include many claims that one should be suspicious about. In a short piece of this sort, the reader cannot expect to be given all the information that bears on the matter at hand, and that expectation is met here. However, there is a good bit of information supplied that is relevant, and Alter has succeeded in crafting the column so that the information leads in one direction, viz., toward the belief that innocent people are being executed in this country, and more specifically, in Texas. Once he has us headed in this direction, he uses the momentum to drive home two specific points: (a) we need a moratorium on executions in this country, and (b) we should be suspicious of George W. Bush’s ability to lead.

Close inspection of this information reveals that much of it is anecdotal, and anecdotal evidence, while illustrative, is by no means conclusive. There is (almost) always anecdotal evidence on the other side equal to or stronger than the evidence offered, and so it is not wise to place too much reliance on it. However, such evidence does make a column splashier, and its rhetorical value should not be underestimated by the critical thinker. To buttress the anecdotal evidence, Alter introduces relevant events in the recent past (viz., P3' in (A.1), P2' in (B.2)), (interpreted) facts about state and federal judicial policies (viz., P2' in (A.1); P1' through P5' in (A.2); P1' in (B.2)), and results of a poll (viz., P1' in (B.1)). When taken as a group, these considerations are compelling, but they do not constitute by any measure a knockdown argument for the two conclusions mentioned above.

This conclusion is reinforced by consideration of the specific premises. Consider, for instance, the premise that connects 2' and P4' to C in (B), viz., P3'. This premise certainly seems to be a reach. Clearly, Alter believes that there is an essential connection between leadership ability at the state or federal level and one’s actions on behalf of the innocent. While it is unlikely that we would be too hot to vote for someone who showed no regard for the innocent, it is not at all clear that Bush fits this profile. Further, leadership ability is complex and multifaceted, and it is much too simplistic to expect it to be reducible to a position on one issue alone, even one as central as the rights of the innocent. In addition to this claim, there are others that warrant something of a scowl, e.g., 2 in (B) and P1' in (B.2), to name two.

Beyond these points, there is also the fact that in choosing to exclude information, Alter could have excluded information that would significantly strengthen the opposite conclusion. Alter certainly knows this, and attempts to finesse this concern by noting that he is a staunch supporter of the death penalty, but even so, he has been persuaded by this reasoning. If anything, he seems to be saying, he would be biased in the other direction, but he resists that temptation so as to throw his weight behind a moratorium.

Context Analysis:

This is an editorial column. As such, it is a natural home to argumentation, and there is an ample supply of it in this case. There are different types of such columns, e.g., those that push a particular conclusion, as well as those that include a number of distinct parts designed to press a number of possibly unrelated conclusions. This column fits into the first of these groups, and so one should expect the column to work toward a single conclusion, or a small number of related conclusions, and that is what you find here. With a column of this sort, one should expect to find some help in identifying the primary argumentative goal in the title, and that is true in this case. A note of caution: syndicated columns can be edited to fit spaces in Op/Ed pages, and so central parts of the arguments in the pieces as written could be eviscerated in the reprinting, a fact that should encourage an even higher level of charity; nevertheless, in the end, critical thinking will boil down to you and the text you’re evaluating.

Does Alter succeed in advancing arguments that enable him to achieve his goal? This is the final question we must answer, and our answer will depend on how we evaluate form and content. There is nothing about the context that would appear to vitiate his efforts, as he does fit his arguments to his stated goal.

For identification of these arguments, go here.
For reconstruction of these arguments, go here.


II.3 Geckos and Sticky Feet

Formal Analysis:

There is one main argument in this essay, and it is deductively valid. The seven supporting arguments are also deductively valid, a fact that might seem odd given that this is a scientific report, and non-deductive argumentation is a hallmark of scientific reasoning. I address this concern in discussing the supporting arguments, which I treat as a group below.

(A): This argument is deductively valid, and is of the disjunctive syllogism sort. The author of the article, Kate Wong, lists six candidate explanations of the gecko’s marvelous ability, and then proceeds to indicate that four of those explanations are not in fact good candidates, given the evidence. Of the remaining two, she indicates that one is to be preferred over the other. Thus, five of the six candidates have been demoted to the level of implausibility, leaving one as the explanation of choice, viz., the explanation involving van der Waals forces. Formally, this is an impeccable argument, and it is located at the surface of the article, a fact that aids reconstruction.

(A.1)–(A.7): These are all deductively valid arguments of the modus tollens sort. I have chosen to represent them as such so as to capture the force necessary to drive the main argument discussed above. Their non-deductive character, however, remains intact. Indeed, the first premise in each of these supporting arguments is the result of a non-deductive argument, and in all cases the arguments for these premises appear to be confirmation arguments. The researchers sought to confirm hypotheses about the operation of gecko feet, only to find that the experiments falsified these hypotheses. In each case, then, the supporting arguments have a premise that represents the falsification of a hypothesis about the functional nature of gecko feet. In some cases, viz., P2 and P3, there are several such falsifications offered, a fact that strengthens the rejection of these hypotheses. P4 and P5, by contrast, are rejected only on the strength of one falsification each. This needn’t weaken them, however, since the nature of these falsifications is relevant to an assessment of the support they offer their conclusions in each case. However, when it comes to this sort of thing, more tends to be better.

Content Analysis:

This report is very brief, but it is also highly suggestive. Wong gives reasons for the falsification of hypotheses, but does not explain in much detail why these reasons imply their falsification. Further, nothing is said about the reason for preferring intermolecular forces over water adsorption, leaving us in the dark about P6 in (A). Wong claims that water adsorption has not been eliminated, but it is clearly not regarded as the frontrunner by the researchers. Most of the supporting arguments depend on information left implicit, information that would justify assertion of the bridge premise in each case (i.e., P2' in each supporting argument). In some case, what is left implicit is rather obvious, even to the untrained, such as with (A.7), (A.5), (A.4), (A.3), and (A.1). In others, such as (A.2) and (A.6), more scientific knowledge is required to appreciate the gap between what is assumed explicitly and what is concluded, and therefore, the truth value of the premises in these arguments.

Context Analysis:

This is a brief in a popular scientific publication, and so it should be read as a piece of science. The claims made and results described should be regarded as provisional, supported by evidence from which the scientist jumps to conclusions. Wong has made the provisional character of the conclusion clear, and has done a clear and effective job of indicating the nature of the scientific process by noting the various alternatives along with the reasons for their rejection. As the piece is intended to report the research of others, it must be understood as scientific journalism, and as such it succeeds. However, the facts of this piece reveal the arguments behind the results, establishing that even purely descriptive pieces can be argumentative.

For identification of these arguments, go here.
For reconstruction of these arguments, go here.


V.    Additional Resources

  1. Books

    1. Understanding Arguments, 6th ed., by Robert J. Fogelin and Walter Sinnott-Armstrong, Fort Worth, TX, Harcourt College Publishers, 2001, pp. 582 + xv.  A comprehensive introduction to critical thinking with several chapters devoted to various aspects of argument analysis, including deductive and non-deductive logic.

    2. Language, Proof, and Logic, by Jon Barwise and John Etchemendy, Stanford, CA, CSLI Publications, 2000, pp. 587 + xi.  An excellent introduction to symbolic deductive logic that also includes advanced topics in the later chapters.  This book comes with a CD-ROM that contains three excellent instructional programs:  Tarski's World, a program for teaching the semantics of first-order logic, Boole, a truth-table program, and Fitch, a program for teaching first-order deductive proofs.  For a class taught around this book, see Philosophy 202, taught every spring at the UI.

    3. Logic Primer, 2nd Edition, by Colin Allen and Michael Hand, Cambridge, MA, MIT Press, 2001, pp. 216.  An excellent short and accessible introduction to  symbolic deductive logic.  Recommended.  This is available through the UI library as an e-book.

    4. The Logic Book, 3rd Edition, by Merrie Bergmann, James Moor, and Jack Nelson, McGraw-Hill Higher Education, 1997, pp. 592.  An excellent and comprehensive introduction to symbolic deductive logic.

    5. Choice and Chance, 4th Edition, by Brian Skyrms, Wadsworth Publishing Co., 1999, pp. 218.  This is the standard introduction to inductive logic.  The first few chapters sets up the philosophical nature of inductive logic, and the last few supply a very accessible introduction to the probability theory necessary to an adequate understanding of this sort of logic.

  2. Websites

    1. An Introduction to Logic for Liberal Arts and Business Majors, by Stefan Waner and Steven R. Constenoble.  A useful tutorial in symbolic logic, complete with exercises.   

    2. First Order Logic Tutorial.  This site contains a quick but substantive introduction to symbolic logic, at a fairly high level.

    3. The PropCalc Work Place, by Robert G. Muncaster.  This is an excellent tool for exploring aspects of the propositional calculus.

    4. The Truth Table Work Place, by Robert G. Muncaster.  This is to truth tables what (3) is to the propositional calculus.

    5. Philosophy in Cyberspace: Logic and Philosophy of Science.  A collection of links to many sites on logic and critical thinking, at all levels.

    6. APA Online: Web Resources Software.  This site contains links to several logic software packages that teach logic at the beginning level.