Chapter Six: Analyzing
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
- 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.
- 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.
- 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.
- 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.)
- 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.
- 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
- 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.
- 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.
- 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
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
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
invalidremember 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
have given Benedetti (P2)without it, the argument is invalidbecause 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 Benedettis 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
implicitI 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 Benedettiperhaps he is well-known for his
veracitythen 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
twothis argument is practical in nature, given that it concerns Benedettis 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
validother 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 wouldnt 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 Benedettis 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
(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 Fujimoris actions as described in (P5), given
the first four steps as background information. Even so, the form of the argument remains
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 Fujimoris actions.
Each of these arguments contains questionable premises. Many contain steps that express
Benedettis 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 Benedettis 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 Fujimoris actions? Perhaps we dont, but perhaps we
have information that establishes a pattern for himif 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.
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 Benedettis 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 isnt 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
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 normativeAlter 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, dont 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 authors 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 attorneys 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 conclusionit 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
naturecolumnists of that sort rarely stay employed long enough to get his kind of
(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
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 Alters 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 factorit 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
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. Bushs 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 ones 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.
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 youre 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
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 geckos
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 neednt 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.
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.
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
- 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.
- 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.
- 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
- 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.
- 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.
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.
Order Logic Tutorial. This site contains a quick but
substantive introduction to symbolic logic, at a fairly high level.
PropCalc Work Place, by Robert G. Muncaster. This is an
excellent tool for exploring aspects of the propositional calculus.
Truth Table Work Place, by Robert G. Muncaster. This is to
truth tables what (3) is to the propositional calculus.
in Cyberspace: Logic and Philosophy of Science. A
collection of links to many sites on logic and critical thinking, at all
- APA Online:
Web Resources Software. This site contains links to
several logic software packages that teach logic at the beginning level.