A Basis for Legal Reasoning: Logic on Appeal
Mary Massaron Ross**
The training of lawyers is a training in logic. The process of analogy, discrimination, and deduction are those in which they are most at home. The language of judicial decision is mainly the language of logic.1
Logic has been central to legal education and thinking for many years. In the 1800s, when Christopher Columbus Langdell, dean of Harvard Law School, published the first modern casebook, the classical system "was premised on the view that law is a complete, formal, and conceptually ordered system that satisfies the legal norms of objectivity and consistency."2 The system was believed to be capable of "providing uniquely correct solutions or 'right answers' for every case brought for adjudication."3 It could "dictat[e] logically correct answers through the application of abstract principles derived from cases."4
The Modern Attack on Formalism and Logic
But modernist thinking weakened acceptance for the Langdellian view of the law. Justice Holmes reflected this modern skepticism about the role of logic in his oft-quoted statement that "[t]he life of the law has not been logic: it has been experience."5 Holmes was not alone in rejecting the idea that logic controls the outcome of judicial decisions. With the advent of the legal realism, some believed that "a judge decided which way he wanted a decision to go and then produced an elegant chain of reasoning to lead to his predetermined conclusion . . . ."6 Lawyers increasingly asserted that "a judge (or an academic) ‘constructs the materials to reach a desired result, and that the result is based on some real interest in winning a certain class of cases, either because they are significant to maintaining economic or political control or because they help solidify a certain ideological story that is helpful to maintaining domination.' "7 Judge Jerome Frank, for example, took the position that even when the rules are clear, they do not control the outcome.8 Adherents of the legal process school of jurisprudence likewise viewed law as less a matter of logic than of policy. In the legal scholars' view, decisions should be based not on the reasoned application of substantive theory but "on process values."9
Lawyers increasingly articulated the view that "the conscious process of legal reasoning is not really what accounts for a judge's decisions."10 One modern scholar, Derrick Bell, for example, wrote that law is "not a formal mechanism for determining outcomes in a neutral fashion—as traditional legal scholars maintain—but is rather a ramshackle ad hoc affair whose ill-fitting joints are soldered together by suspect rhetorical gestures, leaps of illogic, and special pleading tricked up as general rules, all in a decidedly partisan agenda that wants to wrap itself in the mantle and majesty of the law."11 Proponents of this view believe that "the legal system cannot be guided by rational thought; instead, its predictability derives from the unconscious mindsets of lawyers and judges."12 This trend to diminish logic as a basis of judicial decision-making is justified on the basis of its indeterminate nature. Proponents insist that legal reasoning "does not provide concrete, real answers to particular legal or social problems."13 Logic, they argue, leaves a range of choices.
Formalism is typically associated with "the logical, impersonal, objective, constrained character of legal reasoning."14 But an approach to legal reasoning that heavily emphasizes formal logic has been subject to attack as overly rigid and too abstract. Pragmatists advocate an approach by which the judge decides "the nonroutine case [by] . . . trying to come up with the most reasonable result in the circumstances, with due regard for such systematic constraints on the freewheeling employment of ‘reason' as the need to maintain continuity with previous decisions and respect the limitations that the language and discernible purposes of constitutional and statutory texts impose on the interpreter."15 As a result, rhetoric rather than logic has become a central tactic of persuasion.
Logic as an Advocacy Tool
Regardless of whether an appellate judge accepts logic as a determinant or adheres to a more pragmatic approach, as long as the rule of law requires like cases to be treated alike and judges to apply statutes and the constitution as written, logic remains an important part of any argument on appeal. And while the academic debates over jurisprudence have shifted from earlier times, advocates still need to employ persuasive tools that include both logic and rhetoric. Aristotle long ago taught that rhetoric was "an offshoot of logic, the science of human reasoning."16 And his comprehensive approach to persuasion remains a sound strategy for today. An advocate need not resolve the jurisprudential debates of scholars and judges over the grounds of judicial decision making in order to arrive at a persuasive strategy for arguing an appeal. But recognizing these debates has important ramifications.
Lawyers who believe that the unconscious mindset or the conscious evaluation of institutional strengths and policy considerations are determinants of judicial decisions will focus on rhetoric that tries to persuade the court on these terms. The belief that rhetorical tricks can help an advocate with a weak case prevail is not new. Cicero, for example, taught orators that if their cause was "discreditable," they should use the "subtle" approach to achieve a favorable result "covertly, through dissimilation . . . ."17 Aristotle, too, discussed the use of emotion in argument, explaining that "anger, pity, fear, and all other such and their opposites" could alter the judgments of listeners.18 Aristotle distinguished appeals to emotion (pathos) from the other modes of persuasion including appeals to reason (logos) and appeals to personality or character (ethos).19
According to Aristotle, "[r]hetoric is the counterpart of dialectics" or logic.20 He explained that "all men engage in them both after a fashion."21 But he emphasized that "speakers ought not to distract the judge by driving him to anger, envy or compassion . . . ."22 An opponent who engages in such practices can best be defeated by an approach that precisely reveals the logic (and illogic) of the arguments presented. Naming the rhetorical strategy and explaining why it serves as a distractor reminds the court that the decision should be based upon the application of reasoned, neutral principles to arrive at the correct result.
Despite the modern view that formal logic rarely controls the outcome, it may be, and often is, a critical element in the decision-making process. At the appellate level, reasoning remains a primary determinant of judicial decision-making. Thus, logic is critical on appeal. As a result, appellate advocates must learn how to best frame their arguments in the classic style of logic. Advocates who seek to prevail must test the logic of their arguments. Advocates must also search out any weakness in the logic of their opponent's argument. The ability to engage in such analytically precise and logical thinking is a hallmark of good advocacy. Like any skill, it requires practice and training. Study of books on rhetoric and logic is helpful. Aristotle, Cicero, and Quintillian all discussed logic and rhetoric in their writings—and what they had to say is surprisingly modern. Many newer books on logic and reasoning exist and also provide analytical tools for advocates when constructing or refuting a logical argument. Analysis of judicial opinions to lay bare the reasoning is also useful. Identifying the logical structure of an opponent's argument and then searching for structural or factual flaws is important. But few law schools directly teach logic. And few appellate briefs directly discuss it.
Inductive Reasoning Defined
Logicians divide logical reasoning into two categories: inductive and deductive. Inductive reasoning is based on generalizing from our existing knowledge or experience.23 The premises "of an inductive argument are not offered as conclusive evidence for the truth of their conclusions, but as evidence for the likelihood or reasonable probability of the conclusion's truth."24 Inductive reasoning generally takes one of two forms, inductive generalization or reasoning by analogy.
Inductive generalization involves drawing a general conclusion from a number of particular instances.26 The process of inductive generalization stems from science; scientists hypothesize certain outcomes and test them by repetition.27 If the scientist observes something to be true in every instance in a test, then he can infer that [it] is true in other instances as well.28 Inductive generalization is therefore based on the concept of probability. A "conclusion reached by inductive reasoning is not considered a truth; rather, it is a proposition that is more probably true than not."29
Inductive reasoning may also be based on analogy. Reasoning by analogy is based on the argument "that because the two examples are like in many ways they are also alike in one further specific way."30 In other words, the advocate claims "that since some percentage of one or more things (the sample) possesses a property, an inference can be made that some similar thing or things (the target) are likely to have that property as well."31 Analogies require a "relevantly similar example."32 Analogical reasoning is used to determine whether precedent is controlling.33 The "steps are these: similarity is seen between cases; next the rule of law inherent in the first case is announced; then the rule of law is made applicable to the second case."34 It is also used in numerous other ways in legal reasoning.
Reasoning by enumeration (inductive generalization from enumerated examples) and reasoning by analogy are similar. But in reasoning by enumeration, the argument is based on reviewing numerous instances of the same thing. For example, an inductive generalization might be reached about the color of horses by examining many horses. If one million horses are examined and none are white, one might conclude that horses are not white. In contrast, reasoning by analogy involves comparing different things that have some similar attribute. One might, for example, analogize a donkey to a horse and conclude that if no donkeys are white, then no horses are white. These examples make clear that the outcome of inductive reasoning is not necessarily true as a matter of logic; much depends on the comparison, the sample, and the breadth of the conclusion.
Testing Inductive Logic
When analyzing an inductive argument, the advocate should first "[i]dentify the two things being compared (A and B) and the property (P) that is being attributed to B in the conclusion."35 The advocate should then look for "the property (S) that is supposed to make A and B similar." To assess the strength of an inductive generalization, consider the size of the sample relative to the size of the target. If the analysis is based on a complete set, then the conclusion will be strong. But if a complete set is not used for the analysis, the conclusion may be weak. The advocate must test the strength of the conclusion by examining the sample's size and its representativeness. The advocate should also consider the strength and number of any counterexamples. In a search for counterexamples,36 look for prototypical cases, but also "referents close to the borderline of the concept, because many generalizations are true only of prototypical cases, not of atypical" ones.37
Evaluation of the strength of an analogy is based on similar considerations. The advocate should consider the size of the sample, the percentage of the sample that has the property, the similarities or positive resemblances, the relevance of the similarities or dissimilarities, the diversity within the sample, and the breadth of the conclusion.38 Analogies "do not require that the example used as an analogy be exactly like the example in the conclusion."39 Instead, the analogy requires "relevant similarities." Thus, the advocate should analyze whether the analogy is based on relevant or irrelevant similarities.
Whether an argument is based on the fallacy of a false analogy is often subject to debate. The analogy may be rejected if the comparison is based on irrelevant or inconsequential similarities or ignores dissimilarities.40 United States v. Leonard, 494 F.2d 955 (D.C. Cir. 1974) illustrates one such argument. A federal circuit court of appeals analogized paid informers and accomplices who give testimony against their cohorts to witnesses who are granted immunity. The comparison was based on the notion that all had an interest in testifying against another at trial beyond mere truth-telling.41 But the Wisconsin Supreme Court later characterized the analogy as "questionable," concluding that it lacked a "rational basis."42 A Maryland appellate court's attack on an analogy exemplifies another argument of this kind. In Conyers v. State, 691 A.2d 802 (1997), the appellant argued that the same rules should apply to in-court identification procedures as are applied to pretrial identifications. The court called this a false analogy because the policy concerns raised by overly suggestive pretrial identifications are absent in court where the identification is inherently suggestive since the defendant is always sitting at the trial table.43
These examples illustrate both the rhetorical strength of analogies and some strategies to refute them. The advocate can explain why the point of comparison is not relevant. Or the advocate can point out that there is no empirical or logical basis for the conclusion that the comparison is based on factors that are the same in the relevant aspect. These strategies allow the advocate to diminish the analogy's force as an argument by laying bare the logic or lack thereof that forms the underpinnings for the comparison.
The fallacy of faulty generalization may also mar a conclusion based on inductive reasoning.44 If a conclusion is based on inadequate evidence, then the generalization is faulty. The advocate should determine whether the evidence that has been used as the basis for the generalization is relevant, whether it is representative, and whether it is numerous enough to permit the conclusion.45 To the extent that evidence in support of a generalization is based on accepting authority of some kind, the advocate should evaluate whether the authority is biased or prejudiced, incompetent, or outmoded. In addition, the advocate should check to see if the authority has been inaccurately quoted, misinterpreted, or quoted out of context.46 Any of these can be a basis for undercutting the grounds for the generalization.
Deductive Logic Defined
Deductive reasoning, as Aristotle taught long ago, is based on the use of a syllogism to prove a conclusion on the basis of two other propositions.48 This kind of reasoning is "an act of the mind in which, from the relation of two propositions to each other, we infer, i.e., understand and affirm, a third proposition."49 The "truth of the conclusion is ‘contained within' the premises; the conclusion does not involve an assertion that ‘goes beyond' what is already stated, by implication, in the premises."50 Typically, deductive reasoning proceeds from a general proposition to a conclusion that is either a particular proposition or another general proposition. The truth of the conclusion is based upon whether the premises are true and whether the form of the argument is valid. An argument is valid when it "possesses a formal structure such that the premises, if true, provide conclusive grounds for the truth of the conclusion."51
Testing Deductive Logic
A "valid syllogism has no internal gap whatever; if the premises are true, the conclusion must be true; you cannot accept the premises and deny the conclusion without contradicting yourself."52 The advocate can therefore challenge a conclusion by attacking the truth of the premises or by attacking the form of the syllogism. False premises don't prove anything. And premises that are not logically related to the conclusion are not grounds for proof.
Testing an argument based on deductive reasoning requires the advocate to analyze the form of the argument. Syllogisms can take a number of forms, including a categorical one that is based on assertions about the relationship between classes. For example, the statement "all sparrows are birds" is a categorical proposition setting forth an assertion about the relation of the class of sparrows to that of birds. The categorical proposition can be affirmative or negative and includes a qualifier, such as all, none, some, or few. One logician explained that a valid syllogism might take the following form:
If p then q.
Alternatively, it can be stated in the negative:
If p then q.
Therefore, not p.54
Both of these are valid forms and the conclusions logically can be deduced if the premises are true. Syllogisms can also be hypothetical.
If p then q.
If q then r.
Therefore, if p then r.55
This chain is especially useful for analyzing cause and effect relationships. Syllogisms may also be disjunctive.
p or q.
Another form of syllogism is the dilemma. The form of that is:
p or q.
If p then r.
If q then s.
Therefore, r or s.57
Mary Massaron Ross, A Basis for Legal Reasoning: Logic on Appeal, was first published at 46 DRI For Def. 46 (No. 4, 2004). © 2004 DRI–The Voice of the Defense Bar. Reprinted with permission.
** Editor's Note: Mary Massaron Ross is a shareholder, and head of the appellate practice group, at the law firm of Plunkett & Cooney, P.C. in Detroit. She is a past chair of DRI's Appellate Advocacy Committee.
The article has been reprinted with minor modifications in formatting, including the use of footnotes for citations of authority. No changes have been made to the substance of the article or to the text or format of the citations.
1 Oliver Wendell Holmes, The Path of the Law, 10 Harv. L. Rev. 457 (1897) at 167 of The Essential Holmes (Richard A. Posner ed., 1992).
2 Gary Minda, Postmodern Legal Movements: Law and Jurisprudence at Century's End 1 (New York Univ. Press 1995).
3 Id. at 13.
5 Oliver Wendell Holmes, Jr., The Common Law 1 (1881).
6 J.G. Riddall, Jurisprudence 259 (2d ed. 1999).
7 Id., quoting Duncan Kennedy, The Structure of Blackstone's Commentaries, 28 Buff. L. Rev. 209 (1979).
8 Jerome Frank, Law and the Modern Mind (2d ed. 1963).
9 Minda, supra at 35; See also Henry M. Hart, Jr., & Albert M. Sacks, The Legal Process: Basic Problems in the Making and Application of Law (tent. ed. 1958) (Eskridge W. & Frickey P. eds., Foundation Press 1994).
10 Daniel A. Farber & Suzanna Sherry, Beyond All Reason: The Radical Assault on Truth in American Law 35 (1997).
11 Derrick Bell, Who's Afraid of Critical Race Theory? 1995 U. Ill. L. Rev. 893, 899-900.
12 Farber & Sherry, supra at 49.
13 David Kairys, Law and Politics, 52 Geo. Wash. L. Rev. 243, 244-247 (1984).
14 Richard A. Posner, Judicial Opinion Writing: Judges' Writing Styles (And Do They Matter?), 62 U. Chi. L. Rev. 1421, 1432 (1995).
15 Id. at 1432-1433.
16 Edward P.J. Corbett & Robert J. Connors, Classical Rhetoric for the Modern Student 32 (1999).
17 Cicero, Rhetorica Ad Herennium 13-21 (Harvard Univ. Press 1999).
18 Aristotle, The Art of Rhetoric 141 (Penguin Classics 1991).
19 Corbett & Connors, supra at 32.
20 Aristotle, supra at 66.
22 Id. at 67.
23 David Kelley, The Art of Reasoning 453 (1998).
24 Douglas Lind, Logic and Legal Reasoning 9 (2001).
26 Lind, supra at 15.
27 Ruggero J. Aldisert, Logic for Lawyers: A Guide to Clear Legal Thinking 6-2 (1992).
29 Id. at 6-6.
30 Anthony Weston, A Rulebook for Arguments 19 (3d ed. 2000).
31 Lind, supra at 10.
32 Weston, supra at 21.
33 See generally, Edward H. Levi, An Introduction to Legal Reasoning (1949).
34 Levi, supra at 2.
35 David Kelley, The Art of Reasoning 498 (3d ed. 1998).
36 Weston, supra at 10-18.
37 Kelley, supra at 458-459.
38 Lind, supra at 11-12.
39 Weston, supra at 21.
40 Corbett & Connors, supra at 69.
41 Id. quoted in Lind, supra at 98.
42 Linse v. State, 286 N.W.2d 554 (1980) in Lind, supra at 97-98.
43 Conyers, in Lind, supra at 102-103.
44 Corbett & Connors, supra at 68-69.
45 Id. at 68.
48 Aldisert, supra at 4-2.
50 Lind, supra at 7.
51 Id. at 111.
52 Kelley, supra at 239.
53 Weston, supra at 41.
54 Id. at 43.
55 Id. at 44.
56 Id. at 46.
57 Id. at 47.