Summer School on Law and Logic
European University Institute & Harvard Law School
16-20 July, 2012
Florence, Italy
Professors Brewer, Prakken, Rotolo, Sartor
Session 1.1.1
Introduction to basic concepts for the study of logic in legal argument
Course procedures and logistics
The web site for the course is here: https://lawandlogic2012.wordpress.com/
On the Welcome page you will see links for a page for each session of the course where you can find
slides, readings, exercises and some links to useful materials.
On the Contacts page are links to our web pages, and our email addresses.
Some background concepts for explaining the logic of legal rules and legal
arguments
Argument
From an epistemic point of view, an argument is a set of propositions (one or more),
called 'premises'1, that are offered to provide inferential warrant for another set of
propositions (one or more), called "conclusions." To say that one proposition, label it ''
(this is a premise in the sense just defined), provides inferential warrant for another
proposition, label it 'h' (this is a conclusion in the sense just defined), is to say that,
according to the argument presented, the truth of  would to some extent support the
claim that h is true. For example, the two premises 1 and 2 may be offered to provide
inferential warrant for the conclusion h in this argument:
1
2
All men are mortal.
Socrates is a man.
therefore
h
1
Socrates is mortal.
In this handout and at other times in this School we will use a convention (used often by philosophers of
language and logicians) for the use of single-quotation marks. According to this convention, singlequotation marks surround a word or phrase (or other text) so as to create a name for that word or phrase (or
other text). Thus for example, Harvard is a university and 'Harvard' is the name of a university and
''Harvard'' is the name of the name of a university. We will also continue to use a standard convention for
double-quotation marks, using them not to name a word or phrase (or other text) but actually to quote some
other source who uses that word or phrase (or other test). Thus, we will use "scare quotes" to refer to the
phrase 'scare quotes' because we would be quoting people who use scare quotes.
Session 1.1.1
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Logic and logical form
Logic is the study of the different modes of logical inference that different kinds of
arguments display. An argument's mode of logical inference (or, synonymously, its
logical form) is the evidential relation between the argument's premises and its
conclusion.2 In accord with this conception of logic, we may say that an argument's
logical form is the evidential relation between the argument's premises, i, and its
conclusion(s), hi.
Important note about the terminology here. The definition of 'logic' just offered
calls for a distinction between empirical and non-empirical evidentiary arguments.
Under this definition of ‘logic’, every argument is evidentiary because in every
argument premises are offered as providing some degree of evidentiary support for
conclusions. In a modus ponens argument ‘If P then Q and P, therefore Q’, for
example, premises ‘P’ and ‘Q’, taken together, provide evidential support for
conclusion ‘Q’ under this definition of ‘logic’, but it is not empirical evidential
support -- although a modus ponens can of course be used to establish empirical
propositions. (We shall examine this type of argument more closely in a later
session.)
The four modes of logical inference
In this course we will identify and refer to four "modes of logical inference" or "logical
forms": deduction, induction, analogy, and inference to the best explanation. As we shall
explain, these modes are distinguished from one another by the nature and structure of the
support that obtains between the premises of the argument and its conclusion.
There is a disagreement among analysts about whether all arguments, including legal
arguments, can fairly be represented by one or more of these four modes of logical
inference, or indeed even whether all four of these modes exist irreducibly one to another.
In this course, however, we will proceed as if deduction, induction, analogy, and
inference to the best explanation do exist as distinct modes of logical inference, allowing
that there may be differences among the four professors on this point. Since these modes
of logical inference – and the additional property of defeasibility, discussed below – are
features of arguments in many different domains (law, empirical science, morality, etc.),
it would be a mistake to refer to a special "logic of legal argument."
The four modes of logical inference we will examine in this course may be summarized
as follows. (Please note that the following descriptions are brief summaries only, and that
each mode of inference will be discussed more fully in upcoming sessions – for each
node of inference there is at least one upcoming session devoted to that mode of
inference.)
Cf. B. Skyrms, Choice & Chance 4 (1966) (“Logic is the study of the strength of the evidential link
between the premises and conclusions of arguments.”).
2
Session 1.1.1
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1. Deduction: In a valid deductive argument, it is logically impossible that the
premises should all be true while the conclusion is false. That is, the truth of the
premises of a valid deductive argument provides conclusive or incorrigible
evidence for the truth of its conclusion. ('Conclusive' and 'incorrigible' and their
counterpart terms 'non-conclusive' and 'corrigible' are, for our purposes,
synonymous.)
2. Induction: In an inductive argument, the premises provide corrigible, nonconclusive probabilistic evidential warrant for the conclusion (with probability
less than 1). There are two main forms: inductive generalization from
observation of several individuals, and inductive specification, the application of a
previously made generalization to an individual. We will devote a whole session
to induction (session 5.1.2). For now, a quick example of inductive generalization
is: because I've seen 1, 2, 3, . . . n swans that were white, I generalize that
all/most/x% of swans are white. An inductive specification applies a previously
made inductive generalization to an individual, often to make a prediction:
because all/most/x% of swans are white, the next swan I see is likely to be white.
As we shall see, there are notorious, still unresolved problems in establishing the
rational basis of induction, even though it is used constantly in empirical science
and serves as the foundation for a good deal of the reasoning that judges,
legislators, administrative agencies make about the worlds they adjudicate,
legislate, and regulate.
3. Inference to the best explanation ("IBE"; also called "abduction"): Inference to
the best explanation involves, as its name suggests, inference to an explanation of
some fact or set of facts. In this argument, a statement of the phenomenon (or
phenomena) to be explained and the putative explanation both appear as premises
of the argument and the explanation itself is the argument's conclusion. Although
this mode of inference has been recognized by many philosophers, perhaps for
centuries, it came into prominence in the modern period due to the work of the
great American logician, philosopher, and mathematician Charles Sanders Peirce
(1839–1914). Peirce called it 'abduction', but both 'abduction' and IBE refer to the
same mode of logical inference. Many scholars who study IBE, including Peirce,
believe that all instances of IBE instantiate the deductively fallacious argument
"affirming the consequent" (a fallacy we shall discuss in an upcoming session3).
Unlike these scholars, and for reasons we shall explore in Session 4.2.2, I (SB)
believe that some IBE explanations can fairly be explained as resting on valid
deductive inferences. Consider. for example, an IBE that explains how a pawn in
chess can appear on the same column as a pawn on the same “team.” The
premises in that IBE seem to provide conclusive, incorrigible evidence for the
3
Here is an example of the fallacy of affirming the consequent:
1
If there is a contract then there is an agreement.
2
There is an agreement.
therefore
h
there is a contract.
Session 1.1.1
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truth of their conclusions, which they would not do if they instantiated a
deductively invalid argument. Some other IBE arguments, such as many of those
offered in empirical science (or in evidence law or indeed in everyday life)
provide only corrigible, non-conclusive evidence (probabilistic warrant with
probability less than 1). Consider, for example, the IBE's that would explain the
cause of an accident, or a pain in one's foot, or the cause of an illness.
4. Analogy: In an analogical argument, one reasons that because two or more items
share some characteristics, one can infer that they share an additional
characteristic that is of particular interest to the reasoner. Within analogical
inference IBE operates to discern the pattern relating the sharing of some
characteristics and the inferred sharing of an additional characteristic that is of
interest to the reasoner. In analogical inference examples are used as heuristics to
convert examples into rules. For some analogical arguments the premises provide
incorrigible evidence for the truth of their conclusions, while in other analogical
arguments, such as those used in empirical science, the premises provide only
probabilistic evidential support.
Two properties of arguments: defeasibility and indefeasibility
Some arguments are defeasible and others are indefeasible. No argument is both
defeasible and indefeasible. Here are two definitions of 'defeasibility' that express the
same basic idea regarding what the property of defeasibility is:
Defeasible argument
Definition 1: A defeasible argument from premises 1-n to conclusion h is one in
which it is possible that the addition of some premise(s), n+1, to 1-n, can
undermine the degree of evidential warrant premises that 1-n provide for h.
Definition 2: If a conclusion h can be conclusively derived from a set of premises
S1, then h can also be derived from whatever set S2 results from the addition of
further premises to S1 (from whatever premises constitute set S2 such that S1 is a
subset of S2). On the contrary, when one draws defeasible inferences from a set of
premises S1,it may happen that, by adding further premises to S1, one obtains a
set S2 which does not entail some conclusions one could derive from S1 alone.
Defeasible reasoning schemata license non-monotonic inferences: their
conclusions may need to be abandoned when new information is.
Here is an example of the dynamics of defeasible argument. Consider evidence n (more
precisely, evidentiary propositions) offered as argumentative support for hypothesis h, as
follows:
Session 1.1.1
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(1) Jones confessed to shooting Smith
(2) Each of five witnesses testified that he or she saw Jones
shoot Smith
(3) Jones' fingerprints were found on the gun recovered at the
scene of Smith's shooting.
Therefore, (h) Jones shot Smith
(1) If 1, 2, and 3 were all true, how strong would they be as evidence for the hypothesis h?
(2) Now suppose that the whole set of 1 through 7 are true (including, that is, 1, 2, and 3). In that
case, with the larger set of propositions as a background, how strong would 1, 2, and 3 be as
evidence for h?
4
Jones was beaten by the police and ordered to confess.
5
Each of the five witnesses was bribed by the prosecutor to testify that he
she saw Jones shoot Smith.
6
Fingerprint evidence is reliable only 40% of the time.
7
The technicians in laboratory to which the gun was sent for
fingerprint analysis were both incompetent and corrupt.
(3) In the example of Jones and Smith, the argument from 1, 2, and 3 as premises to the hypothesis
h is defeasible or indefeasible?
Consider two more examples:
The Monge case
In Monge v. Beebe Rubber Company, 316 A.2d 549 (New Hampshire, 1974), the
Supreme Court of New Hampshire changed New Hampshire's very long established
precedent rule for "employment at will" contracts. We may represent that rule as follows:
1: Every employment contract that specifies no duration is terminable at will by
either party.
In the Monge case, plaintiff Monge was a female employee in the defendant factory who
had been fired, and who claimed, in an action for breach of contract against the factory,
that she was fired because she refused to date the factory foreman. If the Monge court had
applied rule 1, it should have reasoned as follows, using the deductive inference rule
known as "modus ponens" (we discuss this inference rule in the next session of this
Course) to conclude that the defendant did not breach the employment contract with Olga
Monge, even if she was fired as an act of (what today would be characterized as) sexual
harassment:
Session 1.1.1
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1: Every employment contract that specifies no duration is terminable at will by
either party.
2: If an employment contract is terminable at will by either party, then
termination by either party is not a breach of contract.
3: Olga Monge and Beebe Rubber Company signed an employment contract that
specified no duration.
Therefore,
h:
The employment contract is terminable at will by the Beebe Rubber
Company and termination of the contract by the Beebe Rubber Company
is not a breach of contract.
The Monge court did not, however, reason in this way. The court found that, as a matter
of fact,4 there was sufficient evidence for a reasonable jury to conclude that the following
proposition was true:
4 The Beebe Rubber Company fired Olga Monge in malice because she refused
to give into the sexual advances of the factory foreman.
Taking into account the sufficiently-evidenced truth (in the court's view) of proposition
(4), the Monge court modified the rule (1), in effect adding this qualification:
(5) Every contract that specifies no duration is terminable at will by either party
unless the employer terminates the contract in bad faith, malice, or
retaliation.
How should we explain the court's shift from 1 to 5? One way would be to explain it as
the court's decision to change (by logically narrowing) a deductively applicable rule, just
as a football association could change the rule 'every time the ball enters the goal in legal
play, the scoring team receives 1 goal' to the rule 'every time the ball enters the goal in
legal play, the scoring team receives 2 goals'. On this view, the shift in rules requires no
explanatory apparatus other than (i) the logical form of deduction and (ii) a decision by
the requisite authority to change that rule to a different deductively applicable rule.5 On
this view, the new deductively applicable rule after the Monge decision is:
4
This kind of factual predicate is what philosophers of language sometimes refer to as a "thick fact,"
namely, a predicate that has empirically discernible criteria but also a strong value component, such as the
terms, familiar in legal discourse, 'malice', 'reasonable' and 'unconscionable'.
5
For discussion of this view, referred to as the "deductive punctuated equilibrium" model, see Brewer, On
the Possibility of Necessity in Legal Argument: A Dilemma for Holmes and Dewey, 34 John Marshall L.
Rev. 9, 10-11 (2000). That model is opposed to a view, very influentially advanced in American
jurisprudence by jurist Oliver Wendell Holmes, Jr., and philosopher John Dewey, that the article
Session 1.1.1
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(6)
If
the employer terminates an employment contract that specifies no duration
and
the termination is in bad faith, malice, or retaliation
then
the employer breaches the contract.
But is that an adequate explanation of rule change in a case like Monge? Perhaps we
need additional explanatory tools, specifically, a sensitive analysis of the property of
defeasibility and not just the dynamics of deduction and decision. We will explore this
question in session the next session, 1.1.2, as well as in session 3.2.1. (See also the
discussion in Sartor, Defeasibility in Legal Reasoning, section R, "Overcoming legal
defeasibility?")
Here's another well-known example to consider regarding defeasibility, this one not in the
domain of legal argument but in the domain of epistemology.
"Gettier" examples
1: Jones believes that proposition P is true
2: Proposition P is true
3: Jones is justified in believing that P is true.
Therefore,
h: Jones knows P
Is the inference from premises 1, 2, 3, to h a valid deductive argument? Is it a defeasible
argument? A great many philosophers have assumed that the argument from -- a version
of which was first presented by Plato, and later by Bertrand Russell, and still later by
Edmund Gettier (this type of problem now bears his name) is indeed defeasible.
characterizes as "defeasibility anti-deductivism" – namely, the view that all legal arguments are defeasible
and thus, perforce (by the definition of 'defeasibility') no legal argument is deductively valid.
Session 1.1.1
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The definition of 'defeasible' allows us to identify two properties that an argument can
have: defeasibility and indefeasibility. The only type of argument that is not defeasible
(that is, the only type of argument that is indefeasible) is a valid deductive argument.
As we shall discuss in session 4.2.2 (and as was suggested above) some inferences to the
best explanation are defeasible (they have the property of defeasibility) while others are
not. The same is true of arguments by analogy, as we shall discuss in session 3.2.2.
Unique among the four modes of logical inference, valid deductive arguments are
inherently indefeasible, and inductive arguments (whether inductive specification or
inductive generalization) are inherently defeasible. Note that we will not treat defeasible
arguments as a distinct mode of logical inference, but rather as a property of arguments.
The enthymeme
The methods we develop for analyzing the logic of legal argument analysis are designed
to handle a familiar problem in the evaluation of non-formal legal rules and non-formal
legal arguments: they are very often enthymematic. What we mean by the phrase 'nonformal' is precisely that the logical structure of the rule or argument is not explicit. Of
course, in another sense, legal rules are highly "formal."
An enthymeme is any rule or argument (deductive, inductive, abductive, or analogical),
whose logical form is not explicitly clear from its original mode of presentation
(presentation, for example, in a judicial opinion or a lawyer's brief).
Note that we identify two types of enthymeme, one of which we will refer to with the
phrase 'rule-enthymeme' and the other of which we will refer to with the phrase
'argument-enthymeme'.
Rule-enthymeme
Here is an example of a rule-enthymeme:
(R) Any person who knowingly transports stolen property over state lines is guilty
of a felony.
Is R equivalent to R1 or to R2?
R1 Any person who transports over state lines property that he knows is stolen is
guilty of a felony.
R2 Any person who knows that he is transporting over state lines property that is
stolen is guilty of a felony.
Note that under R2 a person can be guilty of the felony even if he doesn't know that the
property is stolen, whereas under R1 he is not guilty unless he knows that it's stolen
(indeed, under R1 he need not even know that the stolen property has been taken over
Session 1.1.1
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state lines). This is a particularly obvious example of a rule-enthymeme because R itself
is ambiguous.6
But the phenomenon of rule-enthymemicity is far more pervasive than rule-ambiguity.
Consider this statement by the court in the Monge case:
(Monge rule-enthymeme) "We hold that a termination by the employer of a
contract of employment at will which is motivated by bad faith or malice or based
on retaliation is not the best interest of the economic system or the public good
and constitutes a breach of the employment contract."
This is a rule-enthymeme because in the form in which it literally appears in the opinion,
the exact logical elements and logical structure of the rule are not explicit.
We introduce another term that identifies the process of attempting to offer a fair formal
representation of a rule-enthymeme, a process we will refer to as "rulification."
Here is one effort to rulify the Monge rule-enthymeme7:
IF
[B]8 there is a termination by the employer of a contract of employment at
will which is motivated by bad faith
OR
[M] there is a termination by the employer of a contract of employment at
will which is motivated by malice
OR
[R] there is a termination by the employer of a contract of employment at
will or based on retaliation
THEN
[I] the termination is not the best interest of the economic system or the
public good and constitutes a breach of the employment contract.
6
The ambiguity concerns what philosophers of language refer to as "opaque contexts" in which
propositions occur, such as "knows that," "believes that," "is necessary that" and many others that occur in
law. For good discussion see R. Rodes and H. Pospesel, Premises and Conclusions (1997), chapter 6,
"Intensional Contexts."
7
8
We will discuss explicitly the method of representing rules in the format used at the text for this note.
As we will see in the session 1.2.2, these are "propositional variables" in the system of propositional logic.
Session 1.1.1
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AND
[E] there is a breach of the employment contract.
Even the shift from the court's 'We hold that' to 'if' . . . 'then' is a move from the
enthymematic form of the rule to a form whose logical form is clear. 'We hold that'
seems grammatically to be an assertion, but it is not explicitly a conditional, which is the
logical form of rules. We interpret the court to be declaring a rule, knowing what we
know about the context of the statement and what courts do.
A few more terms are helpful here to understand rule-enthymemicity: the logical form of
a rule consists of two components:
the logical elements of the rule (represented as 'B', 'M', 'R', and 'E' above)
the logical structure (represented by the logical operators 'If . . . then' and 'or'
above – the logical structure of this rulified rule is three "disjointly sufficient
conditions," namely B, M, and R, for two "jointly necessary" conditions, I and E.
(We will explain these terms in session 1.2.2.)
We have just noticed that the grammatical form of the court's statement in Monge does
not make it explicitly clear that they are offering a rule. We need our knowledge of the
context of the utterance to interpret the enthymematic natural language statement by the
court into its logical form of a rule. There is another aspect of the rule as the Monge court
stated it makes it enthymematic. When we rulify, should we (as we have done above)
treat this part of the enthymeme as part of the rule the court endorses?
". . . is not the best interest of the economic system or the public good . . . ."
Or might that part of the enthymeme not be regarded as a rule-element and instead as a
statement of the court's rationale for the rule it adopts? This unclarity is potentially
problematic, since it's arguable that a subsequent decision by the same court, the Howard
case (also the Supreme Court of New Hampshire but with membership different from the
composition of the Monge court) exploited this unclarity substantially to narrow the
Monge rule. (We will examine Howard's treatment of Monge in Session 3.2.2, the
session on analogy and disanalogy.)
Although it is unusual in the literature to find enthymemicity attributed to rules, there
seems to be no good reason not to do so, for the reasons and with the illustration just
offered. Much more common in the literature is to find the property of enthymemicity
attributed to arguments, and enthymemicity is indeed an important property of many
arguments, and many many legal arguments. 9
9
For discussion of the evolution of logician's use of the term 'enthymeme' as a property of arguments, see
Brewer, Exemplary Reasoning: Semantics, Pragmatics, and the Rational Force of Legal Argument By
Analogy, 109 Harv. L. Rev. at 984 ff.
Session 1.1.1
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Argument-enthymeme
Here is an example of an argument-enthymeme. Suppose a judge writes in an opinion
resolving a contracts dispute:
"The plaintiff was an employee-at-will, so she could be fired for any reason or no
reason at all." (Compare the Monge case, discussed further below.)
This might be represented as a premise 1 that provides inferential warrant for conclusion
h:
1: The plaintiff was an employee-at-will.
therefore,
h: The plaintiff could be fired for any reason or no reason at all.
Is that a valid deductive argument? By definition, a valid deductive argument is an
argument in which, whenever all the premises are true, the conclusion must be true.
Taken as literally quoted, the argument seems not to be valid. By its literal terms the
argument provides no reason to believe that every employee that is an at-will employee
can be fired for any reason or no reason at all. Without more, it is conceivable that some
types of employee-at-will can be fired only for cause. (In American contract law, the
limitation on the employer's right to fire the employee only "for-cause" is the opposite of
the freedom the employer enjoys to fire an employee "at-will," that is, "for any reason or
no reason at all". We will offer a formal modeling of this kind of opposition in the
discussion of the work of American theorist Wesley Hohfeld and "deontic" logic, in
session 4.1.2.)
But perhaps we conclude that the argument, properly interpreted, is not deductively
invalid. Perhaps we think of ourselves as interpreters of the judge's argument who seek to
give a fair formal representation of this argument which is presented in the non-formal
setting of a judicial opinion. Perhaps we believe that the judge was using a shortcut and
didn't feel the need to state explicitly that he was assuming -- and assuming that his
interpreters would know that he was assuming -- that all employees-at-will can be fired
for any reason or no reason at all. If we believe that the judge offering this argument
from 1 to h was relying on the unstated but assumed premise, 'All employees-at-will can
be fired for any reason or no reason at all', then we would conclude that the best way to
interpret the judge's argument is as follows:
0:
1:
All employees-at-will can be fired for any reason or no reason at all.
The plaintiff was an employee-at-will.
Session 1.1.1
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therefore,
h:
The plaintiff could be fired for any reason or no reason at all.
-- which is a valid deductive argument. (This is another instance of "modus ponens"
argument.) In this example of how we might interpret the judge's argument, we conclude
that the true logical form of the argument (that premises 0 and 1 provide inferential
warrant for h) was not explicitly clear from the way in which it was originally presented;
at first glance it seemed like the argument was that 1 by itself provided the inferential
warrant for h. But, on second glance, we might judge that the argument is an enthymeme,
an argument, as defined above, whose logical form is not explicitly clear from its original
mode of presentation but whose proper logical form is discernible by a fair formal
representation.
Note that we must give some attention to the circumstances under which we think we, as
interpreters of arguments, are warranted in treating them as enthymemes.10 After all, if
we add the right premise, every argument could be interpreted as a valid deductive
argument. But surely we don't believe that every argument is a valid deductive argument
or indeed is a deductive argument at all – some are inductive, some analogical, some
abductive.
Here is another example that calls attention to the need to be careful when interpreting
enthymemes and attempting to give a fair representation of them in explicit logical form.
Philosophers have long offered this argument as the paradigm of a valid deductive
inference.
1
2
All men are mortal.
Socrates is a man.
Therefore,
h
Socrates is mortal.
This does indeed seem to be a valid deductive inference, for it does seem that in any
possible world in which 1 and 2 are true h must also be true. But consider what kind of
justification there could be for the first premise, ‘All men are mortal.’ Surely it rests on
an inductive generalization (highly confirmed, to be sure). Might one not fairly represent
the “Socrates syllogism” not as a deductively valid inference but as an inductive
specification, that is, an application of an inductive generalization to an individual, where
the major premise is not assumed or known to be a true universal generalization, which
10
Etymologically, the proper transliteration of the Greek plural for 'enthymeme' (ἐνθύμημα) is
'enthymemata' (ἐνθυμήματα). But since that is unwieldy to pronounce, a common convention is now to
make 'enthymemes' the plural of 'enthymeme'. The adjectival form is 'enthymematic', which is still a
mouthful but we will stick with it.
Session 1.1.1
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inductive generalizations are incapable of producing? What criteria should we use? As
analysts of the logic of legal argument we try to be sensitive to such questions. (We
discuss inductive generalization and inductive specification in session 5.1.2.)
Monge vs. Beebe Rubber Company: illustration of four (or 3.5) modes of
logical inference in legal argument
Suppose an employee of a private business in New Hampshire, who had been hired for an indefinite
period of time, brought a breach of contract claim in 1970, claiming he had been fired for wearing
her hair too long. As best you can tell from the Monge case, would that employee have a cause of
action for breach of contract under state law?
Suppose an employee of a private business in New Hampshire hired for an indefinite period of time
was fired for wearing blue shirts, also in 1970? As best you can tell from the Monge case, would that
employee have a cause of action for breach of contract under state law?
Suppose that a black employee of a private business in New Hampshire in 1970 hired for an
indefinite period of time was fired because the employer basically didn't like black people? As best
you can tell from the Monge case, would that employee have a cause of action for breach of contract
under state law?
Suppose that a female employee of a private business in New Hampshire hired for an indefinite
period of time was fired for not agreeing to date the foreman? As best you can tell from the Monge
case, would that employee have a cause of action for breach of contract under state law?
The basic logical structure of a legal claim
(i) In effect, the plaintiff is asserting, 'I, plaintiff, can sufficiently prove (under the
applicable burden of persuasion11) a set of facts, call them F1 and F2 and F3 and . .
. Fn '
(ii) In effect, the plaintiff is also asserting, 'There is a valid legal rule in this
jurisdiction, that says, "When F1 and F2 and F3 and . . . Fn are sufficiently proven
to be the case, then legal consequences, call them C, follow.'
That is, the plaintiff's argument is as follows:
1
All instances of facts F1 & F2 and F3 & . . . & Fn get legal
consequence C
2
If there is sufficient proof12 of F1 & F2 and F3 & . . . & Fn then F1
11
In U.S. law, the burden of persuasion in most civil trials (such as trials involving disputes in contracts,
torts, property) is "preponderance of the evidence." That means that the party who bears the burden of
persuasion must persuade the trial judge or jury by a preponderance of the evidence. In criminal trials, the
burden of persuasion is "beyond a reasonable doubt."
12
Note that "sufficiently prove" means proof under the applicable burden of persuasion, also referred to as
the "burden of proof."
Session 1.1.1
page 14
& F2 and F3 & . . . & Fn
3
There is sufficient proof of F1 & F2 and F3 & . . . & Fn
therefore,
h1
F1 & F2 and F3 & . . . & Fn
therefore
h2
I'm entitled to legal consequence C.
The basic logical structure of plaintiff Monge's legal claim
1
There's a valid legal rule in this jurisdiction that says or implies
that if I can sufficiently prove that I was fired for not agreeing to date the
foreman (that is, if I can prove F1 & F2 and F3 & . . . & Fn), then specific
legal consequences follow, namely, there's been a breach of contract (C)
2
I can sufficiently prove that I was fired for not agreeing to date the
foreman.
Therefore,
h
There has been a breach of contract, with the further consequence
that I am entitled to damages.13
If plaintiff Monge filed this lawsuit for breach of contract, what rule would you invoke if you were
counsel for the defendant?
13
In this representation of plaintiff Monge's argument we treat 1 and 2 as premises for the conclusion h.
But note that a very common feature of argument in general, including legal argument, is the "chaining" of
arguments, in which what is a premise relative to one set of propositions is a conclusion relative to another.
Thus there might well be an argument whose conclusion is
There's a valid legal rule in this jurisdiction that says or implies that if I can sufficiently prove that
I was fired for not agreeing to date the foreman (that is, if I can prove F 1 & F2 and F3 & . . . & Fn),
then specific legal consequences follow, namely, there's been a breach of contract (C)
-- and then, in the chain of arguments, this in turn serves as a premise, which is how we have used our " h" terminology to represent in in the text to this note. For discussion of the "double duty" of evidence and
hypothesis in the context of reasoning about evidence, see Brewer, Logocratic Method and the Analysis of
Arguments in Evidence, p. 196 (example of representation of a chain of arguments in which there is "double
duty" of propositions, serving as hypothesis of evidence relative to one set of premises and evidence for
hypotheses relative to another set of premises that come later in the chain.)
Session 1.1.1
page 15
Given what we've observed about the apparent state of the law in 1970, could how could the plaintiff's
lawyer claim that there was a valid rule of the sort that the plaintiff claimed, (claim (1) in the
reconstruction of the plaintiff's argument above) in or around 1970, when this action arose?
A note on the relation between the logic and the rhetoric of legal argument
The judge in the majority opinion in Monge mentions these facts about the plaintiff in the
case:
"Plaintiff, before coming to this country in 1964, was a school teacher in Costa
Rica. She came to New Hampshire in 1965, and was attending college from 7 to
10 o'clock five nights a week to qualify to teach here. She used the money she
*131 earned from her employment with the defendant on the night shift beginning
at 11 o'clock for her college expenses. She was employed by the defendant in a
union shop and joined the union as required after her employment, thereby
becoming subject to the seniority and other rules of the union contract. After
working without incident on the conversion machine for about three months, she
applied to fill an opening on a press machine at higher wages. She testified that
her foreman told her that if she wanted the job she would have to be ‘nice’. She
got the job at $2.79 per hour and claims that her foreman then asked her to go out
with him, which she refused to do because she was married and had three
children. After working on the press machine for about three weeks, the machine
was shut down and she was put on a degreaser machine at $1.99 per hour. Her
overtime was taken away, although no one else's was. She testified that when she
told her foreman she needed overtime money he told her she could sweep floors.
She agreed to do this and claims the foreman also made her clean the washrooms
and ridiculed her."
In Part 2 of his treatise Rhetoric, Aristotle says this:
"Rhetoric may be defined as the faculty of observing in any given case the
available means of persuasion. This is not a function of any other art. Every other
art can instruct or persuade about its own particular subject-matter; for instance,
medicine about what is healthy and unhealthy, geometry about the properties of
magnitudes, arithmetic about numbers, and the same is true of the other arts and
sciences. But rhetoric we look upon as the power of observing the means of
persuasion on almost any subject presented to us; and that is why we say that, in
its technical character, it is not concerned with any special or definite class of
subjects."
[Translated by W. Rhys Roberts, http://classics.mit.edu/Aristotle/rhetoric.1.i.html]
Do you think there are elements of rhetoric (as defined by Aristotle) in this part of the judge's
opinion? Why do you think the judge mentions these facts about the plaintiff – is he making a special
law for immigrant mothers from Costa Rica who go to college and work in factories?

Before coming to the United States in 1964, was a school teacher in Costa Rica.
Session 1.1.1
page 16

She came to New Hampshire in 1965

She attended college from 7 to 10 o'clock five nights a week to qualify to teach
here.

She used the money she earned from her employment with the defendant on the
night shift beginning at 11 o'clock for her college expenses.
More generally, will we want to be sensitive to the interaction of rhetoric and logic in legal
arguments.
Four skills we will develop (or improve) in this course
(1) Skill with precise analysis of the logical structure of legal rules (such as rules in the law of
contracts, torts, criminal law) – moving from the enthymematic form of legal rules into a fair
representation of their logical structure.
(2)Skill with precise analysis of the logical structure of legal arguments – also moving from
the enthymematic form of legal arguments into a fair representation of their logical structure
Recall that an argument is a set of propositions in which one or more premises are offered
to support one or more conclusions. Consider some examples of argument-enthymemes.
(i)
(a) Do the following paragraphs from the Monge opinion present an argument (as
defined above)?
(b) If so, exactly what are the premises and conclusions of the argument?
(c) How strong is the support that the premises provide for the conclusion?
"Plaintiff sued for breach of an employment contract for an indefinite
period of time. The employer has long ruled the workplace with an iron
hand by reason of the prevailing common-law rule that such a hiring is
presumed to be at will and terminable at any time by either party. 53
Am.Jur.2d Master and Servant, s 43 (1970); 9 S. Williston, Contracts s
1017 (Jaeger ed. 1967); Restatement (Second) Agency s 442 (1958); see
Blumrosen, Seniority and Equal Employment, 23 Rutgers L.Rev. 270
(1969). When asked to reexamine the long-standing common-law rule of
property based on an ancient feudal system which fostered in a tenancy at
will a relationship heavily weighted in favor of the landlord, this court did
not hesitate to modify that rule to conform to modern circumstances.
Kline v. Burns, 111 N.H. 87, 90, 276 A.2d 248, 250 (1971); Sargent v.
Ross, 113 N.H. -, -, 308 A.2d 528 (1973).
Session 1.1.1
page 17
"The law governing the relations between employer and employee has
similarly evolved over the years to reflect changing legal, social and
economic conditions. 3A A. Corbin, Contracts s 674 at 205, 206 (1960). In
this area ‘(w)e are in the midst of a period in which the pot boils the
hardest *133 and in the process of change the fastest.’ Id. Although many
of these changes have resulted from the activity and influence of labor
unions, the courts cannot ignore the new climate prevailing generally in
the relationship of employer and employee. See Comment, ContractsTermination of Employment At Will-Public Policy May Modify
Employer's Right to Discharge, 14 Rutgers L.Rev. 624 (1960); Blumrosen,
Employee Discipline, 18 Rutgers L.Rev. 428, 431-33 (1964)."
(ii) Exercise:
(a) Do the following paragraphs from the Monge opinion present an argument (as
defined above)?
(b) If so, exactly what are the premises and conclusions of the argument?
(c) How strong is the support that the premises provide for the conclusion?
"In all employment contracts, whether at will or for a definite term, the
employer's interest in running his business as he sees fit must be balanced
against the interest of the employee in maintaining his employment, and
the public's interest in maintaining a proper balance between the two. See
Note, California's Controls On Employer Abuse of Employee Rights, 22
Stanford L.Rev. 1015 (1970). We hold that a termination by the employer
of a contract of employment at will which is motivated by bad faith or
malice or based on retaliation is not the best interest of the economic
system or the public good and constitutes a breach of the employment
contract. Frampton v. Central Indiana Gas Co., 297 N.E.2d 425
(Ind.1973); see Petermann v. International Brotherhood, 174 Cal.App.2d
184, 189, 344 P.2d 25, 27 (1959); Blades, Employment At Will v.
Individual Freedom: On Limiting the Abusive Exercise of Employer
Power, 67 Column.L.Rev. 1404, 1418, (1967). Such a **552 rule affords
the employee a certain stability of employment and does not interfere with
the employer's normal exercise of his right to discharge, which is
necessary to permit him to operate his business efficiently and profitably.
The sole question on appeal is whether there was sufficient evidence to
support the jury's finding that defendant, through its agents, acted
maliciously in terminating plaintiff's employment. It is the function of the
jury to resolve conflicts in the testimony, Kilfoyle v. Malatesta, 101 N.H.
473, 475, 147 A.2d 111, 113 (1958); and the law is settled that a jury
verdict will not be disturbed on appeal if there is evidence to support it.
Session 1.1.1
page 18
See O'Brien v. Public Service Co., 95 N.H. 79, 58 A.2d 507 (1948);
Benoit v. Perkins, 79 N.H. 11, 104 A. 254 (1918).
The jury could draw the not-so-subtle inference from the evidence before
it that the hostility of defendant's foreman *134 and connivance of the
personnel manager resulted in the letter of August 13, 1969, and that that
letter was in effect a discharge. See Colorado Civil Rights Comm'n v.
State School Dist. No. 1, 30 Colo.App. 10, 488 P.2d 83, 86 (1971). The
foreman's overtures and the capricious firing at 2:00 a.m., the seeming
manipulation of job assignments, and the apparent connivance of the
personnel manager in this course of events all support the jury's conclusion
that the dismissal was maliciously motivated."
(3) Sharpening your existing ability to identify and to make arguments that have different
logical forms
Deduction
propositional
predicate (first-order)
basic modal and deontic
Analogy
facility with argument by analogy includes the ability to move from
example to rule, and from rule to application
Inference to the best explanation
especially:
inference to the best factual explanation
inference to the best legal explanation
inference to the best logical explanation
Induction
In this course we will mention but not treat inductive arguments in detail.
Also: skill with understanding defeasible arguments.
(4) Sharpen your existing ability to use skillful reasoning to resolve rational anomalies in
legal argument, including, semantic unclarities (syntactic and semantic ambiguities,
vagueness), inconsistencies, and paradoxes (such as in State v. Jones and ProtagorasEuathlus)
EXERCISES (in addition to the exercise regarding Monge presented above)
(1)
(a) Identify one example of a rule-enthymeme in an actual legal opinion or statute or
regulation that you know of (but not from this course).
Session 1.1.1
page 19
(b) Present what you think is the best fair formal representation of that rule-enthymeme
(2)
(a) Identify one example of a (brief!) argument-enthymeme in an actual legal opinion that
you know of (but not from this course).
(b) Present what you think is the best fair formal representation of that argumententhymeme