Definitions and Examples of Enthymemes

1. In everyday language, nearly all syllogistic-type arguments are expressed as enthymemes. Usually, the missing proposition in such an argument is taken for granted for ease of expression and is evident to the reader.
   
   Often, if the missing statement were to be explicitly stated, the argument would lose rhetorical effectiveness and might be thought of as “stating the obvious.”
   
   
   
2. Varieties of logical enthymemes are classified in order of their frequency of occurrence. Note that an enthymeme conveys just a single inference.
   
   
   

   1. A first order enthymeme omits the major premise:

      E.g., “Balbus is avaricious, and therefore, he is unhappy.”

      [ . . . . . . . . . . . . . . . . ]

      Balbus is an avaricious person.

      ∴ Balbus is an unhappy person.

      Implicit Major Premise: “All avaricious persons are unhappy persons.”
      
      
      

   2. A second order omits the minor premise:

      E.g., “All avaricious persons are unhappy, and therefore, Balbus is unhappy.”

      All avaricious persons are unhappy persons.

      [ . . . . . . . . . . . . . . . ]

      ∴ Balbus is an unhappy person.

      Implicit Minor Premise: Balbus is an avaricious person.
      
      
      

   3. A third-order omits the conclusion:

      E.g., “All avaricious persons are unhappy, and Balbus is avaricious.”

      All avaricious persons are unhappy persons.

      Balbus is an avaricious person.

      ∴ [ . . . . . . . . . . . . . . . ]

      Implicit Conclusion: Balbus is an unhappy person.
      
      
      
   4. Rhetorical enthymemes are classified in the same manner. Seventeenth century classical scholar Henry Aldrich explains this type of syllogism (when the missing statement is completed) with the following example:

      Most men who envy hate.

      This man envies.

      ∴ This man (probably) hates.

      The major premise is an “almost” universal statement; the minor premise is viewed as a singular sign
      close ×

      sign:

      For Aristotle, enthymematic signs are statements which can be “necessary” as a universal premise's relation to its particular conclusion, or “not necessary” as a particular premise's relation to its conclusion as a probable general observation or empirical generality. APr 2.27 and Rh 1.2.16.1357b. See footnote 1 below.
      of the conclusion. This syllogism is not intended to be deductive, for the major premise lacks universality, and the middle term is undistributed in both premises.[2]

Stylistic reasons for the use of enthymematic arguments.

1. In some cases, the missing proposition is not explicitly stated because the inference is only probable. In cases such as these, if the missing premise or conclusion were to be explicitly supplied, the argument would test out as formally invalid or unsound.[3] Fairly often enthymematic arguments seem sound but are invalid or they are based on suppressed statements which are false or questionable.
   
   
   
   1. The following enthymematic example is often (mistakenly) attributed to Alexis de Tocqueville: [4]
      
      
      “America is great because she is good.”
      
      Implicitly, the conclusion “America is great” logically follows only if the doubtful assumed premise ”All good nations are great nations” is added to the given premise “She (i.e. America) is good.
      
      Thus, when the argument is explicitly reconstructed into standard form and order, it becomes …
      
      
      [All good nations are great nations.]
      

      America is a good nation.

      ∴ America is a great nation.

      
      Note that in constructing the argument as valid, we were necessarily restricted to a false major premise. (I.e., the premise is false because some good nations are not great.) Consequently, the argument is unsound.[5]
      
      
      
   2. Consider this second example:
      
      
      “You'll do fine, just follow your heart.”
      
      The implicit premise necessary for validity in this argument would be “All persons who follow their heart are persons who do fine.”
      
      
      [All persons who follow their heart are persons who do fine.]
      

      You are a person who follows your heart.

      ∴ You are a person who does fine.

      
      Note that the explicit statement of the missing premise makes the argument valid but unsound since the supplied premise is clearly false. (Some persons who follow their heart do not do well.)
      
      
      
   3. In the third example, the following enthymeme, authored by Friedrich Nietzsche, leaves its conclusion unstated. If the argument were meant to be deductive and if it were explicitly stated, the reader might recognize that the argument is invalid.
      
      Nevertheless, it may well be that in an everyday context, the argument was never meant to be deductive; instead, it might have been intended to be an inductive, rhetorical enthymeme:
      
      
      “There is always some madness in love. But there is always, also some method in madness.”[6]
      
      The conclusion intuitively suggests itself as …

      “Therefore, there is some method in love.”

      So, the argument can be set up as something like …
      
      
      Some aspects of madness ^U are qualities of love.
      

      Some methods are aspects of madness.^U.

      [Some methods are qualities of love.]

      
      As a deductive argument, the fallacy of the undistributed middle term occurs. However, as part of everyday language, the argument is best rhetorically interpreted as intended to be persuasive or probable.
      
      
      
2. In other cases, if the missing proposition were explicitly present, the argument might lose rhetorical force. E.g. …
   
   
   “Mary does well because she pays attention.”
   
   Here, the suppressed premise necessary for validity would be “All attentive people are people who do well.” And so, the argument when stated explicitly becomes:
   
   
   [All attentive people are people who do well.]
   

   Mary is an attentive person.

   ∴ Mary is a person who does well.
   

   
   Since it seems reasonable to assume that not all attentive people do well, this reconstruction is an unsound argument.
   
   However, if we adopt the principle of charity, the argument should be viewed as inductive or probable (rather than deductive and invalid) with the implicit major premise being:

   “Many attentive people are people who do well.” rather than “All attentive people are people who do well. ”

   Even though the argument is logically unsound, it is rhetorically influential.
   
   
   
3. Occasionally, a proposition is suppressed to conceal the unsoundness or the invalidity of the argument. E.g., in Shakespeare's The Merchant of Venice when the rich heiress Portia is asked how she likes one of her suitors who is a hard drinking young German, she responds:

   “Very vilely in the morning, when he is sober; and most vilely in the afternoon, when he is drunk … I will do anything … ere I'll be married to a sponge.[7]

   Since Shakespeare is using the metaphor “sponge” for someone who almost always drinks too much, the implicit enthymeme is as follows:

   [A sponge is someone who almost always drinks too much.]
   

   The young German is a person who almost always drinks too much.

   ∴ The young German is a sponge.

   This analysis assumes that some persons who occasionally drink too much are not sponges. Although the logic might appear good in the quotation, under examination, the fallacy of the undistributed middle terms is found.
   
   In sum, as logician and economist John Neville Keynes points out:

   “[F]allacious arguments … are seldom completely stated, or their want of cogency would be more quickly recognised.[8]

   Keynes' observation applies to both logical and rhetorical enthymematic arguments.
   
   
   
4. Note: Most sources define an enthymeme as an argument in which a premise is missing; nevertheless, some enthymemes, such as the following, omit the conclusion in order to tweak a rhetorical effect:
   
   
   “Self-absorbed people don't help charities and I know you're not self-absorbed.”
   
   In this psychologically manipulative reasoning, the import of the missing conclusion would be intended to be something like:

   “So I'm sure you will help” (with a formal conclusion being stated as “You are a person who helps charities.”)

   However, no conclusion validly follows from two negative premises.
   
   Possibly in this case, the conclusion was left unstated both to cover up the fact that the argument is invalid and for the supposed rhetorically persuasive effect of appealing to one's vanity in order to obtain help for a purported charity.
   
   Reconstructing the full argument, we obtain the following syllogism:
   
   
   No self-absorbed people are persons who help charities.
   

   You are not a self-absorbed person.

   (Note: this statement is treated as an E-form statement.)

   ∴ [You are a person who helps charities.]

   (Note: this statement is considered an A-form statement.)
   
   As mentioned above, this syllogism tests out invalid because of its exclusive premises. The argument also is fallacious because no valid syllogism can have an affirmative conclusion from a negative premise.
   
   
   

How to Evaluate an Enthymeme

(1) the rules and the fallacies of standard form categorical syllogisms, and …

(2) techniques to translate ordinary language into standard form categorical statements, and …

(3) knowledge of the distribution statuses of those statements.

1. By the principle of charity, we should attempt to supply a missing statement completing the argument as valid if possible — unless the context of the passage explicitly prevents such an interpretation.
   
   
   
   1. To be able to supply the missing statement requires through knowledge of the fallacies and rules for syllogisms and an understanding of the context in which the argument occurs and the purpose to which the argument is applied.
      
      
   2. Reconstructing Formal (Deductive) Enthymemes: Initially, it might be necessary to check off each syllogistic rule systematically in order to deduce the appropriate missing statement. Later, once the rules and fallacies become familiar, systematic checking will seldom be necessary for disclosing the intended missing proposition in formal arguments.
      
      
   3. Reconstructing Informal (Rhetorical) Enthymemes: When translating an enthymeme into a standard form syllogism, be careful not to supply a proposition which makes the argument invalid when such a proposition was not intended in the original context of the argument; otherwise, the straw man fallacy could occur.
      
      E.g. Examine this complaint by Arthur Schopenhauer about the quality of literature in his day:

      “The reason why literature is in such a bad plight nowadays is simply and solely that people write books to make money.”[9]

      It would be an error to interpret Schopenhauer as asserting that every writer at that time wrote literature to make money or even to interpret him to be implicitly assuming that all money-seeking-authors are creators of poor literature.
      
      Instead, a possible reconstruction of Schopenhauer's argument could be something like the following argument:
      
      
      Most avaricious writers create poor literature.
      Most current writers are avaricious.
      Most current writers create poor literature.
      
      
      Again, in general, discovery of an appropriate implicit statement to complete an enthymeme should be in line with the principle of charity.
      
      
   4. Logician Michael Scriven has some helpful advice:

      “[P]roduce a set of premises which together convey the essential content of the assumptions underlying the argument. … First, the assumptions have to be strong enough to make the argument sound. Second, they should be no stronger than they have to be, since they might then be too strong to be true, and you would then have constructed a ‘straw-man’ version of the argument … Third … try to relate the assumptions as you formulate them to what the arguer would be likely to know or would believe to be true.[10]

      A straw man fallacy occurs whenever a proponent's argument is misrepresented by an opponent and then rejected as if the misrepresentation were the original argument at issue.
      
      
2. First, let us consider some example enthymematic arguments based on statement forms alone. To see if these elliptical argument forms are “valid forms” we must supply the suppressed proposition in accordance with the rules for validity.
   
   
   
   1. Example 1:
      
      
      Some M is not P
      

      All M^D is S^U

      ∴ [. . . . . . . . . . .]

      
      We can systematically check each syllogistic fallacy and its corresponding rule to determine the structure of the statement form necessary for validity.[11]
      
      
      
      1. Four Term Fallacy: The syllogism must have exactly three terms.
         
         The argument form already has exactly three terms corresponding to S, P, and M. Since we are dealing with syllogistic forms and not actual statements this rule is inapplicable.
         
         
      2. Fallacy of the Undistributed Middle Term: The middle term must be distributed at least once in the premises.
         
         The middle term is distributed in the subject of the minor premise (as the subject of an A proposition), so this rule was not violated.
         
         
      3. Fallacies of Illicit Minor or Major Terms: If a term is undistributed in a premise, it cannot be distributed in the conclusion.
         
         (Otherwise, we would be reasoning from only part of a class to a conclusion involving the entire class.) Since the minor term S is undistributed in its premise, the minor term S cannot be distributed in the conclusion or else the fallacy of illicit minor would occur.
         
         
      4. Fallacy of Exclusive Premises: At least one premise must be affirmative.
         
         This rule checks out OK since the minor premise is affirmative.
         
         
      5. Fallacy of an Affirmative Conclusion from a Negative Premise: If a premise is negative, the conclusion must also be negative.
         
         Since the major premise of the argument is negative, the missing conclusion must be negative or else the fallacy of Affirmative Conclusion for a Negative Premise would occur.
         
         
      6. Existential Fallacy: If both premises are universal the conclusion must be universal as well.
         
         Since the major premise of the argument form is particular, this rule does not apply.
         
         
         
      Thus, from our examination of the syllogistic rules, we conclude that the conclusion must meet the following requirements:

      * The conclusion must contain both the S and P terms (by terminological definition).

      * The conclusion must be negative with the minor term S undistributed.

      Hence, the conclusion must be the O statement:

      “Some S^U is not P^D”

      
      
   2. Example 2:
      
      
      [. . . . . . . . . . .]
      

      Some S is M^U

      ∴ Some S is not P^D

      
      
      1. From our knowledge of the positions of terms in syllogistic forms, we know the missing major premise contains P, the major term, and M, the middle term (but we do not know, of course, their subject and predicate position yet.
         
         
      2. Since the middle term is undistributed in the minor premise, M must be distributed in the major premise or else the fallacy of the undistributed middle term would occur.
         
         
      3. Since the major term P is distributed in the conclusion, P must be distributed in the major premise or else the fallacy of the illicit process of the major term would occur.
         
         
      4. Thus, the missing major premise must have both terms distributed. So the major premise is an E statement:

         Either “No M is P” or
         “No P is M” fits the bill.

Enthymeme Practice Exercises with Answers

1. All M is P
   

   [. . . . . . . . . ]

   ∴ All S is P

   Answer
   Answer: The missing premise must be affirmative or else the fallacy of an affirmative conclusion from a negative premise would occur. It must also distribute the minor term S since the minor term is distributed in the conclusion or else the fallacy of illicit minor would occur. So the missing premise is:

   All S is M

   
   
   
2. No P is M.
   

   [. . . . . . . . .]

   ∴ No S is P.
   
   Answer

   The missing premise must be affirmative or else the fallacy of exclusive premises would occur, and the minor term must be distributed or else the fallacy of illicit minor would occur. Hence, the missing premise has to be:

   All S is M

   
   
   
3. And finally a more difficult syllogistic form:
   
   [. . . . . . . . . . . . . .]
   

   Some M is not S

   ∴ Some S is not P

   
   Answer
   To avoid the fallacy to two negative premises, the major premise must be affirmative.
   
   But the major term must be distributed since it is distributed in the conclusion (otherwise fallacy of illicit major would occur), and the middle term must also be distributed since it is undistributed in the minor premise (or the fallacy of the undistributed middle would occur).
   
   No affirmative statement has both terms distributed, so there is no solution of constructing this problem into a valid syllogistic form.
   
   Consequently, no supplied major premise would test valid in this syllogistic form.
   
   
   
   
   
4. As a fairly difficult ordinary language problem, try to reconstruct this argument from State Mutual of America, an insurance company offering reduced rates of life insurance for nonsmokers:
   

   “You see we're convinced that people who don't smoke cigarettes are better risks than people who do, and better risks deserve better rates.”

   Set up the enthymeme and find the missing concluding statement:
   
   

   Answer
   All better risks are deservers of better rates.^U
   

   All nonsmokers are better risks.

   ∴ [ . . . . . . . . . . . . . . . . . . . . . . . . . ]

   The missing conclusion must be universal to avoid the existential fallacy and must not distribute the major term in the conclusion in order to avoid the fallacy of the illicit minor term.
   
   Hence, the missing conclusion is an A type:

   All nonsmokers are deservers of better rates.^U