Home > Jon Boldt, Lectures, Seth Kurtenbach > Fallacies of Ambiguity – Lecture Notes

Fallacies of Ambiguity – Lecture Notes

Ambiguity:  Occurs when a word or expression     is misleading or potentially misleading because it’s hard to tell which of a number of possible meanings is intended in the context. (pg. 333)

 

Ambiguity vs. Vagueness

Vagueness:
There are a range of boarder line cases where it isn’t clear if a concept applies.   There’s no clear place where the line should be drawn.

Ambiguity:  
An expression has more than one distinct meaning and it isn’t clear, given the context, which meaning applies.
Context can clarify ambiguity.  For example, consider the ambiguous claim, “Give me five!”

In the context immediately following a great and powerful achievement, this may mean “Give me a high five for the purpose of celebration!”  (That’s how cyborgs always say it.  Very unambiguous, cyborgs.)

 

However, in the context of a deli, in which the guy behind the counter says, “You want any slices of Swiss cheese?”, it may mean, “Good sir, please give me five pieces of Swiss cheese, and no fewer!”

 

 

Fallacy of Equivocation

Occurs when an argument uses the same expression in different senses in different places, and the argument is ruined as a result. (pg. 337)

(1) Six is an odd number of legs for a horse.
(2) Odd numbers cannot be divided by two.
(3) Therefore, Six cannot be divided by two.

Odd”: “Unusual” versus “not even”

Using the same meaning of the word in all premises… 

(1) Six is an unusual number of legs for a horse.
(2) Unusual numbers cannot be divided by two.
(3) Therefore, Six cannot be divided by two.

UNSOUND:  Premise (2) false

(1) Six is an uneven number of legs for a horse.
(2) Uneven numbers cannot be divided by two.
(3) Therefore, Six cannot be divided by two.

UNSOUND:  Premise (1) false

Using the intended meaning of the word in each premise…

(1) Six is an unusual number of legs for a horse.
(2) Uneven numbers cannot be divided by two.
(3) Therefore, Six cannot be divided by two.

INVALID:  Conclusion does not follow necessarily from premises.

Example from real life philosophy:

John Stuart Mill (1806 – 1873)

(1)  If something is desired, then it is desirable.
(2)  If something is desirable, then it is good.
(3)  If something is desired, then it is good.

“Desirable”:
“capable of being” desired versus “worthy of being desired”

- Using the same meaning of the expression in each premise…

(1) If something is desired, then it is capable of being desired.

(2) If something is capable of being desired, then it is good.

(3) Therefore, If something is desired, then it is good.

UNSOUND: Premise 2 is false.

(1) If something is desired, then it is worthy of being desired.

(2) If something is worthy of being desired, then it is good.

(3) Therefore, If something is desired, then it is good.

UNSOUND: Premise 1 is false.

 

- Using the intended meaning in each premise…

(1) If something is desired, then it is capable of being desired.

(2) If something is worthy of being desired, then it is good.

(3) Therefore, If something is desired, then it is good.

INVALID: Conclusion does not follow from the premises.

So, no matter what, an argument that equivocates is unsound:  it is either valid with a false premise, or invalid!

What to do if you suspect an argument commits the fallacy of EQUIVOCATION:

1.  Distinguish possible meanings.

2. Restate the argument using each possible meaning, in various combinations.

3.  Evaluate each restated argument and ask if the premises are false or if the argument is now invalid.

 

Definitions

1. Lexical Definitions:  Dictionary type definitions.  For example,

bank, n 1. a long pile or heap; mass.
2. an institution for receiving, lending, and safeguarding money and transacting other financial business.

2. Disambiguating Definitions:  Tell us which dictionary definition is intended in a particular context (semantic disambiguation).  Example,

      “. . . By ‘bank’ I mean a place where you would deposit money, not a river bank.”

Or,   or remove syntactic ambiguity…

     “When I say “All of my friends are not students” I mean not all of my friends are students.  I’m not saying that none of my friends are students.”

3. Stipulative Definitions: assign meaning to a new term or a new meaning to a familiar term.  For example,

“. . . By ‘hangry‘ I mean ‘happy and angry at the same time.”

4. Precising Definitions: used to resolve vagueness.  For example,

Specifying the maximum annual income one can have while
still being considered “poor”, for the purposes of
government reporting.

5.  Systematic/Theoretical Definitions:  introduced to give systematic order to a subject matter.  For example,

Using primitive notions to define define more complex
secondary notions (as in science and mathematics).

 

 

 

 

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