Arguments and Ambiguity Flashcards
What is an argument?
A set of premises and a conclusion where the premises are intended to support the conclusion
What is rhetoric?
Any device used to convince us of something without reason, e.g. emotion, appeal to values etc
What is the difference between lexical and syntactic ambiguity?
Lexical ambiguity is introduced by an ambiguous word
Syntactic ambiguity is introduced by the structure of the language
What is Syntactic ambiguity?
When the structure of the language makes the sentence ambiguous
e.g. Cocaine users are getting younger> are younger people using cocaine or is cocaine making people younger?
What is lexical ambiguity?
When an ambiguous word is used, it may have multiple different meanings
What is an indexical?
Words that are dependent on context and would be ambiguous without it
e.g. here, you, me, I
I am thirsty> well whose thirsty then?
What is a demonstrative?
Words that demonstrate and introduce the noun in the sentence, e.g. these, those, that
That is red> what is red?
What is a proposition?
A declarative sentence, it makes a statement not a command or question
e.g. The BMW car is red
What is a valid argument?
Where the conclusion logically follows on from the premises.
An argument is only valid iff its form is such that whenever the premises are true the conclusion is true
What’s the difference between validity and truth?
An argument may be valid without containing any true propositions whereas propositions can be true or false
e.g.
All mammals are dogs
Pegasus is a mammal
__________________________
Pegasus is a dog
What is a sound argument?
An argument is sound iff it is valid and its premises are true
What steps must you take to reconstruct an argument?
-Only use unambiguous, declarative sentences
-Remove rhetoric
-Remove grammatical ambiguity
-Remove lexical and grammatical ambiguity
-Work out the logical form of the argument
What are some examples of a valid but unsound argument?
P1 If Boris is a vegetarian, then
Boris is a redhead
P2 Boris is vegetarian
___________________________________
C Boris is a redhead
Modus Ponens
P1 Daphne is a cat and Daphne is
red
___________________________________
C Daphne is red
‘And’ elimination
P1 It is not the case that Sojourner Truth is not a vicar
___________________________________
C Sojourner Truth is a vicar
Double negation
ALL TRUTH-PRESERVING FORMS OF ARGUMENT
What does truth-preserving argument mean?
It means that if you inserted true premises, true conclusions would come out
What are some examples of some sound and valid arguments?
P1 If Boris is a tory, then Boris is a
conservative
P2 Boris is a tory
___________________________________
C Boris is a conservative
Modus Ponens
P1 Daphne is a spaniel and
Daphne is black
___________________________________
C Daphne is black
‘And’ elimination
P1 It is not the case that
Sojourner Truth is not a
woman
___________________________________
C Sojourner Truth is a woman
Double negation
These are truth-preserving but with true premises and true conclusions
