•
Fallacies
–
A fallacy is an error in
reasoning that results in an invalid argument
–
Three common fallacies:
•
Vague or ambiguous premises
•
Begging the question
(assuming what is to be proved)
•
Jumping to conclusions
without adequate grounds
–
Converse Error:
•
Premises: p à q and q, conclusion: p
–
Inverse Error:
•
Premises: p à q and ~p, conclusion:
~q
–
It is possible for a valid
argument to have false conclusion and for an invalid argument to have a true
conclusion:
•
Premises: if John Lennon
was a rock star, then John Lennon had red hair, John Lennon was a rock star;
Conclusion: John Lennon had red hair
•
Premises: If New York is a
big city, then New York has tall buildings, New York has tall buildings;
Conclusion: New York is a big city
