Logical Arguments


















Does the conclusion follow from the premises?

	premises:	1. If it snows, I'll go skiing.
			2. It's snowing.

	conclusion:	3. I'll go skiing.
















Does the conclusion follow from the premises?

	premises:	1. If it snows, I'll go skiing.
			2. It's not snowing.

	conclusion:	3. I won't go skiing.
















What's a Valid (or Sound) Argument?

Do the premises have to be true for an argument to be valid?


An Important Valid Argument

Modus Ponens

	premises:	1. If P, then Q.
			2. P.
	conclusion:	3. Q.


















Predicates in Arguments

premises:	if 'Bob' thinks then 'Bob' exists
		'Bob' thinks
conclusion:	'Bob' exists

premises:	if thinks('Bob') then exists('Bob')
		thinks('Bob')
conclusion:	exists('Bob')

premises:	if thinks(X) then exists(X)
		thinks(X)
conclusion:	exists(X)

premises:	thinks(X) -> exists(X)
		thinks(X)
conclusion:	exists(X)

premises:	exists(X) :- thinks(X)
		thinks(X)
conclusion:	exists(X)


















How does this apply to the projects?

Facts:
	thinks('Tracy').
	exists('Lynn').
Rules:
	exists(X) :- thinks(X).
Queries:
	exists('Lynn')?
	exists('Tracy')?
	exists('Kelly')?