You just finished the pretest that I give to my logic class on their first day.Some basic definitionsMost people who haven't studied logic get about half the problems wrong. Untrained logical intuitions tend to be unreliable. A logic course can sharpen your logical intuitions and teach you various ways to test whether reasoning is valid.
I designed this pretest for a friend in psychology who wanted to test sex-differences in reasoning. Despite the common belief that females are less logical than males, my friend found that both groups did equally well.
Logic is the analysis and appraisal of arguments. An argument is a set of statements consisting of premises (the data) and a conclusion (that which is inferred from the data). Here's a simple example:Validity and truthAll humans are mortal. VALID
This argument is VALID. This means that the conclusion follows from the premises. Equivalently, it would be impossible for the premises to be true while the conclusion was false. The opposite of "valid" is "invalid." Calling an argument "valid" doesn't say whether its premises are true.
Socrates is human.
So Socrates is mortal.
When we try to prove something, we try to give a SOUND argument -- one that is valid (the conclusion follows from the premises) and has true premises. The conclusion of a sound argument will always be true.When we attack an argument, we usually try to show that it's UNSOUND. We try to show that the conclusion doesn't follow from the premises or that one or more of the premises are false. Showing that the argument is unsound doesn't refute the conclusion. The conclusion might still be true -- and our opponent might later find a better argument for it.
<= back | menu | forward =>