h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hi,

Great article, very interesting, but I just thought one thing needs correcting:

I think that in proper terminology the examples of deductive arguments that you gave are in fact *valid*, but they are not *sound*.

Valid arguments are true if their premises are true

Sound arguments are valid ones with true premises.

In other words, validity refers only to the argument form, whereas soundness refers to the truth or falsehood of the premises themselves.

For instance, the following arguments are all valid:

P1 All politicians are aliens
P2 Tony Blair is a politician
=> Tony Blair is an alien


P1 All americans live in Europe
P2 My Cousin is an American
=> My Cousin lives in Europe

P1 All Philosophy students have to write essays
P2 I am a philosophy student
=> I have to write essays

But only the third is technically *sound*..

Cheers

Will

Thank you very much. That was an oversight. Possibly there should be a footnote distinguishing between the two.