Whether you need to polish your skills for your Philosophy 100 class, or you just want to make a better case for some position that you believe strongly in, you'll benefit from a quick lesson in how to argue persuasively.

Now, when we use the term "argument" here, we're not just talking about a disagreement or a fight. There is a more specific usage of the term, common to philosophy, law, and other academic fields. Essentially, an argument is a series of propositions intended to establish some conclusion or conclusions.

For instance, consider this possible argument: "All kittens are cute, all cute things can speak Latin, therefore all kittens can speak Latin." This sounds pretty wacky, and indeed it is - who would actually believe that conclusion? But let's look at this argument (and others) a bit closer to see what makes a good one.

In the kitten argument above, we admitted that the conclusion is ridiculous... of course it's false that all kittens can speak Latin. In fact, I doubt any kittens can do that. So, clearly there is something wrong with our facts somewhere.

But look closely at the argument's structure, or form... what do you notice? Here's what the skeleton of the argument looks like: "All X is Y, all Y is Z, so all X is Z." When we take out the particulars, and just look at the kind of reasoning that's going on behind them, it should be clear that the argument's form is actually a good one. If our premises - i.e. our supporting sentences - are true, then the conclusion must be true too. This called "validity."

Think about it: if every X is a Y, and every Y is a Z, then it has to be true that every X is also a Z... by virtue of their being Y. So, validity concerns itself with the form of an argument... if its premises are true (Big If!), then its conclusion must also be true thanks to the structure of the argument. This structure preserves any truth that occurs in the premises, and carries it into the conclusion.

When looking at your actual argument, check its form. There are many valid argument forms available on the Internet. Please reference the footnote if you want to look at a page for some valid forms. http://editthis.info/wiki/Valid_and_Invalid_Logical_Forms#Valid_Forms

Now, go back to the kitty argument. We've seen that it is a valid argument, because of its form or structure. We also defined validity as a kind of "if...then" idea.

Our kitty argument is overall a 'bad" argument because the facts are wrong. You might think it's true that all kittens are cute. But certainly it's false that all cute things can speak Latin. If these statements were true, then the conclusion would be true, too. It would have to be, since that's how validity works.

A valid argument which has true premises is called a "sound" argument. This is the best kind to have, since it contains both good structure and true premises. And thus, it *must* have a true conclusion.

The arguments we've been looking at are examples of "deductive" arguments, since you can deduce or infer the conclusion from just what is contained in the premises. http://en.wikipedia.org/wiki/Deductive_reasoning

You may often look at some argument or other and notice that it seems "fishy". Either somebody is making too big of a jump in their conclusion, or else they're just attacking someone's character in order to disprove his/her position. This is, as you should know, frowned upon. It is one of the easiest ways to "strike out" when arguing. These errors are called "fallacies."

There is a site dedicated to all of the logical fallacies. Please reference it with this footnote: http://www.logicalfallacies.info/

Let this be your "never never never" list; never, never, never fall into any of these traps!

If you are trying to disprove someone's argument, then you need to attack their facts or else the form of their argument.

There is another class of arguments, called "inductive" arguments. Inductive arguments, in the words of logician P.D. Magnus, "generalize from many cases to a conclusion about all cases." http://www.fecundity.com/codex/forallx.pdf

Magnus, on p. 9 of his book forallX, gives the following example of an inductive argument:

"In January 1997, it rained in San Diego. In January 1998, it rained in San Diego. In January 1999, it rained in San Diego. Therefore, it rains every January in San Diego." http://www.fecundity.com/codex/forallx.pdf

Now, inductive arguments cannot be valid or invalid; their premises can be true or false, and thus give you more or less reason to believe the prediction or generalization. But there is no perfect structure to be found here. Inductive arguments are useful, though they are open to criticism on the ground that they don't really offer certainty like deductive arguments (i.e. the kind we discussed earlier). http://en.wikipedia.org/wiki/Inductive_reasoning