What deductive reasoning can do for you!

Perhaps the greatest misfortune of philosophy is that most see it as an artistic endeavor in which an author spouts as much bullshit about the human condition as possible. Sentences which leave the mind feeling lost, perplexed, and even violated are the perceived norm. In other words, philosophy is seen as something this guy would banter on about.

Hipsterdom is a celebration of being pretentious.

The good news is that this really isn't the case. Philosophy comes in all forms, from useful to pointless, good to bad, inane to brilliant!  The good, practical, and brilliant philosophy is precisely my purpose here.

Good philosophy really isn't about anything. Well, it is about something, but that's not the point. Think of the enterprise more as a mental gym. Entering the philosophical arena provides the means for creating a strong and robust mind that can cut through any bullshit with the greatest conciseness. Good philosophy is really just the most powerful methods of thought, and it just so happens that academic Western philosophy is this applied to things such as metaphysics, politics, ethics, and the like. Creativity is required, along with skepticism and the various tools which come with it. Good philosophy is casting doubt on any argument when possible because that is how you come to truth.

The first tool in any philosopher's box is deductive reasoning. Think of this as a tool used for its cutting power. The aggregate of ideas floating in the thinkspace is daunting, but of course not all ideas are worth their weight in salt. Deductive reasoning helps slash through the bad ones almost immediately. The question is how.

Let's suppose that my friend proposes a new thought to me, but I'm skeptical. Something is wrong with her thought, but I'm not certain what. I ask for the rationale behind the thought. If I've chosen my friends well, then I'll get an argument, a set of premises with at least one conclusion, in response. Suppose it went something like this.

1. If it's raining outside, then we should go out to dance.
2. It's not raining outside.
3. Thus, we shouldn't go outside to dance.

When we speak like normal people, we usually tell our conclusion first and then give the premises as to why our conclusion is true. When we do analysis in philosophy however, it's more useful to arrange the matter like this, with the premises listed and the conclusion last (with a word to demarcate it, too.) Now, hopefully my friend's argument has struck as a bit queer. Certainly the fact that it isn't raining doesn't necessarily mean that we shouldn't dance. Right? People in Tucson, Arizona would quite dull lives if that were the case. Actually, that's generally true (partially why I'm writing this blog.) The major point here is that there are other reasons we should go outside to dance. Also, the key word here is 'necessarily.' Deductive reasoning is all about things which we can't conceive the negation of, as Hume put it. In this case we definitely can conceive of the negation. Or, in other words, if the premises are true, then they do not guarantee the truth of the conclusion. This is the notion of validity and is one of the most important concepts you can learn, this is the concept with a lot of cutting power.

A valid argument is one with premises which guarantee the truth of its conclusion, if the premises are true themselves. An invalid argument is one with premises that fail to give this type of support. Emphasis on "if the premises are true." When checking for validity, we don't really care if the premises are actually true, that comes later. Instead, we can just pretend that they are true. In fact, we don't even really need to know what the premises say specifically. We can replace the details with symbols. My friend's argument can be represented like this.

1. If P, then Q
2. It is not the case that P
3. Thus, it is not the case that Q

With P standing in place for 'it is raining outside' and Q for 'we should go out to dance.' And there you have it, the generalized form of my friend's argument. The same problem with the specific argument my friend gave applies here as well. Just because P isn't the case doesn't mean that the same has to be true of Q There could be other things that yield Q! Thus, this argument is invalid because the premises don't guarantee the truth of the conclusion. Now, of course not every idea in the thinkspace is going to be supported by arguments of this form. There are plenty others, some valid and some not. Here's a few valid forms, you would do well to become familiar with them.

1. If P, then Q.
2. P.
3. Thus, Q.

1. If P, then Q.
2. Not Q.
3. Thus, not P.

1. Either P or Q.
2. Not P
3. Thus, Q.

1. If P, then Q.
2. If Q, then R.
3. Thus, if P, then R.

And a couple invalid forms.

1. If P, then Q.
2. Q.
3. Thus, P.

1. Either P or Q.
2. Q.
3. Thus, not P.

So there you go. That's a bit about validity. It doesn't exactly get the blood flowing, but it's an important tool in crushing other ideas. If an argument turns out to be invalid, then not much else can be said. It's inferring too much and is just a bad argument. There is plenty more to be said about deductive reasoning, but this is a good start. Now, whenever you hear a politician speak, be sure to catch their conclusion and premises. See if you can formulate their argument as we did here. Check for validity. And above all else, remember that a day without valid arguments is like a day without sunshine - dark, hopeless, bleak, and probably attracts hipsters.