Argumentation 1/7: What's The Point?
Imagine for a moment that you and a friend are at the movie theater to watch a new film. Excitedly you both purchase tickets and the attendant tells you the film you're going to see is down the hall to the left, in which there are two doors. You open the door to the first theater and ask someone inside which film this is for. It's the wrong one. You go into the second door this time without asking anyone if you're in the right place. Without thinking about it you've used logic.
We use argumentation everyday often without ever realizing. In deductionism we use a branch of formal logic called sentential logic (sometimes called prepositional logic). That means we take large blocks of text and convert them into sentences which we can then prove to be true or false. The argumentation this blog will be covering is the most basic form of sentential logic. If you've ever taken a Logic 101 course, you probably already know what I'm going to talk about over this series of posts. That being said, it would be smart to follow along and practice even if you have a grasp of the subject because it flows directly into the following series.
"Why!" I hear you yell. "Why should I learn argumentation and add unnecessary symbols and complexity to my deductions when I already use logic in my day to day life?" You need a strong foundation in logic otherwise the only thing you’ll be inferring is television plots. I’m serious, I don't care how good you think you are, professionals who use deductionism understand logic and use it as the basis of their work. Deductionist Ben Cardall uses logic as one of a few tools he shifts between during his work. In fiction, writers shield us from the unappealing work involved in problem solving, but believe me when I say your favorite detectives use formal logic (unless your investigator of choice is Mr. Magoo).
Deduction IS logic. If someone tries to convince you otherwise they’re being very silly. When Sherlock Holmes deduces the occupation of someone from a callus on their thumb or where they were three hours ago from the dampness of their umbrella, that's not just memorization and intuition (though those skills would certainly be at play). Holmes makes many, many logical proofs in his head quickly. This skill is the thing that I believe divides deductionists with room to grow from those who will stay at their respective skill plateau forever. This series is only one fifth of the beginner stage, but the abilities gained from it are worth half. This is the most important thing to get right.
Let’s take the example from the beginning of the post and break it down:
Film A is behind Door 1 or Door 2.
Film A is not behind Door 1.
Therefore, Film A is behind Door 2.
If each of our premises are true, then the conclusion MUST be true. Does that sound familiar? “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” Oh right that’s Sherlock Holmes describing his “enlightened common sense”.
We have a lot to cover and in the next few weeks we'll be going into detail on how to take similar examples to the next level. We'll begin with logical operations and convert large chunks of text into simple sentences, then build on those premises with truth tables, reconstruct those simple sentences with replacement rules, develop new premises with rules of inferences, and finally solidify everything with proofs. I would suggest going through this series multiple times and practicing each of the parts. If you learn to do these things automatically you will make deductions from information you didn't know you had access to.
-CM
