This is the second post in my series on critical thinking; you can read my first post on why it’s important here.
Argument — a series of premises used to support a conclusion. Here is an example: all human should have the same rights; women are human beings; therefore, women should have the same rights. An argument is considered valid if the the premises support the conclusion; that is, there is no way the conclusion can be true if the premises are false, or vice versa. The above statement is a valid argument: to argue against women’s rights, you either have to deny all people should have the same rights or deny that women are people! But since the premises are, in fact true, and they support the conclusion, making it true, the argument is called a sound argument, having both true premises and a true conclusion. A sound argument is always valid, but not every valid argument is sound. Here’s an example of an argument that is not valid: all New Yorkers are Americans; Californians are Americans; therefore, Californians are New Yorkers. The problem with this is that both New Yorkers and Californians are subsets in the group known as “Americans” and thus are not the same.
Now I’m going to talk about the two types of reasoning: deductive reasoning and inductive reasoning. Deductive reasoning seeks to show conclusion that are true, provided the premises are true. The previous paragraph used deductive reasoning. By contrast, inductive reasoning draws conclusions based on observations. Here’s an example: over the past two years the blogger has posted every Wednesday; therefore, there will be another post this Wednesday. For inductive reasoning, as opposed to deductive reasoning, only shows conclusions to be likely. In my example, there’s a possibility that the blogger won’t post on Wednesday.
I’ll conclude with the Wason Selection Task: I have a deck of cards that have a number on one side and a color on the other side. I deal out four cards: 3, 8, red, Brown, and say, “If a card has an even number, the opposite side must be red. Which card(s) must you flip over to prove whether or not I’m lying?”
3, 8, red, brown — which one(s) do you flip? I’ll give the answer in the next post in this series; please feel free answer in the comments.