If philosophy interests you, do get this book – I absolutely adore it. Here are some excerpts from the book:
Deductive logic reasons from the general to the particular. The bare-bones deductive argument is the syllogism “All men are mortal; Socrates is a man, therefore Socrates is mortal.” It’s amazing how often people screw this up and argue something like “All men are mortal; Socrates is mortal; therefore Socrates is a man,” which doesn’t logically follow. That would be like saying, “All men are mortal; my kid’s hamster is mortal; therefore my kid’s hamster is a man.” Another way to screw up a deductive argument is by arguing from a false premise.
An old cowboy goes into a bar and orders a drink. As he sits there sipping his whiskey, a young lady sits down next to him. She turns to the cowboy and asks him, “Are you a real cowboy?”
He replies, “Well, I’ve spent my whole life on the ranch, herding horses, mending fences, and branding cattle, so I guess I am.”
She says, “I’m a lesbian. I spend my whole day thinking about women. As soon as I get up in the morning, I think about women. When I shower or watch TV, everything seems to make me think of women.”
A little while later, a couple sits down next to the old cowboy and asks him, “Are you a real cowboy?”
He replies, “I always thought I was, but I just found out I’m a lesbian.”
Perhaps it would be fun to analyze where exactly the cowboy went wrong. Perhaps not. But we’re going to do it anyhow. In his first answer to the question of whether he is a real cowboy, he reasoned,
1. If someone spends all his time doing cowboy-type things, then he is a real cowboy.
2. I spend all my time doing cowboy-like things.
3. Therefore, I am a real cowboy.
The woman reasoned,
1. If a woman spends all her time thinking about other women, then she is a lesbian.
2. I am a woman.
3. I spend all my time thinking about women.
4. Therefore, I am a lesbian.
When the cowboy then reasons to the same conclusion, he assumes a premise that in his case is false: namely (2) I am a woman.
The authors also discuss why arguments from analogies often produce unsatisfying outcomes. In the process, they mention a contest run by The Washington Post, titled “Worst Analogies Ever Written in a High School Essay”.
1. “Long separated by cruel fate, the star-crossed lovers raced across the field toward each other like two freight trains, one having left Cleveland at 6:36 pm travelling at 55 m.p.h, the other having left Topeka at 7:47 travelling at 35 m.p.h.”
2. “John and Mary had never met. They were like two hummingbirds who had also never met.”
3. “The little boat gently drifted across the pond the way a bowling ball wouldn’t.”