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| 1 | All griznoxes chorble happily. | Premise |
| 2 | A floober is a type of griznox. | Premise |
| 3 | Therefore, floobers chorble happily. | Syllogism, lines 1,2 |
You don't need to be a world-class floober expert to evaluate this argument, either.
As you've noticed, the form of the argument is the same in all these.If you are assured that the first two premises are true, then, without any true understanding,you (or a computer) can automatically come up with the conclusion. A syllogism is one example of a inference rule that is, a rule form that a computer can use to deduce new facts from known ones.
Of course, not all arguments are valid proofs. Identifying invalid proofs is just as interesting as identifying valid ones.
Homer: Ah, not a bear in sight. The Bear Patrol must be working.
Lisa: That's
specious reasoning, Dad.
Homer: Thank you, honey.Lisa: By your logic, this rock keeps tigers away.
Homer: Oh? How does it work?Lisa: It doesn't work.
Homer: Uh-huh.Lisa: It's just a stupid rock.
Homer: Uh-huh.Lisa: But I don't see any tigers around here, do you?
[pause]Homer: Lisa, I want to buy your rock!
[A moment's hesitationand money changes hands.] (From
The Simpsons
Much
Apu About Nothing .)If Lisa isn't around, who will identify specious reasoning for us? We can certainly use her approach of finding other particular examplesthat follow the same argument, yet lead to a clearly erroneous conclusion.
Suppose that my friend makes the following argument:
| 1 | Warm cola tastes bad. | Premise |
| 2 | Warm salt-water tastes bad. | Premise |
| 3 | Therefore, mixing them together tastes bad. | Common-sense conclusion, lines 1,2 |
| 1 | Ice-cold coke tastes good. | Premise |
| 2 | Ice coffee tastes good. | Premise |
| 3 | Therefore, mixing them together tastes good. | Common-sense conclusion, lines 1 and 2. |
My friend responds by claiming that thecommon-sense conclusionis too valid; the rule is that bad-taste is preserved upon mixing,not that any taste is preserved. While I'm inclined to believe that, we realize we can stilltest this more refined rule: can you come up with an instance of mixing together bad-tasting thingsand ever getting a yummy result? (Say, salt and flour, which can be mixed and baked to get delicious saltines!The argument continues, about whether the form of the argument precludes baking, and so on.)
The end result (after I take some antacid) is that we have a clearer understanding ofthe initially vaguecommon-sense conclusion, and stricter rules about when it applies.Thus, refining the argument has led us to a greater understanding.
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