Weak Analogy
Form: A is like B.
B has property P.
Therefore; A has property P.
(Where the analogy between A and B is weak.)
Definition(s):
1. The fallacy of weak analogy is committed when the analogy is not strong enough to support to conclusion that is drawn.
2. Many arguments rely on an analogy between two or more objects, ideas, or situations. If the two things that are being compared aren't really alike in the relevant respects, the analogy is a weak one, and the argument that relies on it commits the fallacy of weak analogy.
Examples:
1. William Paley’s argument from design suggests that a watch and the universe are similar (both display order and complexity), and therefore infers from the fact that watches are the product of intelligent design that the universe must be a product of intelligent design too.
2. My old car was blue, and had cloth seats. It also got great gas mileage. I want to get a car with good gas mileage again, so I'm buying Mike's old Dodge Quad-Cab pickup. It's blue and has cloth seats.
3. This fossilized skeleton has a jaw bone similar to that of a horse. Its teeth are also quite similar, as is the abdominal cavity and feet. So it was probably an herbivore, like horses are.
4. Giraffes and gorillas have fur, eat plants, and have names that start with Gs. They are also very large. Guinea pigs also have a name that starts with a G, have fur, and eat plants, so they are also probably very large.
5. No one objects to a physician looking up a difficult case in medical books. So no one should object to nursing students, when taking a logic exam, being permitted to use their reference materials.
6. I had a dog that was white with brown spots, and it was the best dog I ever had. So if I buy another dog that’s white with brown spots it will be a great dog too.
7. The house I grew up in was yellow with white shutters, and I have the best memories in that house. If I buy a yellow house with white...