1 / 13

Induction

Induction. What is Good Evidence?. You are studying emerald samples from all over the world for your geology class.

reba
Download Presentation

Induction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Induction What is Good Evidence?

  2. You are studying emerald samples from all over the world for your geology class. “This Columbian emerald is green…this South African emerald is green … this Thai emerald is green…I’ve looked at samples of emeralds from 25 countries so far. They’re all green. I’m starting to think that ALL emeralds are green.” “I’m sorry,” your friend says, “Your samples actually show that all emeralds are GRUE.” “What are you talking about?” you ask. “Are you color blind?”

  3. “Not at all. The evidence you have that emeralds are green is also evidence that emeralds are grue. An object is grue if it looks green prior to April 1, 2020, and blue after that date. You have just sampled emeralds from 25 countries and found that they were all grue.” “But that’s just crazy,” you say. “There’s nothing in what I see looking at these emeralds that tells me that they will be blue after April 1, 2020!” “Well,” says your friend slyly, “What is there in what you see that tells you they will still be green after April 1, 2020?”

  4. An example of Deductive Logic : If the Premises of a good deductive argument are true, the conclusion must also be true. Such an argument is said to be valid. Premise #1: All bachelors are unmarried. Premise #2: Bill is a bachelor. Conclusion: Bill is unmarried.

  5. An example of Inductive Logic : The Premises of a good inductive argument are good evidence that the conclusion is true. Nevertheless, the conclusion could be false. Premise #1: Emerald #1 from India is green. Premise #2: Emerald #2 from Thailand is green.. Premise #25: Emerald #25 from South Africa is green.. Conclusion: All emeralds are green.

  6. An example of Inductive Logic : However, if the samples come from many regions and many different geologic formations, we may find the evidence to be very compelling! Premise #1: Emerald #1 from India is green. Premise #2: Emerald #2 from Thailand is green.. Premise #25: Emerald #25 from South Africa is green.. Conclusion: All emeralds are green.

  7. Problems with Induction The Grue Paradox An object is GRUE if it appears green before April 1, 2020, and blue after that date. All the observations we make which support the conclusion that emeralds are green provide equally good evidence that emeralds are grue!

  8. Problems with Induction The Paradox Extended An object is GRED if it appears green before April 1, 2020, and blue after that date. An object is GRELLOW if it appears green before April 1, 2020, and yellow after that date. All the observations we make which support the conclusion that emeralds are green provide equally good evidence that emeralds are gred or grellow!

  9. Problems with Induction It Gets Even Worse... An object is GRED2 if it appears green before April 2, 2020, and blue after that date. An object is GRELLOW3 if it appears green before April 3, 2020, and yellow after that date. All the observations we make which support the conclusion that emeralds are green provide equally good evidence that emeralds are gred2 or grellow3!

  10. Some philosophical theories Inductive Skepticism We can never have convincing evidence that a statement like “All emeralds are green” is true. Since inductive arguments are not deductively valid, we should not allow ourselves to be convinced by them. We may make use of generalizations like “All emeralds are green” – we may order an emerald necklace to go with a green dress, assuming that the emeralds will be green. But we should always be prepared for our assumptions to turn out to be false. They might turn blue!

  11. Some philosophical theories Inductive Pragmatism The truth is what it is most useful to believe. We could reject deductively valid arguments if we found it useful to do so. And we can accept inductive argumentsas conclusive if it is useful. We haven’t found it useful to believe that objects change color spontaneously. So we reject the conclusion that emeralds are grue. If it turned out to be useful to believe emeralds are grue, we reserve the right to reconsider!

  12. Some philosophical theories Enter Quality! Like a quality work of art, a quality conclusion is simple and elegant. Nothing in our sensory experience shows us that objects are not grue or gred or grellow. We are guided by Quality when we conclude that emeralds are green, and reject the infinitely many alternative conclusion that they are grue, gred, etc.

  13. Continue your journey... Assignments Read Part III of ZMM ZMM PDF Sections 16 - 26 Reading Quiz on Monday, May 26

More Related