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  • 1. PHIL 160 PHIL 160 "Explanation"
  • 2. PHIL 160 Goals of science: predictions manipulations explanations What is required for a good explanation?
  • 3. Prediction vs. Explanation PHIL 160 What will happen next? Why did it happen? Prediction: Explanation:
  • 4. PHIL 160 Why did it have to happen? How is it possible for this to happen? Why did this happen rather than something else? Why did it happen?
  • 5. Deductive-Nomological model PHIL 160
    • An explanation is a deductive argument.
    • Conclusion = fact to be explained.
    • Premises include a “law of nature” (universal regularity).
    (from “nomos”, Greek for “law”)
  • 6. Why is this bird black? PHIL 160
    • This bird is a raven.
    • All ravens are black.
     This bird is black.
  • 7. Deductive-Nomological model PHIL 160
    • Reduce explanations from one theory to equivalent explanations in terms of another theory.
    • Explanation shed light on what’s really happening.
    • Often requires “bridge laws”.
    at work in “ intertheoretic reduction”
  • 8. PHIL 160
  • 9. PHIL 160
  • 10. Why does the pressure of this gas sample increase? PHIL 160
    • The volume of the gas sample is decreased.
    • 2. Boyle’s law: PV= k .
     The pressure of the gas sample increases.
  • 11. Kinetic Theory of Gases: PHIL 160
    • A gas is a collection of point particles:
    • occupying negligible volume.
    • in constant motion through entire container.
    • undergoing elastic collisions with walls of container and other particles.
  • 12. PHIL 160
  • 13. “ Bridge Laws” PHIL 160 Volume = space through which point particles are moving Pressure = force from collisions with walls/area Temperature = measure of the kinetic energy of the particles.
  • 14. PHIL 160
  • 15. PHIL 160 Volume of the gas sample is decreased (less space for particles to move through). Why does the pressure of this gas sample increase?
  • 16. Why does the pressure of this gas sample increase? PHIL 160 Same number of particles with same kinetic energy  more frequent collisions with walls.
  • 17. PHIL 160 More frequent collisions with walls  higher force/area (i.e., higher pressure) Why does the pressure of this gas sample increase?
  • 18. Does D-N model work for all explanations? PHIL 160
    • Is every argument that fits the model a good explanation?
    • Does every good explanation fit the model?
  • 19. PHIL 160  Alex didn’t get pregnant. Why didn’t Alex get pregnant?
    • Alex takes birth control pills daily according to the instructions.
    • Taken according to instructions, birth control pills are 99.9% effective at preventing pregnancy.
  • 20. PHIL 160
  • 21. Why did the salt dissolve? PHIL 160
    • I hexed the salt.
    • I put the (hexed) salt in water.
    • Hexed salt dissolves in water.
     The salt dissolved.
  • 22. PHIL 160
    • I put the salt in water.
    • Salt dissolves in water.
     The salt dissolved. Hexing is not explanatorily relevant! Why did the salt dissolve?
  • 23. Why did Nancy get lung cancer? PHIL 160
    • Nancy has smoked 2 packs of cigarettes a day for 10 years.
    • Smoking 2 packs of cigarettes a day for 10 years causes lung cancer.
     Nancy got lung cancer.
  • 24. PHIL 160 Smoking 2 packs of cigarettes a day for 10 years causes lung cancer. Not for every smoker! Not a law of nature. Why did Nancy get lung cancer?
  • 25. PHIL 160
  • 26. Why did these camellias die? PHIL 160
    • The camellias were planted in hot, rich soil.
    • Hot soil damages camellia roots.
     These camellias died.
  • 27. Why did these camellias thrive? PHIL 160
    • The camellias were planted in hot, rich soil.
    • Camellias grow well in rich soil.
     These camellias thrived.
  • 28. Cartwright : We don’t need a law! PHIL 160 We don’t need to know a law of nature to explain the camellias dying or thriving. There might be no such law of nature! (Explanation is still good.)
  • 29. PHIL 160
  • 30. Why is the flagpole’s shadow 4 meters long? PHIL 160
    • Flagpole is 3 m high.
    • Sunlight strikes pole at angle  .
    • Shadow length =
    • height of pole x tan  .
     Shadow length = 4 m.
  • 31. Good deductive argument, BAD explanation! PHIL 160
    • Shadow length is 4 m.
    • Sunlight strikes pole at angle  .
    • Shadow length =
    • height of pole x tan  .
     Height of pole = 3 m.
  • 32. PHIL 160 What kind of explanations in science? Looking for universal regularities or statistical regularities? Possible mechanisms or how it actually happened? (Causes, or something else?)

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