1. Some Methods and Interests

2. Argument Argument is at the heart of philosophy Argument is at the heart of philosophy It is the only method for getting results It is the only method for getting results The nature of the method is also of interest The nature of the method is also of interest We seek abstract knowledge of arguments We seek abstract knowledge of arguments Allows knowledge of particular arguments Allows knowledge of particular arguments Is studied in Logic (Formal and Informal) Is studied in Logic (Formal and Informal)

3. Argument Let’s look at how we talk about arguments Let’s look at how we talk about arguments This will make future discussions less scary as the way we discuss things will be familiar to you This will make future discussions less scary as the way we discuss things will be familiar to you And will leave you able to follow the content of the discussion without having to struggle with the form And will leave you able to follow the content of the discussion without having to struggle with the form

4. Argument Deductive arguments Deductive arguments Socrates is a man All men are mortal ------------------------ Socrates is mortal In a valid deductive argument, if the premisses are true then the conclusion must be true In a valid deductive argument, if the premisses are true then the conclusion must be true

5. Argument Inductive arguments Inductive arguments Swan number 1 is white Swan number 2 is white ------------------------ All swans are white In a strong inductive argument, if the premisses are true it makes the conclusion probably true In a strong inductive argument, if the premisses are true it makes the conclusion probably true

6. Logic Matters The argument in the Euthyphro was basically this: The argument in the Euthyphro was basically this: 1. 1. Socrates gets from Euthyphro a definition of ‘piety:’ Piety is what the gods love and impiety what the gods hate. 2. 2. Socrates then derives certain consequences of this definition. Specifically: the same things are both pious and impious 3. 3. Finally deriving the conclusion that: Piety is not what the gods love nor impiety what they hate.

7. Logic Matters I claim this involves an argument of the form I claim this involves an argument of the form If A then B Not B Not A This form is called modus tollens This form is called modus tollens Let’s look at this form Let’s look at this form

8. Logic Matters Here’s an example Here’s an example If A then B Not B Not A

9. Logic Matters Here’s an example Here’s an example If it has rained then the grass is wet Not B Not A

10. Logic Matters Here’s an example Here’s an example If it has rained then the grass is wet The grass is not wet Not A

11. Logic Matters Here’s an example Here’s an example If it has rained then the grass is wet The grass is not wet It has not rained This is a valid argument This is a valid argument If the reasons are true the conclusion must be true If the reasons are true the conclusion must be true

12. Logic Matters Here’s another example Here’s another example If A then B Not B Not A

13. Logic Matters Here’s another example Here’s another example If Socrates is a man then he is mortal Not B Not A

14. Logic Matters Here’s another example Here’s another example If Socrates is a man then he is mortal Socrates is not mortal Not A

15. Logic Matters Here’s another example Here’s another example If Socrates is a man then he is mortal Socrates is not mortal Socrates is not a man This is still a valid argument This is still a valid argument If the reasons are true the conclusion must be true If the reasons are true the conclusion must be true

16. Logic Matters Any modus tollens argument is a valid argument Any modus tollens argument is a valid argument It is a valid form It is a valid form Why do we say the Euthyphro argument was modus tollens? Why do we say the Euthyphro argument was modus tollens? Because it looks like this: Because it looks like this:

17. Logic Matters If piety is what is loved by the gods then the same things are both pious and impious. The same things are not both pious and impious

18. Logic Matters If piety is what is loved by the gods then the same things are both pious and impious. The same things are not both pious and impious Piety is not what is loved by the gods

19. Logic Matters If piety is what is loved by the gods then the same things are both pious and impious. The same things are not both pious and impious Piety is not what is loved by the gods We know the second premise is true We know the second premise is true Because we know any contradiction must be false Because we know any contradiction must be false

20. Logic Matters If piety is what is loved by the gods then the same things are both pious and impious. The same things are not both pious and impious Piety is not what is loved by the gods We know the first premise is true We know the first premise is true Because we agreed to each step of the argument that derived the ‘then’ part from the ‘if’ part Because we agreed to each step of the argument that derived the ‘then’ part from the ‘if’ part

21. Logic Matters If piety is what is loved by the gods then the same things are both pious and impious. The same things are not both pious and impious Piety is not what is loved by the gods We know the conclusion is true We know the conclusion is true Because we see that the argument is modus tollens and we know it has true premises Because we see that the argument is modus tollens and we know it has true premises

22. Science Matters This kind of argument has a role in Science This kind of argument has a role in Science It is part of the method that scientists use to seek answers to such questions as It is part of the method that scientists use to seek answers to such questions as Why do needles point north? Why do needles point north? Why do sticks bend going into water? Why do sticks bend going into water? Why does water boil when heated? Why does water boil when heated? Science has earned great respect as a way of getting at the truth of things Science has earned great respect as a way of getting at the truth of things So its methods should be valued So its methods should be valued

23. Science Matters How do scientists seek answers for questions about the world? How do scientists seek answers for questions about the world? They apply the Hypothetico-Deductive Method They apply the Hypothetico-Deductive Method 1. 1. Form a hypothesis 2. 2. Deduce testable consequences from the hypothesis 3. 3. Test for these consequences 4. 4. Confirm or disconfirm the hypothesis

24. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. Form a hypothesis 2. 2. Deduce testable consequences from the hypothesis 3. 3. Test for these consequences 4. 4. Confirm or disconfirm the hypothesis

25. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. There were land bridges across the oceans 2. 2. Deduce testable consequences from the hypothesis 3. 3. Test for these consequences 4. 4. Confirm or disconfirm the hypothesis

26. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. There were land bridges across the oceans 2. 2. There would be remains of those bridges 3. 3. Test for these consequences 4. 4. Confirm or disconfirm the hypothesis

27. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. There were land bridges across the oceans 2. 2. There would be remains of those bridges 3. 3. There is no evidence of these bridges 4. 4. Confirm or disconfirm the hypothesis

28. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. There were land bridges across the oceans 2. 2. There would be remains of those bridges 3. 3. There is no evidence of these bridges 4. 4. Land bridges didn’t cross the oceans

29. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. Form another hypothesis 2. 2. Deduce testable consequences from the hypothesis 3. 3. Test for these consequences 4. 4. Confirm or disconfirm the hypothesis

30. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. The continents were previously joined but split up 2. 2. Deduce testable consequences from the hypothesis 3. 3. Test for these consequences 4. 4. Confirm or disconfirm the hypothesis

31. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. The continents were previously joined but split up 2. 2. The continents are moving 3. 3. Test for these consequences 4. 4. Confirm or disconfirm the hypothesis

32. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. The continents were previously joined but split up 2. 2. The continents are moving 3. 3. Measurements show that they are moving 4. 4. Confirm or disconfirm the hypothesis

33. Science Matters Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? Example: Why do we sometimes see the same collections of fossilized plants and animals on opposite sides of oceans? 1. 1. The continents were previously joined but split up 2. 2. The continents are moving 3. 3. Measurements show that they are moving 4. 4. The continents could have split up

34. Science Matters The similarity of the Hypothetico-Deductive Method and the method of elenchus is clear The similarity of the Hypothetico-Deductive Method and the method of elenchus is clear The method is not what distinguishes Philosophy The method is not what distinguishes Philosophy Philosophers see themselves as engaged in the same pursuit of truth as the scientists Philosophers see themselves as engaged in the same pursuit of truth as the scientists

35. Science Matters Philosophy is prior to science in that pursuit Philosophy is prior to science in that pursuit Many scientific topics were originally philosophical Many scientific topics were originally philosophical physics, astronomy, cosmology, chemistry, biology, … When do they become sciences rather than philosophies? When they begin to ask questions whose answers can be found by inspecting the world Philosophy is needed to discover which parts of a topic asks questions that can be answered in that way

36. Conceptual clarity So what does philosophy do if it doesn’t ask questions that the world can answer? So what does philosophy do if it doesn’t ask questions that the world can answer? It clarifies concepts and allows other methods of enquiry to go forward. Science depends on this. It clarifies concepts and allows other methods of enquiry to go forward. Science depends on this.

37. Conceptual clarity Example 1. Example 1. The Greeks couldn’t see how motion was possible The Greeks couldn’t see how motion was possible For something to move everything at the destination must move For something to move everything at the destination must move For everything at the destination to move there must be somewhere to go where there is nothing For everything at the destination to move there must be somewhere to go where there is nothing But everywhere there is something But everywhere there is something So motion is impossible So motion is impossible We think this argument is nonsensical. Why did the Greeks have problems? We think this argument is nonsensical. Why did the Greeks have problems?

38. Conceptual clarity Example 1. Example 1. The Greeks did not distinguish space and matter The Greeks did not distinguish space and matter We think of matter as occupying space We think of matter as occupying space They thought of matter as constituting space They thought of matter as constituting space They conceived of space and matter as being like a brick wall They conceived of space and matter as being like a brick wall Where there was no matter there was not empty space: there was just nothing Where there was no matter there was not empty space: there was just nothing

39. Conceptual clarity Example 2. Example 2. Early scientists couldn’t ‘understand’ Newton’s force of Gravity Early scientists couldn’t ‘understand’ Newton’s force of Gravity For one body to cause a change in another there must be contact For one body to cause a change in another there must be contact The moon and the earth are not in contact so neither could affect the other The moon and the earth are not in contact so neither could affect the other So Gravity is impossible So Gravity is impossible

40. Conceptual clarity Example 3. Example 3. We don’t ‘understand’ the nature of matter We don’t ‘understand’ the nature of matter Sometimes it behaves like particles Sometimes it behaves like particles Other times it behaves like waves Other times it behaves like waves It isn’t just ambiguity It isn’t just ambiguity Matter seems to be aware of the situation it is in and behaves appropriately Matter seems to be aware of the situation it is in and behaves appropriately That is absurd, and yet: That is absurd, and yet:

41. Conceptual clarity There’s a more basic reason to value clear and well-formed concepts There’s a more basic reason to value clear and well-formed concepts We are intentional actors We are intentional actors We act rationally on our beliefs in order to satisfy our desires We act rationally on our beliefs in order to satisfy our desires To apply reason to our beliefs and desires these need to be concepts To apply reason to our beliefs and desires these need to be concepts To be successful intentional actors our concepts need to be clear and well-formed To be successful intentional actors our concepts need to be clear and well-formed