1. According to the Mind/Brain Identity Theory, do mentalistic terms like “belief” or “pain” compete with physical terms like “neuronal impulse” or “synaptic cleft”? Should we aim to preserve the use of both mental terms and physical terms? Why or why not? 

2. Reconstruct Descartes’ first argument for dualism. Is it valid? If not, why not? (Are the premises true? Is the conclusion true? Explain your answers.) 

3. Descartes’ first and second arguments for dualism both appeal to the same principle: namely, Leibniz’s Law. Will the same objection suffice to undermine both? If not, why not? 

4. What is a propositional attitude? Give three examples that aren’t discussed above. 

5. Consider the following set of propositions: (1) “Linda remembers receiving an autograph from Muhammad Ali.” (2) “Linda does not remember receiving an autograph from Cassius Clay.” • Do these propositions contain any reference to propositional attitudes? If so, which? • Do these propositions attribute any properties to objects? If so, which objects? • What conclusion, if any, can you derive from these two propositions? (Does it follow that Muhammad Ali and Cassius Clay are different people? 

6. Descartes says that he can conceive of himself being a disembodied spirit (that is, having a mind but not a body). What does conceiving of something mean? Does Descartes’ claim entail that it is possible for him to be a disembodied spirit? (See discussion of conceivability and possibility in Chapter 8.) 

7. Is a statue identical with the stone it is made of? Is an organism identical with the collection of cells in its body? Can Leibniz’s Law be used to show that either of these claims of identity is false? 

8. In the Sixth Meditation, Descartes argues that he is essentially a thinking thing. An essential property of a thing is a property that the thing must have if it is to exist. Could Descartes be deprived of thought and still be Descartes? Could Descartes have been born without the capacity of thought and still be Descartes? If Descartes can’t doubt that he thinks, is that enough to show that Descartes is essentially a thinking thing? 

9. It was suggested in this chapter that we understand causality best when there is a physical signal that passes from cause to effect (the electricity example). However, the fact that “absences” sometimes cause suggests that causality need not involve a physical signal. For example, suppose a patient dies because his doctor fails to give him medicine. There is no “physical signal” between the doctor and patient in this case, but there is causation. Does this point solve the objection to dualism that concerns the nature of causality?

10. Would the discovery of perfect correlations between certain mental events and physical events (say, between experiences of pain and c-fiber firings) be evidence against dualism? Why or why not? 

11. What are the two central arguments that advocates of the Mind/Brain Identity thesis typically appeal to when defending their position? 

12. Why might someone doubt that the Principle of Uniformity is a surefire guide to which theories we should pursue? Do you think this skepticism is well-founded, or is it just another example of philosophers’ penchant for “radical doubt”? 

13. Suppose we observe a perfect correlation between some mental property (like feeling pain) and some physical property (like having one’s c-fibers fire). Apply the Surprise Principle (Chapter 3) to see whether this observation strongly favors the identity theory over dualism. 

14.In the passage from Principles of Natural Philosophy quoted in this chapter, Newton defends the Principle of Parsimony by saying that “Nature does nothing in vain.” Is this idea consistent with what we now know about natural selection (Chapter 6)? 

15. The Principle of Parsimony is often thought to be relevant to the question of whether God exists. Formulate and evaluate an argument for atheism that makes use of this principle. 

16. On the companion website, the psychologist U. T. Place defends the identity theory, but does not mention the Principle of Parsimony. He does so by describing a situation in which the correlation between two events justifies the conclusion that the two are identical. Evaluate Place’s argument.

17. What would it mean for something to be a first cause without being God? What would it mean for something to necessarily exist without being God 

18. Aquinas seems to commit the Birthday Fallacy when he argues that, if every natural event has a cause, then there must be one “first cause.” Why is this line of reasoning fallacious? Can you think of another example of the Birthday Fallacy? 

19. Why does Aquinas think that it is “inconceivable” that the world is infinitely old? Do you think his argument is plausible? Why or why not? 

20. Why, if at all, do you think it might be helpful to reflect on unsuccessful arguments for the existence of God? Explain your answer. 

21. Which of the four arguments discussed above do you find most convincing? Why? Problems for Further Thought 

1 I formulated Aquinas’s proofs by having him talk about objects that exist in “nature” (in “the natural world”). What does “nature” include? Does it include just the things we can see or hear or touch or taste or smell? 

2 In discussing Aquinas’s third proof, I talked about Charlie the atom as an example of a thing that is both eternal and contingent. Could something exist that is both necessary and noneternal? It would exist at some time in each possible world, though it would not exist at all times in the actual world. Can you give an example of such a thing? 

3 I criticized Aquinas’s third argument by discussing numbers, which I claimed exist necessarily. Can the argument be reformulated so that this objection no longer applies? 

4 I criticized Aquinas’s fourth argument by discussing “maximum stupidity.” Can Aquinas reply to this objection by claiming that stupidity is just the absence of intelligence?