Answer key to homework 1 Question 1: (5 points) None of the scientists is wrong--they're each analyzing the system (human) at a different Marr level. Scientist A is talking at the hardware level because he is explaining how the system works, in terms of its machinery. Scientist B is talking at the computational level, because he is explaining what the system is doing. Scientist C is talking at the representational/algorithm level, because he is explaining how the system works, but in terms of the calculations that are happening. Question 2: (5 points) Turing's approach would have us rewrite the question as, "Can a machine BEHAVE AS THOUGH it enjoyed strawberries?" Thus we might do something like provide a machine with sweeter strawberries that humans enjoy, and sour rotten strawberries that humans dislike. If the machine accurately identifies the sweeter strawberries and the sour strawberries, and outputs a response like “Yum!” for the former and “Yuck!” for the latter, it would pass the Turing test as applied to this situation. Question 3: (3 points) To the identity theorist, the two are different because they are fundamentally different things. Only a shovel is a shovel. A stick is a stick. To the functionalist, however, the two are the same because they are doing the same thing--being used to dig stuff out of the ground. Question 4: (2 points) Many possibilities. For the linear example, on each increase the amount increased must be the same. For the exponential example, on each increase the amount increased must increase by some multiplicative rate. Question 5: (5 points) The amoeba is an intentional system because it represents changes in the world, but also desires--it will prefer to escape pain, and move towards food, for example. The speedometer is intentional, but because it lacks desires, it is not an intentional system. The car tire has neither beliefs nor desires, so is neither intentional nor an intentional system. Question 6: (5 points) (a) Physical stance--things happen because of the physics of the system. (b) Intentional stance--things happen because of how the system represents its world and the changes that happen in it. (c) Design stance--things happen because of how the system was designed to act.