Section 2.3 I, Robot Mind as Software

Functionalism Mental states are functional states. To perform a function is to take a certain input and produce a certain output. When two things perform the same function, they are said to have the same “causal role.” The problem with this description is that it makes functionalism easy to confuse with both logical behaviorism and identity theory. 2

A functional description of a heating system http://www. mind. ilstu Give heat as output only if the temperature is less than 68 degrees. 3

A functional description of a heating system (at a more concrete level) 4

A functional description of a heating system (at an even more concrete level) 5

Now, consider just the first component of the function system Now, suppose we just consider the the thermometer. We might have an interest in the physical properties of the thermoeter, but we might not. We might instead be interested solely in the thermoeter functional properties. 6

Functionalism A thermometer is functionally defined as a device which measures temperature. Some physical change occurs in the thermometer and this physical change is converted into a readable value. We can imagine a black box which encloses the thermostat, hiding it from view. We can then do for the thermostat, what we had initially done for the entire heating system -- we can give a functional description of the thermostat. 7

Functionalism A functional description is concerned only with what it takes as input and what it gives as output, ignoring completely how it succeeds in performing that function. The function of a thing is often called its causal role. Given that there are many ways to build a thermostat that performs the "temperature detecting" function, we say that a thermostat can be realized in many different ways. 8

Functionalism 9

Artificial Intelligence The goal of artificial intelligence research is to create a machine that can think for itself; that has a mind of its own. According to “strong AI,” there’s nothing more to having a mind than running the right kind of program. Strong AI claims that the mind is to the brain as the software of a computer is to its hardware. Mental States are functional states To have a mind is to have the right kind of program being run on sufficiently rich and stable hardware.

Functionalism How is functionalism different from identity theory. Multiple Realizability Problem. How is functionalism different from logical behaviorism? 11

Frank Tipler Why would this view be important if it were true? Would would hinge on it?

Thought Experiment: Lewis’s Pained Madman

Functionalism and Feeling If functionalism were true, it would be impossible for someone to be in pain and function differently than we do when we are in pain. But, as Lewis’s pained madman shows, it’s not impossible for someone to be in pain and function differently than we do. So, functionalism is false; being in a certain functional state is not a necessary condition for being in a mental state.

Thought Experiment: Block’s Chinese Nation “Suppose we convert the government of China to functionalism, and we convince its officials that it would enormously enhance their international prestige to realize a human mind for an hour.” Suppose the people of China run a mind program. Would there now be another mind on Earth? This is known as the “absent qualia objection” to functionalism.

Block’s Argument If functionalism were true, then anything that had the right sort of functional organization would have a mind. But as Block’s Chinese nation shows, it is not the case that anything that had the right sort of functional organization would have a mind. So functionalism is false; having the right sort of functional organization is not a sufficient condition for having a mind.

Thought Experiment: Putnam’s Inverted Spectrum “Imagine your spectrum becomes inverted at a particular time in your life and you remember what it was like before that.” Imagine further that you learn to function as before.

Putnam’s Argument 1. If functionalism were true, it would be impossible for people with the same functional organization to have different mental states. 2. But, as Putnam’s inverted spectrum shows, it’s not impossible for people with the same functional organization to have different mental states. 3. So functionalism is false; having a certain functional organization is not a sufficient condition for being in a certain mental state.

Thought Experiment: The Turing Test

Thought Experiment: Searle’s Chinese Room

Searle’s Argument If a computer could understand a language solely in virtue of running a program, then the man in the room would understand Chinese (because he’s doing the same thing that a computer does, namely, manipulating symbols in accordance with a set of rules.) But the man in the room doesn’t understand Chinese. So computers can’t understand a language solely in virtue of running a program.

Syntax and Semantics How a symbol can be combined with other symbols to form a sentence is determined by its syntax. What a symbol means is determined by its semantics.

Replies to the Chinese Room: Systems reply: the man in the room doesn’t understand Chinese, but the whole system does. Robot reply: the man in the room doesn’t understand Chinese, but if the room were put in a robot, the robot would. Brain simulator reply: the man in the room doesn’t understand Chinese, but if the program simulated nerve firings, the system would. Combination reply: even if each of the above replies is inadequate, taken together they would create a system that understands Chinese.

Intentionality Intentionality is the property of being of or about something. Mental states have intentionality because they can be of or about something. The belief that the Yankees will win the pennant, for example, is about the Yankees, the pennant, and the proposition that the Yankees will win the pennant.