The idea of the brain as an information processor—a machine manipulating blips of energy according to fathomable rules—has come to dominate neuroscience. However, one enemy of the brain-as-computer metaphor is John R. Searle, a philosopher who argues that since computers simply follow algorithms, they cannot deal with important aspects of human thought such as meaning and content. Computers are syntactic, rather than semantic, creatures. People, on the other hand, understand meaning because they have something Searle obscurely calls the causal powers of the brain.
Yet how would a brain work if not by reducing what it learns about the world to information—some kind of code that can be transmitted from neuron to neuron? What else could meaning and content be? If the code can be cracked, a computer should be able to simulate it, at least in principle. But even if a computer could simulate the workings of the mind, Searle would claim that the machine would not really be thinking; it would just be acting as if it were. His argument proceeds thus: if a computer were used to simulate a stomach, with the stomach's churnings faithfully reproduced on a video screen, the machine would not be digesting real food. It would just be blindly manipulating the symbols that generate the visual display.
Suppose, though, that a stomach were simulated using plastic tubes, a motor to do the churning, a supply of digestive juices, and a timing mechanism. If food went in one end of the device, what came out the other end would surely be digested food. Brains, unlike stomachs, are information processors, and if one information processor were made to simulate another information processor, it is hard to see how one and not the other could be said to think. Simulated thoughts and real thoughts are made of the same element: information. The representations of the world that humans carry around in their heads are already simulations. To accept Searle's argument, one would have to deny the most fundamental notion in psychology and neuroscience: that brains work by processing information.
1. The main purpose of the passage is to
(A) propose an experiment
(B) analyze a function
(C) refute an argument
(D) explain a contradiction
(E) simulate a process
2. Which of the following is most consistent with Searle's reasoning as presented in the passage?
(A) Meaning and content cannot be reduced to algorithms.
(B) The process of digestion can be simulated mechanically, but not on a computer.
(C) Simulated thoughts and real thoughts are essentially similar because they are composed primarily of information.
(D) A computer can use "causal powers" similar to those of the human brain when processing information.
(E) Computer simulations of the world can achieve the complexity of the brain's representations of the world.
3. The author of the passage would be most likely to agree with which of the following statements about the simulation of organ functions?
(A) An artificial device that achieves the functions of the stomach could be considered a valid model of the stomach.
(B) Computer simulations of the brain are best used to crack the brain's codes of meaning and content
(C) Computer simulations of the brain challenge ideas that are fundamental to psychology and neuroscience.
(D) Because the brain and the stomach both act as processors, they can best be simulated by mechanical devices.
(E) The computer's limitations in simulating digestion suggest equal limitations in computer-simulated thinking.
4. It can be inferred that the author of the passage believes that Searle's argument is flawed by its failure to
(A) distinguish between syntactic and semantic operations
(B) explain adequately how people, unlike computers, are able to understand meaning
(C) provide concrete examples illustrating its claims about thinking
(D) understand how computers use algorithms to process information
(E) decipher the code that is transmitted from neuron to neuron in the brain
5. From the passage, it can be inferred that the author would agree with Searle on which of the following points?
(A) Computers operate by following algorithms.
(B) The human brain can never fully understand its own functions.
(C) The comparison of the brain to a machine is overly simplistic.
(D) The most accurate models of physical processes are computer simulations.
(E) Human thought and computer-simulated thought involve similar processes of representation.
6. Which of the following most accurately represents Searle's criticism of the brain-as-computer metaphor, as that criticism is described in the passage?
(A) The metaphor is not experimentally verifiable.
(B) The metaphor does not take into account the unique powers of the brain.
(C) The metaphor suggests that a brain's functions can be simulated as easily as those of a stomach.
(D) The metaphor suggests that a computer can simulate the workings of the mind by using the codes of neural transmission.
(E) The metaphor is unhelpful because both the brain and the computer process information.