Question

1. After doing the textbook (Rachels) reading, and reading John Searle’s article, how would you, in your own words, summarize the basic arguments of the Mind-Brain Identity Theory? What are the basic arguments here (and make specific reference to the readings in your answer)?

2. In general, as you described it in Question #1 above, do you find yourself agreeing or disagreeing with “Mind-Brain Identity Theory” as an explanation for subjective experiences? Explain why (and remember that when assessing arguments, you are examining the logic and evidence).

3. Here is another relevant TedTalk. This one relates back to the “split-brain” experiences you read about for Wednesday. It’s a fascinating talk by brain researcher Jill Bolte Taylor, discussing her own such “split-brain” experience (as the result of a stroke).

After watching the video, can you, in your own words, relate Taylor’s experiences to the discussion of personal identity and mind-body? What do her experiences say to each of these issues? Do they seem to support specific theories, such as Bundle Theory and Mind-Brain Identity Theory? Explain why, or why not.

Answer 1

The mind-brain identity theory (or identity thesis) is a concept that says mental states/events/processes are identical to brain states/events/processes. The type identity theory (often called just the "identity theory") says that mental types are physical types, while the token identity theory says that mental tokens are physical tokens. Over the years the thesis has been successively understood as involving a contingent identity relation, an analytic identity relation, and then an posteriori necessary identity relation. The most common objection to the type identity theory is the objection from multiple realizability.

This is the most basic explanation of the mind brain identity theory. Now we come to John Searle's theory.

1. In the early days of artificial intelligence research, some cognitive scientists were making extravagant claims about computer programs that could supposedly interpret stories in novels the same way that humans do. Like us, the computer could supposedly draw from life experiences to help understand the events described in a story. American philosopher John Searle did not believe these claims and he offered a now-famous thought experiment against the whole idea of strong artificial intelligence.

             Imagine that I am in a room by myself and am assigned the task of responding to questions written on slips of paper in Chinese. I do not know Chinese, but I have rulebooks for manipulating Chinese characters. So if I get a slip of paper with something written on it, I consult the rulebooks to see what I should put down in response. I eventually master the technique of manipulating the Chinese symbols and my answers to the questions are absolutely indistinguishable from those of native Chinese speakers. All the while, though, I do not understand a single word of Chinese. This, according to Searle, is what is going on in the most sophisticated computers: we ask the computer probing questions about a novel, and the computer gives us subtle answers. On the outside the computers may appear to think like humans do. On the inside, though, they are just mechanically following rulebooks for manipulating symbols. In short, computers do not actually have strong artificial intelligence, even if they appear that way.

             Searle's Chinese Room experiment has generated many critical responses from defenders of strong artificial intelligence. One criticism is that Searle is only exposing flaws with the Turing Test for artificial intelligence, but he does not expose problems with the possibility of strong artificial intelligence itself. To explain, Searle's Chinese Room scenario is set up as a Turing Test for whether someone understands Chinese. According to this Chinese Turing Test, if the thing inside the room responds like a Chinese speaker, then the thing must be a Chinese speaker. Searle correctly objects that this Chinese Turing Test places too much weight on a thing's skills, without considering what is going on inside that thing. However, the critic argues, this does not warrant the extreme conclusion that no computer can have strong artificial intelligence. A more modest conclusion is that the Turing Test itself is flawed, and there is no easy test to determine whether a computer truly has strong artificial intelligence.

             Ultimately, Searle holds a skeptical view about strong artificial intelligence ever becoming a reality. At our current stage of technology, he argues, only biological brains are capable of having mental states. He agrees with identity theorists that the human mind is imbedded in brain activity, but doubts the functionalist claim that those patterns of activity can also occur in computers. He argues that there is something unique about the physical construction of human brains that allows for the creation of conscious thought, which may never be capable of occurring in silicon microchips. He does not entirely rule this out as a possibility for the future, but is doubtful about it ever occurring.

2. I agree with the Mind Brain Identity Theory as an explanation for subjective experiences. There are two constructive criticisms but there

The first one is Multiple Realizability thesis asserts that mental states can be realized in multiple kinds of systems, not just brains, for example. Since the identity theory identifies mental events with certain brain states, it does not allow for mental states to be realized in organisms or computational systems that do not have a brain. This is in effect an argument that the identity theory is too narrow because it does not allow for organisms without brains to have mental states. However, token identity (where only particular tokens of mental states are identical with particular tokens of physical events) and functionalism both account for multiple realizability.  The response of type identity theorists, such as Smart, to this objection is that, while it may be true that mental events are multiply realizable, this does not demonstrate the falsity of type identity. The fundamental point is that it is extremely difficult to determine where, on the continuum of first order processes, type identity ends and merely token identities begin. Whether we say that two things are of the same type or are tokens of the same type because of subtle differences is just a matter of descriptive abstraction. The type-token distinction is not all or nothing.

Another frequent objection is that type identity theories fail to account for phenomenal mental states (or qualia), such as having a pain, feeling sad, experiencing nausea. Arguments can be found in Saul Kripke and David Chalmers, for example, according to which the identity theorist cannot identify phenomenal mental states with brain states (or any other physical state for that matter) because one has a sort of direct awareness of the nature of such qualitative mental states, and their nature is qualitative in a way that brain states are not.

3. In December of 1996, Harvard trained neuroanatomist Jill Bolte Taylor was given the “opportunity” to study her own right brain in action when a blood vessel in her left brain exploded and over the course of 4 hours, virtually destroyed that entire hemisphere. She became, as she said after her recovery, “an infant in a woman’s body.” Even more extraordinary, though, was her spiritual transformation.

Taylor’s road to recovery is as remarkable as her experience of left brain death. Needless to say, she had no personal desire to return to her old way of perceiving the world, but wanted to share her revelation with the world. After a blood clot the size of a golf ball was removed from the left side of her brain, she began an eight year journey back into the little “I am” of her ego.

Jill Bolte Taylor and others argue that our Western conditioning leads us to lean towards the limited vision of the left brain. At the same time, they see its value for survival and communication. The key, they say, is to restore balance between the hemispheres and see both the big picture and be able to make a positive contribution to the world.

Her split brain theory supports the bundle theory because:

a. Parfit and the Bundle Theory claim that there is no “person” involved

b. Different awareness of events occurring at the same time, not different egos

c. True for both split-brain patients and people with normal brains