Goodbye, Searle
2 comments For a long time, two types of entities shared our world. On the one hand, there were entities that had intentionality and that behaved in a way that lead us to conclude that they did, namely human beings. On the other hand, there were entities like cars and rocks that clearly did not have intentionality and that did not show behavior that could have lead us to conclude that they do. Soon there may be a third type of entities: Robots that show behavior similar to the behavior of human beings and that do neither clearly possess intentionality nor clearly not possess intentionality.
It is amazing that, after almost 30 years of philosophical discussions, John Searle’s argument against the possibility of programming a robot in a way that makes it really think is still alive. I am now going to analyze what it means for an entity to have intentionality, then give a short account of the strongest version of Searle’s thought experiment and finally argue that the only way to deny intentionality to robots on the grounds of Searle’s thought experiment is to assume a priori that intentionality is tied to biochemical processes.
Intentionality is the difference between a human being that answers questions about a story and a machine that uses a lookup table that includes all possible questions and appropriate answers. The difference between arriving at an answer by understanding the question compared to arriving at an answer by purely mechanical means is to be found not in different behavior but in the mental states that are present in the process of answering the question.
Mental states are conditions like being in pain, having the experience of seeing red, feeling love and remembering that the Statue of Liberty played an important role in a story. A mental state cannot be present without an entity that experiences the state, therefore there can be no understanding without some entity that understands. Since experience cannot be present without consciousness, the entity needs to be conscious. By definition, entities that are not conscious don’t have subjective experiences.
For very simple systems like thermostats, it is safe to assume that no understanding is involved. Even for systems that have or exceed human capacities in a specific realm, e.g. chess computers, we can assume that these systems do not have any intentionality.
Suppose we design a program that does not just represent information by means of symbols that can be identified with real-world counterparts but simulates the actual sequence of neuron firings at the synapses of a human brain. Suppose further that this program is part of brain-shaped computer that is contained within a robot that receives sensory input, e.g. through cameras, and communicates with the world by motor output in a way that is analogous to the motor capabilities we have. If the behavior that this robot shows is indistinguishable from the behavior of real human beings, should we attribute intentional states to the robot?
According to Searle, such a robot cannot have intentionality. A little man inside the robot could be receiving uninterpreted, purely syntactical symbols from the robot’s sensory receptors, he could follow fixed rules that tell him how the input symbols relate to manipulating a system of water pipes that are modeled similar to the neuronal connections of a human brain and how the result of the pipe manipulation is connected to returning other uninterpreted formal symbols to the motor mechanisms of the robot. If the man knew nothing about what the purpose of manipulating the water pipe system was, we would certainly not attribute understanding to the man.
Therefore, Searle argues, we cannot conclude that something has intentionality on the grounds that it has a certain sort of input and output and a program in between. Furthermore, we don’t have any reason to assume that intentionality has anything to do with computer programs, i.e. computational operations on purely formally specified elements, since for any program it is possible for something to instantiate that program and still not have any mental states.
Although the claim that behavior is not sufficient to make attributions of intentionality is true, it is not sufficient to conclude that no program can possibly exist that, when instantiated, has mental states. The systems view of Searle’s robot — even if the man himself has no understanding, the conjunction of man and water pipes does have understanding — sounds less absurd if you take a moment to think about how such a system would look like. In contrast to what Searle claims, it is not possible for the man operating the water pipes to internalize the formal structure of the water pipes since no system can perfectly simulate a system of comparable complexity within itself.
Even if the man could internalize and simulate a system analogous to the 10 trillion neurons of our brain with on average 7,000 synaptic connections to other neurons, it is not clear that the simulation of all the chemical and physical interactions going within the quadrillions of interconnections will not give rise to emergent phenomena, one of which may be actual understanding. It makes a lot of sense to point out, as Searle does, that there is a significant difference between physical phenomena and the simulation of physical phenomena. A simulated rainstorm does not make you wet, a simulated fire does not burn down anything. Why should we suppose that a simulation of understanding, be it executed by a computer or by another brain, actually understands anything? Because mind may be fundamentally different from other phenomena in that it is not so much the physical constituents that make up the phenomenon but the pattern of the constituents. Patterns don’t get lost when they are simulated. We cannot be sure that it is the patterns that matter, but we cannot be sure that this is not the case either.
Searle seems to be sure that this is not the case when he states that, as long as we simulate only the formal structure of the sequence of neuronal firings at the synapses, we are still missing what matters about the brain, that is, its ability to produce intentional states, since even such a low-level simulation is no more than syntactic manipulation that relates symbols to each other but not to the external world. It is obvious that, if you subscribe to the view that only certain biochemical processes can cause experiental states, there is no way to convince you that other physical arrangements may result in the same experiential states. However, it is important to note that Searle’s claim that “all the computer has is more symbols” is not sufficient to justify this view. The information that is received by our sensory receptors and converted into electrical signals is no less symbolic than the information that is processed by the program of the robot. The information is no more grounded in reality than the signals from the light that hits the camera of the robot.
Therefore, to say that no purely formal model will ever be sufficient for intentionality because what matters about brain operation is not the formal shadow cast by the sequence of synapses but rather the actual properties of the sequences can only justified by an a priori assumption that intentional states can be caused by biological mechanisms exclusively. If you take into account the fact that biology, which follows the rules of physics, is no more semantic than computational models which follow purely syntactical rules and that physical events involving complex, large-scale patterns may result in phenomena that are qualitatively different from their low-level consituents, you don’t have much ground for the claim that robots can’t show understanding just because they are implemented as a computer with the right sort of program.
In 1667, when the chemistry behind fire was still a great mystery, Johann Becher theorized that all flammable materials contain phlogiston, a substance without color, odor, taste, or weight, that is liberated in burning. Similarly, two hundred years later, Lord Kelvin went on record saying that “[life's] power of directing the motions of moving particles, in the demonstrated daily miracle of our human free-will, and in the growth of generation after generation of plants from a single seed, are infinitely different from any possible result of the fortuitous concurrence of atoms… Modern biologists were coming once more to the acceptance of something and that was a vital principle.”
Nowadays we know that combustion requires oxygen, a substance that was well known in Becher’s time, and that life is not caused by a mystical essence that makes inanimate substances animate but by cell processes that can be explained without any physics that were not known in Kelvin’s time. We cannot exclude that Searle’s suggestion that understanding can only be caused by a hitherto unknown mechanism in the brain’s biochemistry is true, but it nonetheless strikes me as improbable and may well be a repetition of the common error of making up new laws of physics instead of trying to see where a phenomenon fits into the current framework of the natural sciences.
[1] The entity may not necessarily be physical, but the occurrence of a mental state implies that something experiences the state.
[2] This implies that either animals have some degree of consciousness or that animals are no more than machines without actual intentionality. Cf. Jean-Paul Sartre, Being and Nothingness.
[3] Which, to our knowledge, could be computable.
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I completely agree with everything you have said, yet want to make a point which seems to me to be absolutely crucial for the understanding of the subject matter and I strongly urge everyone interested in the topic to consider it.
Before that let me point out that it seems that all philosophical debate can not step beyond a point, and most of the time circles around issues it simply can not resolve. The reason for that is actually very simple, namely as long as we use natural language as the language for our discourse we struggle for clarity. Secondly the notion of an essence of something will usually prevent understanding and many people with no knowledge of the history of philosophy fail to clarify the topic. One can easily find out if somebody is such an naive essentialists, e.g. if he says: ‘X is hard to define’, with X being something like intelligence, life or conciousness. Every concpept is hard to define percisely for the reason of it’s use.
Now, let me come to the main argument of Searle which runs in absolute parallel to the foundation of Computer Science after Turing. The essence is the mechanical rule. To emphasise the argument Searle uses additional words, such as ‘just’, ‘pure’, ‘syntactical’. And of course the chinese room thought experiment is only a conundrum, only a koan if I might say in the tradition of Hofstadter, a paradox.
The crucial thing I want to say is that a the model of computation after Turing makes a very similar assumption, namely that there are atomic rules of computation. And of course his work has led to tremendous progress in computer science, after Shannon’s theory of information showed how one can create perfect information out of imperfect physical systems. A discovery yet to be spelled out is the problems that arise in Artificial Intelligence even today after 50 years of work in connection with the assumption of an atomistic mechanical rule.
143 123=266. This computation takes only a second, but which steps are really necessary for it? This question is very hard to answer, because if I want to know in all detail how my brain produced the output I have to go all the way from perception to cognition, from a brain to neurons, etc. If I type in 143 123 in my calculator the complexity of the operation is not as high but still stagering. For me the so called mind body problem should be considered as Popper has put it. There seem to be different kinds of worlds. He called it World-1 (the physical), World-2 (the concious) and World-3 (the ideal). The seperation of the world into the actual and the ideal goes back to Platon. I think today we have at least some intuition where difficulties come from. They come from the scope of observation.
So how should one understand atomic rules? In reality everthing is physically grounded. I can’t do something which doesn’t obey the laws of physics, whatever in detail they might be (one can never be to sure, e.g. a physicist has recently stopped light). So my the operations of my mind, my brain, are subject to the laws of physics and ultimately only be understood within the physical world. Quantum computation suggests, that NP problems are perhaps computable in polynomial time. After all we don’t want to compute NP hard problems, but do what humans to, because – as you correctly pointed out -, we know it is possible, as long as one assumes humans obey the laws of physics and the input-output mapping is reproducable (which Penrose disputes). If we one takes this stance it is very productive to think about the computation of bodies (Morphological computation). There is now much work in embodied AI which shows that the intelligence of many human actions come from a body-coupling, like walking and even social behavior. I am convinced that higher cognitive capacities are to some extent only reproducable from lower capacities (sensory-motor coordinations and morphological computation in general). For this thesis, there probably can not be a formal proof, but also not really falsified. One form of proof is the proof of concept of engineering, that is if we can build it, we can claim to have understood the underlying processes.
Perhaps I can clarify my point with the following.
Searle’s arguments seem to me more than confused, especially here: ‘a simulated rainstorm does not make you wet, a simulated fire does not burn down anything.’ Well, thinking about flying and flying is not the same either, but one can think about walking and walk (if ‘the I’ has the capacity to do so). So if an AI wants to do something it has to have the capacity to do so. If it is physically static it can not move around and gain different perspectives of objects. If it has no sensors it can not feel and if it has no actuators it can not do anything. Most of our human capacity stems exactly from this interaction with the environment. Understanding of music, comes from the physical interaction with an instrument, understanding of objects in general from our early childhood manipulations. Our communication comes from the interaction with other people. A child alone in his room doesn’t learn anyhting, although once an adult it can study by itself. Our capacity to move comes from the structure of the body in its entirety, not just the brain! Our capacity to make tools comes mainly from the structure of our hands, not just the brain and it’s size. There are many other examples which are now being studied and have been studied by biologists. I belive it is crucial to understand that a human is not isolated, it’s capacities develop from the interaction with others, with the environment and the structure of his body, and is not a brain in the vat.
The perfect copy reply…
If one imagines the robot in the example as if it was a perfect functional copy of the human brain plus the human sensory organs, so that the only difference between conceived robot and real human being is the SUBSTANCE it is build up, then I guess Searle would agree that this perfect simulation has in fact “intentional states”. I think, Searle is no substance chauvinist in the sense that he would ascribe intentionality to perfect simulations, if and only if they are made up from the same stuff than brains are mad up. He would rather argue that, if it is possible to build such a android robot, one day, then this robot will be build out of the same substance like brains, just because the brain molecules will turn out to be the most efficient material to build such supercomputers. This is of course and as always no argument against A.I.
I guess Searle would admit, that, in principle it might be possible to produce (not to simulate) with computer chips the very same causal powers than that, possessed by neurons, and even to arrange them in the same functional way as neurons are organized in the brain. But such a fancy robot, which basic hardware components share the exactly same causal powers than neurons do, is no help, because it would be trivially true that such a robot has intentionality (and of course any other property of the brain), since it has the same causal powers as the brain.
In my opinion it is important to specify the used concept of intentionality more detailed, using the notion of “derived” – and “original”-intentionality. What is important, is not solely the fact the computer programs have states that are about something in the world, but that this being about something in the world originates in the computers themselves. In the first sense, any Chess computer can be described as exhibiting intentionality (Dennett’s intentional stance), but only the latter kind is the intentionality in question. How can a machine (how can we?) “produce” intentionality? The problem with Searle is, in my opinion, that he uses a kind of original intentionality that is ways too strong without any reasons. As long as we can explain how brains work, without this strong reading of original-intetionality, that is by only ascribe or impute intentionality to the brain, this should also be enough for computer programs. There is no need to adopt an intentionality-realist point of view.