Descartes feels that man is far from just a complex machine or animal. In Part Five of his Discourse on Method, he establishes two means by which to identify if a machine is really a rational human being or not. The two means are separate criteria that both strongly portray Descartes’ belief in mind-body dualism. Mind-body dualism is the belief that the mind and the body are two separate and distinct substances. Descartes feels that the mind of man is what sets him apart from being a complex machine or animal. This idea forms the foundation of his two criteria.
The first criterion established is that a machine could not actually use words or other signs in conjunction with each other to declare its thoughts to others. A machine may be programmed to respond to a number of different stimuli such as certain words or physical interactions, but that same machine will never be able to react to any and all possible stimuli. Descartes believes that even the simplest of men can respond to any stimuli while using at least some type of understanding or reason to form a complete statement as a response. A machine, on the other hand, cannot possibly be built to respond to all possible situations with a complete response such as this.
Descartes uses this criterion to distinguish man from other complex animals as well. He states that while even the dullest of men can formulate complete sentences or assertions from words to display their thoughts, the brightest of animals cannot do such a thing. There are a number of animals who have the organs necessary to speak the language of man, but they still lack the mind to understand how to speak with the words man uses. Even in the case of the few animals that actually can physically speak using these necessary organs, such as parrots, they still do not know or understand what they are saying and are simply using mimicry to copy the noises they hear. Descartes points out that even men who are born lacking the necessary organs to speak, whether they are blind or deaf, can still create their own languages to convey their thoughts with reason and understanding such as men without these handicaps can while using spoken language.
Descartes makes the point that the natural movements animals use or unique sounds they make to portray their emotions should not be confused with the complex language system used by man. He believes that these actions do not show true understanding or thought. Instead, Descartes relates the actions of animals to the reactions of a machine to a stimulus, as the animal is just acting through its parts as a machine would. Another misconception Descartes believes some people make is thinking that animals may speak to one another but through a language that cannot be understood by men. He argues that this cannot be true due to the fact that animals have the same organs as man and could just as easily make their language understood by man as it is understood by their fellow animals.
The second criterion to distinguish between man and machine is that no machine can do all of the tasks that humans are able to do. Although a machine may be better than man at performing a specific task, that same machine will still fail in other tasks. The task a machine performs is only possible through the disposition of its organs/parts and not from its own knowledge or mind. If a machine were to be created that could perform all the tasks that man could, it would need a new, separate part for each individual task that man could possibly perform. Descartes believes that man can perform literally any task through his mind, and, therefore, for a machine to be able to perform all the tasks that man can, it would also need to have an infinite amount of parts.
This argument of Descartes’ may also be used to differentiate between man and animal. It is obvious that many animals have much more skill in some of their actions than man has in these same actions, but these same animals also completely lack the ability to do other skills that are deemed simple by man. To Descartes, the fact that certain animals can do certain activities better than man can does not prove that they have any intelligence. It is similar to the clock’s ability to count time better than a human could. This is in spite of the fact that the clock has no intelligence and could in no way do anything a man could do, other than keep time. An animal may be able to run faster than man can, such as the clock can keep time better than man can, but neither has the capability to do something man considers simple such as count the number of hands they have.
Descartes’ philosophic view of mind-body dualism is prevalent throughout his two criteria. He believes that because the body and organs of man are near identical to those of the animals around him, it would be reasonable to believe that man would also act similar to these animals, as in without his deep thought or reason. To Descartes, the fact that the human mind is separate from their physical bodies is what makes them different from these animals. He believes that the mind of man could not just be a physical thing because it could then be recreated such that a machine could be recreated. As noted earlier when discussing the second criterion, no machine could possibly match the human mind due to the impossibility of creating a machine with an infinite amount of parts/organs. A comparison between the organs of man and animals is also a strong example of support for the argument of mind-body dualism. If the mind were simply the combination of the organs in the human body working together, there would be no reason for animals not to possess this same mind, which Descartes has already argued (through his two criteria) could not possibly be true.
I disagree with Descartes’ reasons for thinking why man should not himself as a machine or animal. I find basic flaws in the fundamental ideas behind his two criteria. His first criterion is based on the lack of a formal system of language for animals. He uses this fact to claim that animals, therefore, cannot have reason. In the time since Descartes put together his ideas in the Discourse on Method many scientific gains have been made in this area, and many of the findings from these experiments have come to completely disprove Descartes’ ideas. Animals have shown large capacities to learn, from gorillas knowing over two-thousand symbols in sign language to dogs differentiating between photos of other dogs and photos of different animals. Both of these examples show the animal ability to not only learn, but also to reason. An argument could possibly be made to say that these two signs of intelligence are mere instances of animals using mimicry, such as parrots speaking, but an argument based around this is nothing but speculation. Activities such as these display a more vast knowledge and mental capacity than Descartes previously thought possible.
His second argument was based solely on the fact that while some animals can be better at one thing than man, they cannot possibly do all that man can do. I find this argument faulty in that someone could also compare one man to another. While one man can do some things the other can’t, it does not justify one as having a mind and the other not. I believe that no living thing, neither man nor animal, should be compared to a machine, as opposed to Descartes’ argument that just man should not be able to be compared. This is because I believe that both animals and man both have the ability to reason and react to all stimuli while machines cannot possibly be given the ability to do either of these based on Descartes’ “infinite parts” argument.