The 17th Century Rationalists and how their influence can be seen today This essay sets out to discuss a number of views of the relationship between mind and body

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The 17th Century Rationalists and how their influence can be seen today

This essay sets out to discuss a number of views of the relationship between mind and body.   Can our minds and our physical brain be two separate entities that behave totally independent of each other?   Are they separate but perhaps inter-related and running parallel to each other with our inner and personal mental events being elicited by events in the brain?  Or is the mind no more than a side effect of our physical brain process meaning that qualia or our sense-data and emotions don’t really exist and that these processes that lead to our behaviours are simply physical ones that are intrinsically part of us as human beings being derived from the universe as a whole?

I will discuss the views and ideas of the Rationalist philosophers Descartes, Spinoza and Leibniz and the extent to which their ideal help to illuminate contemporary discussion such as the Turing Test and the Matrix.   Rationalists believe that knowledge is gained by using a priori reasoning as opopsed to a posteriori reasoning, a distinction among judgements, propostions, concepts, ideas, arguments or kinds of knowledge.     A posteriori presupposes sensory experience while a priori is independent of it.   An a posteriori propostion argument relies on specific information which is derived from our sense perceptions while an a priori proposition is determined by reasoning alone.   For example 1 + 1 = 2 is known as an a priori deduction while a statement such as the Menai Bridge links Caernarfon and Anglesey is posteriori propostion.

I will also discuss Descartes’ question of our existence and how important it still is to philosophers and scientists who study Artificial and Computer Intelligence, looking, for instance, at the Turing Test as an example of the way in which his ideas have relevance to the foundations of academic debates about AI.   I will also discuss the recent trilogy of films  the  Matrix, which is an example of the way in which his ideas are relevant to discussion of AI in popular culture.

What is the relationship between events in the brain and our private, inner, subjective experiences of our inner mental being?   Not assuming that consciousness and mind are one and the same, consciousness could simply be a facet of the mind, but the issue here is whether consciousness exists.

Before the 17th Century’s Scientific Revolution, little was known about how our brains worked and the distinction between mental and physical phenomenon was vague, but it was understood that there was a difference between our private thoughts and experiences and the more public outside world in which we all live our day-to-day lives.   Perception was not understood at this time,  making boundaries between our inner selves and the world rather fuzzy and unclear.   It was believed that noise, colours, and sights, the making of our phenomenal world, are objective phenomenon belonging to the public world.

Descartes’ program in the Meditations was to place the structure of our knowledge onto a secure foundation.   He set out to review his beliefs, many being contrary, some more or less justified than others.  He even argued that, while propositions of mathematics, seem certain, they sometimes turned out to be false.  He decided to put his jumble of beliefs in order.    He needed to begin with the most certain and fail-safe, but how did he decide on a starting point.

He noted that many of his beliefs derived from his senses and perception and that senses could be misleading.    For example a stick looks bent when partly submerged in water when in fact it remains the same.    The size of the sun and the moon can be perceived to be much smaller than they are in actual fact.   We can also hallucinate and believe that something exists when in fact it doesn’t.   He decided never to trust anything that had deceived him once and thus decided to reject sensual information as being infallible.

We may think that our senses are deceiving on occasions, Descartes could have been sure that he was in his study, that he was a Frenchman who was interested in philosophy etc.   But he recognised that there was no clear and definite way of differentiating between a world of dreams and reality.  The same applies to us.  How can we be absolutely sure that the life we live is not part of a dream?   There is no failsafe way that we can distinguish between dreaming and being awake.    Dreams can often be so vivid that we are convinced they happen.  We sometimes recall events and remain convinced that we did experience them but later “realise” that we must have been dreaming when doubts are raised or we find proof that these events never actually occurred.

Decsartes believed the human mind that was created by God was able to be certain of material things when conceiving them mathematically. God, according to Descartes had the power to create whatever we perceived and he though God too good and kind to allow the human mind to mistake what it conceived matter mathematically.   But even though the method of mathematics is sound it is always possible to make mistakes in our calculations.

He therefore concluded that there was no real way to know anything.    However this was not his intention – he wanted to find certainty.

Descartes decided that instead of examining each belief individually, he would examine each against a method of doubt.   The idea was to question the source of each of his beliefs and to ask whether the source was infallible.   If he failed to prove its infallibility, he was then sure of the unreliability of that source for a foundation of knowledge.

Descartes claimed that his method imitated that of the architect.  When an architect wants to build a house which is stable on a piece of ground where the topsoil is sandy but over rock, he removes the sand and anything else that may be mixed up with the sand by digging trenches.   He similarly began by removing all doubt and throwing it away like the architect did with the sand to ensure that the foundations are stable.  This is called foundationalism where every doubt is cast aside to return to a safe and sure foundation.  The method he used is called the  method of doubt.    Some wonder how we can wonder we are not dreaming.  Some agree that you cannot feel pain in a dream, but others say they have.  The argument that dreams are not related to memory is strong because most people do not remember their dreams.  Descartes explains that in a dream you can feel as if you are using all your senses, but they seem to become more vague than when awake.  Descartes struggles with the dream issue until he comes upon his conclusion.  

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So Descartes rejected all perceptual knowledge and turned to what he believed on account of his own internal reflections.     But surely he knew that 2 + 3  = 5, that a mother is older than her daughter, a triangle has three sides?  But Descartes said that he could have been the subject of a huge deception.  Then he imagined another scenario whereby he might have been deceived by a malignant and powerful being into believing anything that he so chose by being capable of manipulating his thoughts, as God could if he weren’t supremely good.  

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