Cartesian Doubt had wanted to produce a unity of knowledge based upon mathematics. As such, problems were systematically reduced to their fundamental elements, and worked from their simplest rudiments to the most complex. As Goodwin (1999) points out, Descartes is saying “think clearly, logically, and without bias…work systematically...and check your work”. Today we are aware that aim of scientific questioning to find quantifiable, factual and objective evidence in support of any claims made, as well as to search for order (Peterson G, 2002). As Albuquerque J. Deshauer D, and Grof P, (2001) comment “Cartesian thought was to ground all knowledge in certainty, in clear and distinct ideas”. Specifically, he wanted to accept only that which is evidently true; avoid precipitous judgment and prejudice; accept only clear and distinct ideas. Historically, this has had an impact upon the Behaviourist principals which state that behaviourism is a function of its consequences (Everson S, 1997) thus is a proven, undeniable law, very similar to Descartes’ doctrine.
From the systematic reduction of every conceivable thing in our world, even unworldly things such as God, Descartes came to his conclusive thought, that to doubt is to be thinking, and to be thinking is to exist. When the proclamation of, "Cogito ergo sum," was made, Descartes created a chimerical precipice between body and mind. This fictitious boundary was predicated on the notion that the world could be manifested from thoughts, but because one does conceive the outside world, one must therefore exist. In terms of psychology, this argument played a large role in instigating the ‘conscious’ and introspection, to reemerge, as significant. These are illustrated in further psychological works by Freud who theorised on the presence of the ‘ego’ and the ‘id’.
Thus it was that Descartes' efforts to achieve certainty by withholding assent from everything susceptible to doubt instigated a revolution not just in philosophy but in the whole tenor of intellectual life. Descartes’ thought experiments, which mark the beginning of modern psychology and cognitive science, respectively, indicate how important the development of mathematics has been for the constitution of the science of mind.
Cartesian dualism
Relevant to the study of psychology, is Descartes' consideration of the difference between the body and the mind. Descartes saw the body and mind as having different features. The physical body, the res extensa, of a person was seen as an object, based on his definition of an object as something that occupies space, is malleable and has the capacity to move. These same features are not true of the mind or soul, the res cogitans. In fact, the mind, according to Descartes (1646), does not occupy space, it needs “no place and depend[s] on no material thing”; his soul is “entirely distinct from the body,” and “even if there were no body, the soul would not cease to be all that it is.”(Descartes, 1648) That is, when Descartes refers to the mind he refers to its thinking capacity, not the physical entity which is the brain.
Contemporary neuroscientists and cognitive psychologists rightly reject this ontological separation of mind and body stating that it is no longer tenable (Baker M, Kale R, Menken M, 2002). The former maintain that psychological functions can be fully explained by neurology. The latter present a distinct psychological dominion, one whose processes, like those of computer software, are open to scientific investigation. The res cogitans is deceptive no longer. We can map it, scan it, and explain its functions in biological or computational terms. Even with this doctrine however, there is wide debate, as many philosophers have pointed out that, this new canon keeps alive the essential features of Descartes’ philosophy. Particularly, it continues his epistemological severance of inner mind from outside world.
Additionally, Descartes distinguished between humans and animals through language and reason as definitive visible marks of human uniqueness. Peterson (1999) states that this criteria set out by Descartes, is still used in various forms today mainly in the forms of consciousness and self-consciousness with rationality serving as the empirical indicator if their presence, in humans. This is illustrated, through Descartes mechanical model of nature, where he posits the principle of the Animal-Machine, which accordingly does not feel pain when it is vivisected, as it does not have a self-conscious. For Descartes, animals were conscious androids. They saw, heard, and ‘‘emoted’’ without ‘‘knowing’’ that they were so doing. Today, it is evident that it is not only animals which can act in such a manner; many human beings are susceptible to this dogmatic decree, for instance, those with blind sight, or long-distance truck drivers.
Essentially, Descartes comments, ‘‘. . . although the soul is joined to the whole body there is a certain part where it exercises its functions more than all the others’ (Descartes 1643). The rational soul which communicates with the “machine” body through the pineal gland allows humans to go one step further: not only to know but also to ‘‘know that they know.’’ It also provides our reflective certainty of our chosen freedom.
Descartes and reflexes
Although Descartes only used the word ‘reflex’ once to develop his conception of non-human animals as automata, he implies in his works that animal behaviours are non volitional reactions (Bennett, M, 2002). In an attempt to explain the human body, Descartes’ argument centers around a mechanical clock. Today, it would be more appropriate to liken the body to a computer, capable of completing complex functions, as it has so often been termed. Nonetheless, he explains bodily functions and behaviours in a completely mechanistic way. This mechanistic analysis of reflexive behaviour has been looked upon as the beginnings of both stimulus response and behaviorist psychology.
In the Regulae Descartes (1630) attempted to show precisely how a mechanistically conceived world and brain can give rise to perceptual cognition (Kirkeboen 2000). His fatally flawed ideas about the operation of the nervous system have allowed many future psychologists, and neurologists to critique his work and reach a conclusive dialogic model of how the nervous system works. As Kirkeboen (2000) explains however, “Descartes’ reflex model of behaviour was considered the modest beginnings of modern psychology”. Descartes believed that “animal spirits,” gusts of air or flame, originate in ventricles and flow through nerves which he presupposed were hollow, effect involuntary actions such as bodily functions. This idea serves as the origin of what we now know to be reflexive actions. Moreover, Descartes believed sensations do not reveal properties of reality outside of the mind. That is to say, sensations do not inform the mind about extramental things; rather, they enable the soul to assess the function, and meaning of extramental objects.
Descartes and emotions
For Descartes emotions arose from two sources, the intellect and the body (passions of the soul, and passions of the body). The more subtle emotions experienced by the soul, were seen to be superior to those originating in the body, as they are seen to be coarser and often troublesome (Albuquerque, J Deshauer, D Grof P, 2001). In his passions of the soul, Descartes aimed at the explanation and categorization of human emotions. His was the first non-mystical attempt at understanding the normal pathological occurrences that we experience. He described perceptual experiences, in particular six definitive ones from which all others could be derived. These included love, wonder, hate, joy, desire, and sadness.
In terms of psychological contributions, Descartes passions served as one of the earliest forays into psychological issues, as he identifies the enduring methodological challenges to the understanding of emotional problems. He makes a distinction between cognition and emotion which is still with psychological studies today. Most importantly, and of relevance to all psychologists and psychiatrists alike, is the idea that one must constantly tolerate theoretical uncertainty while trying to grapple with aiding suffering individuals (Albuquerque, J Deshauer, D Grof P, 2001).
Conclusion
Conclusively, the modern world is, in a deep sense, a Cartesian world. To welcome and understand the extent of Descartes' continuing presence, one need only consider the triumph of scientific rationality, in terms of methodology and systamatisation and technology. Descartes did not single-handedly devise and formulate these defining features of modernity, the fundamentals of which were developed by an even earlier era. Nevertheless, along with Copernicus, and Galileo, Descartes was one of the key figures in the formulation of the so-called "New Science" that was certain to become a substitute to the reflective model of science inherited from the Greeks.
It is essential to note that many of Descartes psychological ideas are wrong, and fatally flawed, however these ideas are crucial as they provided the opportunity to be proven wrong. That is to say, Descartes has contributed innumerably to the study of psychology, this contribution however is not a matter of correctness of ideas, but rather the occurrence of ideas.
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