Rene Descartes, the French 17th century philosopher, had a huge impact on the field of Epistemology. His Meditations on First Philosophy is required reading for anyone who wishes to understand the nature of knowledge.
In recent times, a number of films have posed us questions about the nature of knowledge. The Matrix placed us in a computer generated virtual reality, and asked us if we could tell the difference between “the real world and the dream world”, to paraphrase Morpheus. Inception, the impressive 2010 heist film, also asked the same kind of question: can we know our experiences actually reflect external reality and that we are not merely dreaming?
These questions are not new for philosophers; similar thought experiments, no doubt, go all the way back to Ancient Greece. However, Descartes brought these questions to the forefront of the philosophical thinking of his day.
Aristotle, if you recall in his Posterior Analytics, claimed that the starting-points of knowledge are sense-perception, memory and the ability to gain knowledge of the universals. These starting points are known by “intuition” and not demonstration (a logical argument). Ask Aristotle how we could sure we were not dreaming, and he would (probably) say that it is by intuition that we know that we perceive the real world. But Descartes’ answer is very different.
In Meditations* part one Descartes starts of with some observations about his Philosophical education:
“I first became aware that I had accepted, even from my youth, many false opinions for true, and that consequently what I afterward based on such principles was highly doubtful”
Descartes observes that many of the opinions he once had he now knows are not true, and, moreover, the basic principles which these opinions were based on are doubtful. So he resolves to “demolish everything completely and start again” and to “at length apply myself earnestly and freely to the general overthrow of all my former opinions”.
At this point, Descartes explains his methodology: ” it will not be necessary for me to show that the whole of these are false”, or in other words, Descartes doesn’t intend to prove that all his opinions are not true. Instead, he deems it necessary to “withhold belief from what is not entirely certain and indubitable”. Or in other words, If there is any reason to doubt a belief than Descartes will not affirm it.
But because any one person holds to numerous beliefs it would be impossible to doubt them all. Instead, Descartes goes for the very foundations of these beliefs. First he doubts the senses and all beliefs derived from them because they have sometimes been unreliable. In Descartes own words:
“All that I have, up to this moment, accepted as possessed of the highest truth and certainty, I received either from or through the senses. I observed, however, that these sometimes misled us; and it is the part of prudence not to place absolute confidence in that by which we have even once been deceived.”
But what about seemingly obvious beliefs such as ” I am in this place, seated by the fire, clothed in a winter dressing gown, that I hold in my hands this piece of paper”? To doubt these type of beliefs Descartes recalls that he has such experiences in his dreams: “How often have I dreamt that I was in these familiar circumstances, that I was dressed, and occupied this place by the fire, when I was lying undressed in bed?”
What do we know then?
Descartes suggests we might have mathematical knowledge such as two plus three equals five because this appears to be true whether we are dreaming or not. But perhaps God is making me go wrong every time I try to answer a sum, says Descartes. After all, he continues, God allows us to be deceived sometimes, so why not all the time? He writes:
“…perhaps Deity has not been willing that I should be thus deceived, for he is said to be supremely good. If, however, it were repugnant to the goodness of Deity to have created me subject to constant deception, it would seem likewise to be contrary to his goodness to allow me to be occasionally deceived; and yet it is clear that this is permitted.”
What is there was no God? Then we are in a no better situation, says Descartes. As then, “I reach the state in which I exist, whether by fate, or chance, or by an endless series of antecedents and consequents, or by any other means, it is clear (since to be deceived and to err is a certain defect ) that the probability of my being so imperfect as to be the constant victim of deception“.
But all these doubts are not enough for Descartes. For he can not get rid of “those old and customary opinions perpetually recur– long and familiar usage giving them the right of occupying my mind, even almost against my will”. Try as he might, he cannot make himself doubt everything. So to counter balance “the distorting influence of habit”, he goes on the offensive:
“I will suppose, then, not that Deity, who is sovereignly good and the fountain of truth, but that some malignant demon, who is at once exceedingly potent and deceitful, has employed all his artifice to deceive me.”
And Descartes ends part one with the determination to mediate on this supposition in order not to believe anything false at all. It should be noted that Descartes does not actually believe that a demon exists, instead he continually thinks about the possibility to counter act his so-called habitual opinions. That is how I interpret the point of Descartes’ demon.
And so ends this fully packed post. Find out how Descartes tries to escape from his method of systematic doubting next time.
Should we doubt all our beliefs? What do you think about Descartes method?
*John Cotteringham, who specialises in the study of Descartes work, has a translation which is much more readable, but not freely available online. He also provides extracts from Descartes work in his Anthology of Western Philosophy, which has been a helpful study aid.