A Critical Appraisement

René Descartes (1596-1650) was a French philosopher and mathematician who was disturbed at a young age by the absence in Philosophy of undisputable truths and of a method by which to arrive at them. Cartesian Scepticism (or systematic doubt) is a process of uncovering indisputable truth. This method requires that all beliefs that can conceivably be doubted be considered ‘patently false’[1]; to this end, Descartes made use of three arguments to test his beliefs, namely the Dreaming Argument, the Madman Argument and the Evil Genius Argument. He found himself in a state of distress after eliminating not only the empirical knowledge that he knew by experience to be unreliable but also his cherished mathematical knowledge of pure reason because, Descartes reasons, it is conceivable that an evil genius – as cunning as he is wicked – has put all his energies into deceiving Descartes. In his second meditation, Descartes develops an argument that a thinker can use the Cogito Method to know beyond doubt his own existence. In addition, Descartes attempted to justify both rationally derived knowledge and empirical knowledge through use of the Ontological Argument.

By employing this process of systematic doubt, Descartes gave himself a formidable task. Those truths that passed this examination he considered to be foundational truths. The first of these indisputable truths is commonly referred to as the Cogito, and the second is known as the Ontological Argument. The former is an argument claiming that the doubting of one’s own existence constitutes absolute proof of it. The latter proves the existence of a perfect God and uses this to justify empirical knowledge by making the point that a perfectly good God would not allow for a man to be deceived all the time, but would provide him with the necessary faculties to assess the validity of his perceptions. The arguments of deception (evil genius) and lunacy (madman) do not challenge the Cogito because both require the existence of the subject.

The other argument that Descartes proposes is called the Ontological Argument. By which he justified reliance on both a priori (before experience, purely rational) and a posteriori (empirical, perception based) knowledge. In this argument he takes two premises, firstly that existing is the perfection of the property of existence, and secondly that the definition of God is a supremely perfect being (moral, mental, existence et cetera). Following from these two premises, the defined God must necessarily exist. To say otherwise is as illogical as claiming that a triangle has two sides because it is saying God (as defined in the second premise) lacks existence. This argument is not as sound as the Cogito because it must suppose that its own reasoning, simple as it is, is not susceptible to the trickery of the evil genius while it is being thought. Although Descartes did take this position when challenged, it does not stand up to his own challenge of putting such a process beyond all conceivable doubt because it is readily conceivable that one is deceived during the process of reasoning. It follows logically from the premises but the Ontological Argument is not sound by the standards of Cartesian Scepticism. Therefore, Descartes is erroneous to consider the Ontological Argument the foundational truth upon which a belief in the existence of material objects and the reliability of empirical knowledge can be indisputably based.

It has been argued that the Cogito is just as susceptible to the Evil Genius Argument as the Ontological Argument is, but those who argue this have failed to properly examine Descartes’ case. The Latin phrase often associated with the argument is ‘cogito ergo sum’ (I think, therefore I am) and this has led to some confusion. Due to the use of ‘therefore’ many have taken it to be a logical process of reasoning, and have gone on to claim that it does not counter Descartes’ own Evil Genius Argument. Descartes regretted this misconception and so in his Meditations on First Philosophy he rephrased the argument as ‘I am, I exist’ to prevent confusion. The point behind this terminology is to suggest a self evident (id est foundational) truth rather than one derived by logic. The thinker is assured beyond conceivable doubt of his own existence while considering if he exists.

By making use of the Cogito, Descartes proposes that when it is thinking, a mind is aware of itself. If there is an evil genius fooling it about what it is thinking, it must still exist to be deceived. This is a sound argument. Unlike the Ontological Argument, the Cogito does not rely upon the process of reason that the method of systematic doubt must preclude. At first it may appear that the Cogito claims that as a man thinks he can draw the logical (but evil genius susceptible) conclusion that he exists, but this is not what the Cogito stands upon. Instead, the Cogito is proved by the act of thinking itself; by describing it as a reasonable conclusion of thinking, we merely expand the process in order to explain it better. The Cogito is necessarily true every time it is conceived of. Therefore Descartes did solve the problem of his own scepticism because he proved to himself his own existence.

[1] Descartes, [1641] 1993: p. 13

Works Cited

Descartes, R. ([1641] 1993). Meditations on First Philosophy (3 ed.). (D. A. Cress, Trans.) Cambridge: Hackett.