On the Knowledge of Mind: Malebranche V. Descartes

Heavily inspired by Descartes, Malebranche examines the human mind in The Search After Truth. Both philosophers acknowledge that the existence of the mind is better known than that of the body; however, Malebranche claims that the body can ultimately be known better than the mind. This is in direct response to Descartes' claim that the mind is better known than the body. After examining Descartes' claims, we will then examine Malebranche's counter-claims and analyze his strongest arguments against Descartes. Finally, possible responses by Descartes accompanied by an examination of the philosophical bases of both writers may help to show that Malebranche does not effectively serve to disprove Descartes' claim.

For Descartes, certainty of knowledge can be obtained by first doubting everything that can be doubted and then assenting only to clear and distinct ideas. The subject of Descartes' Second Meditation is the nature of the human mind and "that it is better known than the body.1" After withdrawing from his body, Descartes exists as a mere thinking thing- one who can doubt, understand, affirm, deny, will, refuse, imagine and sense (AT 7.28). The realization that he is thinking is sufficient for Descartes to prove his existence, at least as a thinking thing. Next, Descartes finds himself full of ideas, each with their own true nature; and subsequently, he finds it significant that all these things belong to him. Thus, through realization of his existence and that he contains ideas, Descartes has arrived at some knowledge of the mind.

In his Principles of Philosophy, Descartes elaborates on the definition of a substance. This definition helps explain arguments of how the body is better known than the mind.

1. Descartes, R. Meditations, Objections, and Replies. Indianapolis: Hackett Publishing, 2006. All future references will refer to standard Adam and Tannery (AT) numbers.

Descartes believes a substance, or independently existing thing, is characterized by its principal attribute. These principal attributes seem to be equivalent to the essence of the substance. In addition to this principal attribute, substances may have also have modes. Relating this definition to our subject, Descartes believes that the essence or principal attribute of the mind is thought and that ideas are modes of mind.

Given that bodies can be perceived only by the intellect and not by the untrustworthy senses, the intellect must be the ultimate faculty. As the essence of mind is understanding, intellect, or thought, Descartes reasons that "nothing can be perceived more easily and more evidently than my own mind" (AT 7.34). The nature of the mind is so manifest to Descartes that he admits that anything learned from the consideration of bodies will also help to make the mind better known. The idea that knowledge of bodies leads to better knowledge of the mind is expanded in the Fifth Replies when Descartes claims a direct correspondence between these types of knowledge (AT 7.360). For every attribute known about bodies, we learn that the mind has the power to know these attributes. According to Descartes' 11th Principle, he reasons that this relationship arises because the natural light shows us that the clearness of our knowledge is in direct proportion with the number of qualities we know about it. He repeats this idea in the Fifth Replies, arguing that given we understand a substance through its attributes, if we know more attributes then more complete is our understanding of its nature. Descartes concludes that it should be sufficient proof that our knowledge of existence and the essence of the mind leads to a clear idea of the mind. If, however, this is insufficient, then the number of attributes we know about the mind is yet more proof