In the Sixth Meditation, Descartes makes a point that there is a distinction between mind and body. It is in Meditation Two when Descartes believes he has shown the mind to be better known than the body. In Meditation Six, however, he goes on to claim that, as he knows his mind and knows clearly and distinctly that its essence consists purely of thought. Also, that bodies’ essences consist purely of extension, and that he can conceive of his mind and body as existing separately. By the power of God, anything that can be clearly and distinctly conceived of as existing separately from something else can be created as existing separately. However, Descartes claims that the mind and body have been created separated without good reason. This point is not shown clearly, and further, although I can conceive of my own mind existing independently of my body, it does not necessarily exist as so.
On page 56, when Descartes talks about how sailors are related to ships and why the mind body union is different, he is vague on the metaphorical analogy. To try to get his point across, dualism is used. Descartes is talking about something called interactionist substance dualism. He is stating that the mind and body causally interact with one another. This can be summed up to say that as easily as the mind can cause changes in the body, the body can also cause changes in the mind. Therefore the mind and body must be intimately united. An example of this is having the intuition to raise your hand. Your mind thinks about raising your hand and your body automatically does so. Contrary to this, if you step on a pin, your body tells your brain it has stepped on something sharp, thus causing pain, and your brain tells you that you have pain and to get off. In order to follow this, you must have a strong belief in the existence of God. For only God has the means necessary to make me certain that the two things exist separately of each other. This is because God is a perfect entity, and is capable of countless things whose true causes are beyond my knowledge.
To try to explain Dualism through God, we must talk about corporeal bodies and our knowledge of them. Regarding the nature of corporeal bodies and what is known about them and given Descartes premises, the conclusions he draws in Meditation Six are generally the correct ones. He again invokes the causal to argue that the ideas of bodies we have within our minds must be caused by something with at least as much formal reality as the ideas have objective reality. By saying this he means that a formal reality is expressed as an infinite substance, finite substance, or finite mode. And by objective, we are talking about ideas or representations that we have of these finite substances, infinite substances, and finite modes. One could theoretically be producing these ideas, but Descartes dismisses this possibility for two reasons; first, that the idea of corporeality does not presuppose thought and second, that our will seems to have no effect on what we perceive or don’t perceive. He believes this because the scope of the will is wider than that of the intellect. Therefore, turning aside from making any judgment where one is at all questioning causes the correct behavior and avoids any error.
From Descartes point of view, he thinks that it makes sense to talk of degrees of reality to qualify the above assumptions, and he sometimes equates this with talk of degrees of perfection. Thus, he brings God back into the picture. The ideas, then, could come from only God, or from another being superior to humans but inferior to God. But this, too, is impossible, argues Descartes, as if it were the case that God produces the ideas of bodies in humans, then the very strong inclination we have towards believing that the idea-producing bodies resemble the ideas we have would be false and thus God would be allowing us to be deceived which is not permissible. The same would apply if any other being were producing these ideas. Thus, concludes Descartes, it is most likely that our ideas of corporeal bodies are actually caused by bodies resembling those ideas. Descartes puts this idea into his own words, which can be more easily understood using the causal argument for the existence of God. The causal argument says that if x is identical to y then it is necessarily identical to it. From this argument, the “Sixth Meditation” follows that if it is possible that x and y have different properties then they are distinct. In this instance, if I can clearly and distinctly conceive of my mind and body as existing separately, then they are distinct. The argument is too technical and involved to explore here in much depth. However, it is possible to clearly and distinctly conceive of Two Face, the villain from Batman, as having two sides. These two sides of him are distinct and yet they are identical.
We cannot be certain, however, as we cannot claim to have clear and distinct notions of everything we perceive, for our senses deceive us. It is possible, however, to claim certainty with regard to those properties of bodies which we do know with clarity and distinction; namely, size, figure (shape), position, motion, substance, duration and number. Obviously we cannot claim that we know these properties for specific bodies with clarity and distinction, but we can conclude what Descartes means.He is saying that we can be sure that these primary qualities exist in bodies in the same way that they do in our ideas of bodies. This cannot be claimed for qualities such as heat, color, taste and smell, of which our ideas are so confused and vague that we must always reserve judgment. This can be seen in the wax example.
Do you think that Descartes qualifies to your satisfaction that the mind and body are separate from each other? Only halfway; too many things are left up in the air, and the language is not quite clear. The mind and body can each exist separately and independently of one another. But they also need one another to work properly. This relationship is why the mind and body argument was shown with the sailor and ship scenario. By claiming that the mind and body were similarly related to each other as the sailor and the ship, Descartes was giving the average but intuitive reader something to ponder about while trying to make up his or her own mind about the relation between mind and body. From my point of view, however, Descartes needs further argument to prove that the mind and the body are distinct.