Rene Descartes: Meditations on First Philosophy Rene Descartes

Before publishing the Meditations, Descartes submitted his manuscript to many philosophers, theologians and a logician, encouraging them to criticize the work. He explained this purpose in a letter to a friend: "I will be very glad if people put to me many objections, the strongest they can find, for I hope that the truth will stand out all the better."[16] The objections which he gathered, and his own replies (many of which are quite extensive), were included in the first publication of the Meditations.

The seven objectors were, in order (of the sets as they were published):

1. The Dutch theologian Johannes Caterus (Johan de Kater).
2. Various "theologians and philosophers" gathered by Descartes' friend and principal correspondent, Friar Marin Mersenne.
3. The English philosopher Thomas Hobbes.
4. The theologian and logician Antoine Arnauld.
5. The philosopher Pierre Gassendi — Descartes wrote that this set of objections could be easily dismissed.[17]
6. Another miscellany gathered by Mersenne.
7. The Jesuit Pierre Bourdin.

Some of the most powerful objections include the following:

Objections to proof(s) of God’s existence:

1. We have no (clear) idea of an infinite Being (1st, 2nd, and 5th objections).
2. From the fact that I can think of a perfect being, it does not follow that the perfect being exists (1st, 2nd, and 5th).
3. We could get the idea of God without God's causing the idea (2nd, 3rd).
4. Nothing can cause itself to exist (4th), so God cannot cause himself to exist unless God is composed of some essence that in and of itself has the property of timelessness.

Objections to the epistemology:

1. How can we be sure that what we think is a clear and distinct perception really is clear and distinct (3rd, 5th)?
2. Circle objection 1: if we are not certain that judgments based on clear and distinct ideas are true before we prove God’s existence, then we cannot be certain that we are a thinking thing (2nd). Circle objection 2: if we are not certain that clear and distinct ideas are true before we prove God's existence, then we cannot be certain that God exists, since we use clear and distinct ideas to prove God's existence (4th).
3. Contrary to what Descartes argues, we are certain that bodies exist/that perception coincides with reality (5th, 6th), but we are not certain that the bodies of our perception are actual bodies in an existent external world.

Objections to philosophy of mind:

1. Ideas are always imagistic (3rd), so we have no idea of thinking substance (non-image idea).
2. We cannot conclude that the mind (thinking thing) is not also a corporeal thing, unless we know that we know everything about the mind. But we do not know that we know everything about the mind. So we do not know that the mind is not corporeal. (2nd, 4th, 5th, 7th).

Elisabeth of Bohemia also corresponded with Descartes on the Meditations.[18] She objected both to his description of the union between mind and body, and that virtue and moral truths seem to need to be grasped by something other than the intellect (despite Descartes' assertion that all truths must be grasped intellectually).[19]

Descartes' philosophy of solipsism involves the assumption that a given individual will know their own mind best. However, the establishment of behaviorism revealed introspection to be a problematic method.[6] Developments in psychology, based on studies focusing on the relationship between the mind and brain make it difficult to accept Descartes' take that the mind can exist without the body. Further, empirical and philosophical work has shown that the mind, or consciousness, develops as a result of social, linguistic, and cultural influence.[6]