Obviously this isn’t really a review, I don’t think that reviewing historically significant works of philosophy is something that can really be done outside of a proper academic environment, much less by someone like me, reading these works out of curiosity. This is why, what follows are just thoughts and impressions I got reading Descartes.
Descartes influence on philosophy can’t be understated and reading his works it is easy to see why: Discourse presents a very personal project, honest and modest convictions and objectives, while Meditations showcase a very clear reasoning process. It’s also very easy to empathise with his condition; I think Descartes was a scientist at heart, interested in studying the physical world around him and developing tools for understanding it, but met a hampering philosophical system, a legacy of thomistic scholasticism gone wild, pushed by people unsuited for philosophical or scientific arguments. In this environment it is easy to see why Descartes was interested in starting tabula rasa, removing all the baggage and building his own.
Descartes builds his system up from reason. Disregarding any perception, as any perception might be deceived, he creates the famous minimum positive statement: “I think therefore I am”. It’s interesting that he is not concerned about questions related to his ability to reason in the absence of perceptions (or in the presence of false perceptions). Can reasoning even take place if we separate the thinker from the world? Without answering this question, can we claim that any question can be answered without the influence of a potentially illusory world? These questions are answered when considering that he builds his model of thought on the scholastic one, which takes a clear separation between thinking and perceiving, but Descartes project was fundamentally moving away from that foundation.
In fact this is a recurring problem from what I can tell. Descartes is driven to integrate in his philosophical system a lot of necessary conclusions or premises from the system he is trying to replace. This is important, because these premises would constitute the basis on which to make further useful statements about the world, having a foundation and the concepts necessary to do those, without the overburdened inheritance which would stifle philosophical or scientific investigation. These necessary concepts are many, but the main ones are the existence of God and then the accuracy of perceptions/thoughts about the world. But in rushing to obtain these grounding concepts he uses sloppy or unconvincing arguments: he reasons as someone who is aware of the truthfulness of the statements he is making (because they are necessary in his project and because they have been proved sufficiently in other philosophical systems) so is not really concerned with studying potential counter-arguments, or various alternative paths his system might take (which in a simple system as his at this point, are many) only in so far as they might disambiguate what he intends to express.
Because of these “rushed” proofs, some concepts are altered by their new significance, properties or simply role they play in his project. The most central concept that Descartes uses and fundamentally changes from his predecessor is God. In his philosophy, God is the linchpin used to go from making a priori true statements to true statements about the physical environment. But Descartes’ God is not Aquinas’ God. Scholastic tradition anchored the concept of God in the physical world, so the presence and various other essential characteristics of God would then be used to make further statements about the world. Descartes reaches God by observing his own essential, fragmented qualities and seeks to determine their perfect cause. Since this cause is not found in the world he concludes that it must come from God. But hasn’t he done a leap here? He considers the virtues that are within him as finding their perfection in God, but a virtue-based approach is not warranted at this point, following his strict reasoning. Descartes uses here a scholastic approach (taking virtues as essential, and non-virtues as flawed/partial forms of those virtues), an approach that is formed and argued exactly by performing deductions from God. It’s like Descartes flips a logic chain, but in doing so loses coherence.
I think there are also some things to say about what further implications Descartes approach to God has. Because God is no longer understood as related to nature, essential arguments related to God’s existence can’t be applied:arguments from contingency and from causation are no longer admitted under Descartes method (though conclusions or concepts obtained by reasoning in that way are still used by him). This is because those arguments rely on making observations and reasoning about a world that is uncertain , extrinsic to the thinker, so outside Descartes philosophical “game”. This is important, because in this way, we have lost a perspective that fundamentally separates God from the creation and simply anchored Him in our qualities. Why the knowledge of the possibility of the perfection of these qualities can’t be determined or at least hinted by the world we live in is not seriously discussed. I think this discussion is useful to have, since it alone separates (or even justifies) the concept of God at this point, otherwise we might simply refer to God as the world itself and do away with the need of an idea of God altogether.
As I mentioned, Descartes then uses God to justify having some belief in the authenticity of the world, by using the argument “God is fundamentally good, God would not deceive me, therefore I am not deceived and am experiencing an authentic reality”. But what is this good that God should possess or contain? Couldn’t Descartes be deceived exactly by that, assuming what is good and what isn’t? Again, this is a different approach from his predecessors, Descartes judges the virtues of God with respect to what he is experiencing as good and bad. This is a consequence of centering his philosophy on the conclusions and models of his own reason, starting from a skeptical approach of the world and therefore unable to define virtues as aspects of God’s relationship to the world. In Descartes approach, he is very constrained in the amount of factors that he can investigate to obtain his conclusions and it is very easy to make the argument that though this will generate a very simple model, it will also be unable to explain or to reason about very many things, so very many things will hamper it.
What I really appreciated about Descartes, however, was his immense clarity and how inspiring reading him felt. Because he introduces his system as profoundly personal and gradually builds it up, I felt part of that construction, building my own thoughts on the matter as I went along. This quality of his work allowed philosophy to avoid the stagnation that was happening and for something new and better suited for physical discoveries to develop. Descartes left both a very clear system in place, so easy to understand as well as criticize and then further improve on, as well as made sufficiently vague claims to invite copious criticism and development to take place, placing him at an essential point in the history of philosophy.