René Descartes (31 March 1596 – 11 February 1650) was a French philosopher, mathematician, and scientist.
Considered one of the fathers of modern western philosophy, much of subsequent Western philosophy is a response to his writings, which are studied closely to this day. One of his fundamental works was Discourse on the Method which we will read on the following pages
What has given René Descartes a unique hold upon the thought of modern times is his making the mind's position of universal doubt the proper starting place in philosophy.
This he does, however, not in the spirit of scepticism, but in the effort to construct a system of truthful knowledge.
As Bacon was dissatisfied with the assumption by the schools of a priori principles that had no ground in experience,
so Descartes, finding himself disposed to question the authority of all that was taught him, conceived the idea of allowing this very doubt to run its full course, and so of finding what ground, if any remained, for a certain knowledge of anything whatever.
Thus doubt as the natural attitude of the mind, instead of being combatted as an enemy to even the highest and surest knowledge, was itself to be forced to yield up its own tribute of knowing.
This it does in bringing the doubter to the first and fundamental admission that in doubting he is thinking and that in order to think he must at least exist.
Therefore, the existence of the thinker, or the fact of thinking, is a fact beyond the possibility of doubt.
Hence the basic maxim of the Cartesian philosophy,
Cogito ergo sum (I think, hence I am).
In developing his philosophic method, Descartes lays down the following rules for his guidance:
1. Never to accept anything as true which I do not clearly know to be such.
2. Divide difficulties into as many parts as possible.
3. Proceed from the simplest and surest knowledges to the more complex, and —
4. Make the connection so complete, and the reviews so general, that nothing shall be overlooked.
“Convinced,” he says, “that I was as open to error as any other, I rejected as false all the reasoning I had hitherto taken as demonstrations; also that thoughts, awake, may be as really experienced as when asleep, therefore all may be delusions;
yet in thinking thus I must be a somewhat; hence Cogito Ergo Sum.
The doubter's thinking proves his existence. I conclude that I am a substance whose existence is in thinking,
and that there is no proof of the certainty of the first maxim to be adopted except that of a vision or consciousness as clear as this that I have of my own existence.”
But in thinking of his own existence, he is immediately convinced of the limitations and imperfections of his mind from the fact of its imperfect knowledge of things causing him to doubt:
hence he is led to infer the existence of a being who is perfect and without limitations; for it is impossible to conceive of imperfection without conceiving at the same time of perfection;
and it is this perfect being alone which can be the cause of all other beings, since it must be the perfect which gives rise to imperfect and finite rather than that the imperfect should be the cause of the perfect.
Hence we derive the idea of the being of God as the perfect being.
But the idea of the perfection of anything involves that of its existence;
hence Descartes concludes by a logic, whose validity has often been challenged, that the perfect being must exist; and hence, he holds, we are assured of the existence of God.
The proof is strengthened also by the reflection that the idea itself of a perfect being could only have come into a finite mind from such a perfect source.
The idea of God in the human mind at once implies the existence of God as the only possible source of this idea; and the idea of God as a perfect being without existence it would be impossible to conceive.
Further, the knowledge now clearly attained of the existence of God shows us that God as perfect must be a beneficent being whose only object toward his creatures must be to enlighten and to bless them.
Therefore, he would not create beings only to deceive them by making them subject necessarily to delusion.
The evidence of the senses, therefore, as to the existence of an objective world which is as real and as certain as this certain world of thought, must be a true evidence.
The external world exists as truly as the internal. But as external, it is utterly without thought and without consciousness.
The created universe is, therefore, under God, who is the one perfect self-existent Substance, dual in its nature, or composed of two subordinate substances utterly discrete in their nature and incapable of any intercommunication:
The one is the world of thought, the other the world of extension. To the one belong our minds, to the other our bodies.
But while there can be no intermingling or community of those substances so absolutely unlike, yet there is in man a minute organ, the pineal gland in the brain,
where the two alone come into such contact that, by a miraculous and constant intervention of deity, the action of the soul is extended into, or made coincident with, that of the body.
This discreteness of the two planes, or degrees of substance, matter and thought, their perfect correspondence and their mutual influence by contiguity and not by continuity or confusion,
forms one of the landmarks of modern philosophy, and is carried later by Swedenborg into a much more perfect development in his doctrine of Discrete Degrees and their Correspondence.
The treatment of the problems of the mutual influx of these two degrees of substance, mind and matter, has been a distinguishing mark of subsequent schools of philosophy, culminating in the theory of parallelism, which is current at the present day.
While Descartes accounts for the parallel action of these two utterly unlike and incommunicable substances by the supposed immediate operation of God upon both on the occasion of either being affected,
his immediate follower Geulinx regards the coincident action of the two substances as divinely foreordained, so that the action of one accompanies that of the other,
like the movements of the hands of two clocks made to run exactly alike, and yet in no way to interfere with one another. This is the theory of “pre-established harmony” applied by Leibnitz to his world of monads.
Malebranche, however, another disciple of Descartes, held that the interaction of the two planes, in nature inexplicable, becomes possible through their hidden unity and harmony in God, in whom is all life and motion.
Swedenborg, opposing with Descartes the doctrine of physical influx, sets forth the doctrine of a perfect “correspondence” of the discrete degrees of being,
such that motions may be imparted by the contact of these degrees without any intermingling of their substance and by virtue of the harmony of their interior form, all exterior and material things being symbols and vessels of interior things.
With Descartes the lower animals and men as to their purely animal nature are perfect machines and form a part of the stupendous mechanism of the world.
Man alone by virtue of his rational soul presides like an engineer in the midst of this vast machinery and governs the conduct of the body by the dictates of wisdom and virtue.
Man's soul, a thinking principle, is composed of will and intellect, and the intellect is composed of partly innate and partly derived ideas. The thoughts of the finite mind must be imperfect, whereas the will partakes of the infinite freedom of God.
The tendency of the human will is therefore to wander beyond that which it clearly sees in its own limited understanding, and hence from the abuse of the finite human thought arise error and sin.
These privations suffered by human thought are however evidences of God's goodness and justice since the universe is more perfect for the multitude and variety of its imperfect parts.
God is in every one of our clear thoughts, and so far as we abide by them in our judgments we are right; so far as in our own free will we transgress or exceed them we are in error and come into unhappiness.
As regards the thought of God it is not the thought itself that effects the existence of God but the necessity of the thing itself determines us to have this thought.
The thought of God being therefore the ground of all the certainty of any knowledge of anything, the truth of all science must depend on the knowledge of a true God.
The soul's immortality is inferred in the 6th “Meditation” from the fact that we have a clear and distinct idea of thought, including sensations and willing, without anything material appertaining to it; hence its existence must be possible independent of the material body.
Such is an outline of Descartes' arguments in proof of the existence of God, and of his method of attaining to true knowledge. They are given in the “Discourse on the Method”.