Doubt Concerning All Things

Why did Descartes doubt everything?

How did he lay the solid foundations of the sciences. How did he free himself from all doubts?

Descartes cautiously attempted:

1. to put aside all prejudice,
2. to discover the foundations on which everything should be built,
3. to uncover the cause of error,
4. to understand everything clearly and distinctly.

To achieve his first, second, and third aims, he doubted everything, not like a Skeptic whose sole aim is to doubt, but to free his mind from all prejudice.

This was to discover the firm and unshakable foundations of the sciences.

The true principles of the sciences should be so clear and certain that they need no proof.

To achieve his fourth and final aim, Descartes’ chief rule was to:

• enumerate the simple ideas out of which all others are compounded and
• scrutinize each one separately.

When he perceived simple ideas clearly and distinctly, he could understand with the same clarity and distinctness all the other ideas compounded from those simple ideas.

How did Descartes doubt everything? How did he discover the true principles of the sciences?

Doubt Concerning All Things

First, he reviewed all those things he had gathered from his senses- the sky, the earth, and the like, and even his own body.

All of these he had hitherto regarded as belonging to reality.

He doubted their certainty because he found that the senses occasionally deceived him.

In dreams, he had often been convinced that many things truly existed externally to himself, discovering afterward that he had been deluded.

Finally there was the fact that he had heard others, even when awake, declare that they felt pain in limbs they had lost long before.

Therefore, he was able to doubt, not without reason, even the existence of his own body.

From all these considerations he could truly conclude that the senses are not a very strong foundation on which to build all science, for they can be called into doubt; certainty depends on other principles of which we can be more sure.

Continuing his enquiry, in the second place he turned to the consideration of all universals, such as corporeal nature in general, its extension, likewise its figure, quantity, etc., and also all mathematical truths.

Although these seemed to him more certain than any of the things he had gathered from his senses, yet he discovered a reason for doubting them.lo For others had erred even concerning these.

There was a particularly strong reason, an ancient belief, fixed in his mind, that there was an all-powerful God who had created him as he was, and so may have caused him to be deceived even regarding those things that seemed very clear to him.

This is how he called everything into doubt.

In order to discover the true principles of the sciences, he proceeded to enquire whether he had doubted everything that he thought of.

Thus he might find out whether there was not perchance still something left that he had not yet doubted.

If in the course of doubting he finds something that could not be doubted, then he rightly considered that this must be the foundation on which he could build all his knowledge.

Although he had already doubted everything yet there was still something left to be examined – himself.

Examining this carefully, he realized that he could not doubt it for any of the foregoing reasons. For whether he is dreaming or awake as he thinks, nevertheless he thinks, and is. 13

And although others, or even he himself, had erred with regard to other matters; nevertheless, because they were erring, they were.

He could imagine no author of his being so cunning as to deceive him on that score; for it must be granted that he himself exists as long as it is supposed that he is being deceived.

In short, whatever other reason for doubting be devised, there could be adduced none of such a kind as not at the same time to make him most certain of his existence. Indeed, the more reasons are adduced for doubting, the more arguments are simultaneously adduced to convince him of his own existence.

So, in whatever direction he turns in order to doubt, he is nevertheless compelled to utter these words: “I doubt, I think, therefore I am.“14

Thus, in laying bare this truth, at the same time he also discovered the foundation of all the sciences, and also the measure and rule for all other truths-that whatever is perceived as clearly and distinctly as this, is true. l 5

There can be no other foundation for the sciences than this.

Everything else can easily doubted. But this cannot be doubted.

However, “I doubt, I think, therefore I am,” is not a syllogism with the major premise omitted.

• If it were a syllogism, the premises should be clearer and better known than the conclusion.

Therefore ‘I am’, and so ‘I am’ would not be the prime basis of all knowledge.

Furthermore, it would not be a certain conclusion. This is because its truth would depend on universal premises which Descartes had already doubted.

So ‘I think, therefore I am’ is a Single independent proposition, equivalent to the following: ‘I am, while thinking’.

To avoid confusion, we must next know what we are. When this has been clearly understood, we shall not confuse our essence with others.

Descartes remembers all thoughts that he had about himself:

• his soul is something tenuous like the wind, fire, or the ether, infused among the denser parts of his body
• his body is better known to him than his soul
• he perceives the former more clearly and distinctly.

He realizes that all of this is inconsistent with what he has so far understood.

He was able to doubt his body, but not his own essence insofar as he was thinking.

Furthermore, he perceived the bodily things neither clearly nor distinctly. And so, in accordance with his method, he should reject them as false.

He went on to ask what was his essence that he could not doubt.

This had compelled him to conclude his own existence.

His essence included the following:

• that he wanted to take precautions against being deceived,
• that he wanted to understand many things,
• that he doubted everything that he could not understand,
• that up to this point he affirmed one thing only and everything else he denied and rejected as false,
• that he imagined many things even against his will,
• that he was conscious of many things as proceeding from his senses.

He could infer his existence with equal certainty from each of these points.

All these things can be conceived under the same attribute. It follows that all these things are true and pertain to his nature.

So whenever he said, “I think,” all the following modes of thinking were understood:

• doubting
• understanding
• affirming
• denying
• willing
• non-willing
• imagining
• sensing

Here it is important to note the following points, important to the distinction between mind and body:

1. These modes of thinking are clearly and distinctly understood independently of other matters that are still in doubt.
2. The clear and distinct conception we have of them would be rendered obscure and confused if we were to intermingle with them any of the matters of which we are still in doubt.