Whaterver is Doubtful is False

1. To seek truth, it is necessary once in life to doubt all things as far as possible.

We were children once.

• We formed various judgments regarding the objects presented to our senses when our reason was not yet developed.

Numerous prejudices stand in the way of our knowledge of truth.

• We can only get rid of these if we, once in our lifetime, doubt all those things in which we suspect any uncertainty.

2. All that is doubtful should be considered false.

All the things that we are able to doubt should be also considered false.

• In this way, we can discover with greater clearness what has most certainty and is the easiest to know.

3. But we should not use doubt in the conduct of life.

We will use this general doubt only while engaged in the contemplation of truth. During the conduct of life, we frequently must follow opinions merely probable.

Two courses of action may both have doubtful probability.

4. Why we may doubt of sensible things

We can doubt whether the following really exist:

• the things that have fallen to our senses
  • We know that the senses sometimes err.
  • It would be imprudent to trust too much to what has even once deceived us.
• the things which we imagined
  • In our dreams, we imagine many objects that do exist in reality.
  • A person who has adopted a general doubt will not distinguish sleep from the waking state.

5. Why we may also doubt mathematical demonstrations

We will also doubt of the other things we have before held as most certain, even of:

• the demonstrations of mathematics, and
• their principles which we have hitherto deemed self-evident

Men sometimes fall into error in such matters.

They admit as absolutely certain and self evident what to us appeared false.

Was it God’s will to create us so that we are always deceived?

If we an all-powerful God is not the author of our being, then we exist of ourselves or by some other means.

If our author is less powerful, then we have more reason to believe that we are not so perfect and that we are continuously deceived.

6. Our free will helps us avoid error

We are conscious of a freedom. This:

• prevents us from believing something that is not certain
• guards against us being deceived.

7. We cannot doubt of our existence while we doubt.

This is the first knowledge we acquire when we philosophize in order.

We reject everything that we have the smallest doubt.

But we cannot doubt ourselves while we doubt of the truth of these things.

What thinks exists at the very time when it thinks.

Accordingly, the knowledge, I THINK, THEREFORE I AM, is the first and most certain that occurs to one who philosophizes orderly.

8. We hence discover the distinction between:

• the mind and the body, or
• a thinking and corporeal thing.

This is the best mode of discovering:

• the nature of the mind, and
• distinctness of mind from the body.

In this way, while we examine anything, we suppose that only our thought about it exists.

Space, shape, local motion*, etc are attributed to body.

• Through this method, we clearly perceive that none of these pertains to our nature.
• Only our thought about the body alone pertains to our nature.

Consequently, our own notion of our own mind:

• precedes any notion of any corporeal thing
• is more certain than any corporeal thing

We already perceive that we think before we doubt whether a body exists.