First meditation

What can be called into doubt

Descartes’ synopsis:

In the First Meditation reasons are provided which give us possible grounds for doubt about all things, especially material things, so long as we have no foundations for the sciences other than those which we have had up till now. Although the usefulness of such extensive doubt is not apparent at first sight, its greatest benefit lies infreeing us from all our preconceived opinions, and providing the easiest route by which the mind may be led away from the senses. The eventual result of this doubt is to make it impossible for us to have any further doubts about what we subsequently discovered to be true.


  1. Remove all ideas which are doubtful
  2. Pinpoint deceitful beliefs and be prudent not to trust them
  3. Being awake and being asleep, thedistinctnessof impressions
  4. Only sciences which deal with thesimplest and most general thingsare the ones that could be trusted, at this stage. They are math and geometry.
  5. There must be a God which gave me impressions of a world which actually exists as I perceive it.
  6. It would collide with God’s goodness to be deceived even once.
  7. Suppose nevertheless that God is a fiction: I have arrived in this state of questioning by chance
  8. I am imperfect and I could be deceived all the time, therefore…
  9. I must withhold my assent from these former belief just as carefully as I would form obvious falsehoods
  10. Even if these preconceived opinions are much more likely to be true than to be false, I turn in the opposite direction and I pretendfor a time that these former opinions are utterly false and imaginary
  11. The introduction of the evil demon
  12. Not trusting any belief in order to avoid any influence by the demon

Skepticism as a mean to reach knowledge. What is undoubtable is true, what is doubtable (not completely undoubtable) is false.

Not an answer to every possible question, but proving the minimum elements to explain Physics.

Arguments for doubting

It is prudent never to trust completely those who have deceived on us even once

Not trusting senses

  • Mad people +++
  • The dream +++

(According to Descartes, children are Aristotelian)

Only one narrating person, but, actually, two distinct “Descarteses”: the child Descartes, and the adult, current, Descartes.

It’s impossible for us to doubt about mathematics, but is it possible to imagine something which could discard even Math? The answer is God.

The evil demon is a summary of all the previous arguments


We have to prove the existence of God to later prove his not being deceitful. God guarantees that subjective certainty is an objective certainty, “a bridge”.


  • The idea of the mind
  • The idea of God
  • Idea of the bodies -> extension -> mathematics

It is then not some kind of abstraction but the real essence of the world

Second meditation



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