Philosophical Works · Chapter
Why we may also doubt of mathematical demonstrations explained
Descartes extends his method of doubt to mathematical demonstrations and their self-evident principles, arguing that because an all-powerful God could have created us such that we are always deceived, even in matters we think we know best,
What happens
Descartes extends his method of doubt to mathematical demonstrations and their self-evident principles, arguing that because an all-powerful God could have created us such that we are always deceived, even in matters we think we know best, we cannot trust them absolutely. He further notes that if we suppose a less powerful author of our being, the likelihood of continual deception only increases.
Themes in this chapter
Methodical Doubt
The chapter extends doubt to mathematical demonstrations and self-evident principles, using the hypothesis of a deceiving God.
Skepticism and Certainty
Descartes questions the certainty of even the most secure knowledge, mathematics, by considering the possibility of constant deception.
Characters to notice
Key passages
“We will also doubt of the other things we have before held as most certain, even of the demonstrations of mathematics, and of their principles which we have hitherto deemed self-evident”
We must also call into question everything we previously considered absolutely certain, including mathematical proofs and their supposedly self-evident foundations.
Descartes expands his doubt to the realm of mathematics, the paradigm of certainty.
“because we have learnt that God who created us is all-powerful; for we do not yet know whether perhaps it was his will to create us so that we are always deceived, even in the things we think we know best”
Since we know God is omnipotent, we cannot be sure He did not design us to be perpetually mistaken, even about what we believe we understand most clearly.
The hypothesis of a deceiving God undermines the reliability of even mathematical truths.