I am briefly aware of Descartes' argument that even if an Evil Genius made us believe that the world is real the fact that we can doubt this shows that we are thinking and that through thought we can exist...

However, what if the Evil Genius put the action of doubting into our minds? Can we really say that we exist through doubt if the very doubt is something implanted into us?

Thanks for reading!

  • 2
    Descartes said we exist through thought / thinking, so that even if the 'evil genius' deludes us into believing it's real, it's real anyway. If on the other hand the 'evil genius' deludes us into believing it is not real, then it must be real: we exist. It is not through doubt that we exist, but again through thought and thinking. So, either way we exist through thought, regardless of whether or not we doubt it.
    – Bread
    Commented Feb 10, 2019 at 23:42
  • 3
    Possible duplicate of Descartes' Demon
    – Conifold
    Commented Feb 11, 2019 at 3:36
  • 1
    great point. Doubt is at the.core of Descartes argument for duality of mind and body. And this concept.of doubt being a factor of the mind, destroys his argument.
    – Richard
    Commented Feb 11, 2019 at 10:18

1 Answer 1


Welcome, questionguy765.

Descartes' genium malignum or malin génie is not an 'evil genius' but a 'malignant demon'. Genius doesn't come into it. Also Descartes does not actually psychologically doubt the existence of the external world and the rest. Since he accepts that he can be mistaken about them, he voluntarily suspends epistemological judgement about them. He practises methodological doubt, and puts methodologically 'on hold' any belief which is not invulnerable to error. Complexities aside in Meditation 2, any belief which passes that stringent test is one he can allow into his construction of the foundations of knowledge.

In his Comment, Bread has got to the root of the matter. 'Our minds' plainly exist if the malignant demon has planted doubt or doubts into them : doubt can't be created in a mind that doesn't exist. More broadly, if the demon has caused me to doubt, psychologically or methodologically, then even if I don't know what has caused my doubt (actually the demon), I must exist in order to be caused to doubt.

There is the point, of course, that my belief that even if I am deceived, I must exist else I could not be deceived, might itself be a false belief induced by the demon. I don't know how to deal with that, but it takes us (I think) beyond the limits of your question.

  • thanks for the answer and a great explanation too Commented Feb 12, 2019 at 9:50
  • Thank you, too - comment much appreciated. Best - Geoffrey
    – Geoffrey Thomas
    Commented Feb 12, 2019 at 10:17

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