The Pervasive Presence of the Evil Genius
(Hypothesis) in Descartes' Meditations
© by Dr. Jan Garrett
Last modified February 15, 2004
To my students: If you are planning to write a paper on a topic very close to this one, I urge you not to read beyond step (3) of the numbered argument reconstruction (about 40 lines below) until after you have worked out a fairly definite draft of your own paper based on your own encounter with Descartes, the study questions, the lectures, and your other secondary sources.
Descartes' hypothesis that there is an evil genius, an expremely powerful, malicious spirit, who strives to deceive him represents the most radical phase of his methodological doubt. This hypothesis of the evil demon operates not only in Meditation I and II, where it is introduced and explicitly discussed, but also in the background throughout the remainder of the Meditations. It is truly relaxed only in Meditation VI, after the proofs for the existence of God in Meditations III and V. But even after the strong version of the evil demon hypothesis (SEDH) is relaxed, a weakened form of it lingers in Meditation VI.
Although the strong version of the evil demon hypothesis is introduced at the end of Meditation I, in a sense it reaches back almost to the start of Meditation I and includes the most of the skeptical doubts introduced there, for instance:
the author's calling into question the testimony of his senses or his empirical memory on the basis of one past occasion on which these apparent sources of knowledge have misled him,
the author's doubts based on vivid dreams as to whether he is currently awake as distinct from dreaming,
the author's doubts whether he can ever know whether he awake as distinct from dreaming,
the author's doubts whether he can trust the kind of memories he has of having once moved by clear steps through long deductive proofs from indubitable premises to significant conclusions
the author's doubts about the existence of an external world.
In what follows I have reconstructed the main line of Descartes' overall argument in the Meditations so as to highlight the pervasive role played by the hypothesis of Evil Genius in first its strong, then in its weakened form.
In the notation I have used "MP" stands for methodological premise, "P" for premise, "A" for Assumption (unstated premise), "IC" for intermediate conclusion, and "FC" for final conclusion. (If there are two or more conclusions that do not serve as premises for further conclusions, then there may be multiple final conclusions.)
Descartes' view is that
(1, MP) What is known without doubt and only that counts as knowledge (of the sort he can include in, and near, the foundation of the scientific philosophy he is seeking).
(2, MP) Those and only those (propositional) ideas that are not called into question by his method of radical doubt are known without doubt.
(3, MP) The hypothesis of the evil demon (SEDH), who is extremely powerful and devious and uses every effort to deceive him, is the key to his method of radical doubt.
Dr. Garrett's students: Did you read the note to students?
(4, P) SEDH reaffirms all the skeptical doubts listed above (reflecting the Meditation I).
(5, P) Applied to "whether I exist", however, reflection under SEDH reveals: "I am, I exist" is true every time I utter it or think it in my mind.
(6, IC) This is known without doubt. (2,3,5)
(7, IC) This can be included in, or near, the foundation of the scientific philosophy he is seeking. (1,6)
(8, IC) SEDH reveals that all propositions regarding the existence of bodies and the material world are quite doubtful. (4)
(9, IC) This thing that I am is not clearly known to have physical attributes. (8)
(10, P) Reflection under SEDH reveals that whenever I dream, or perceive, or affirm, or deny, or doubt, or remember, I am thinking in some way.
(11, IC) Reflection under SEDH reveals that I am a thinking thing that can think in a variety of ways. (10)
(12, IC) I know without doubt that I am a thinking thing . . . . (2,3, 11)
(13, IC) That I am a thinking thing . . . can be included in the foundation (1, 12)
(14, IC) Reflection under SEDH reveals that my existence as a thinking thing is more clearly known than my possession of a body. (9, 13)
(15, A) Reflection under SEDH reveals that while I have clear and distinct enough ideas of my own immediate mental activities and of my own ideas merely as ideas, I cannot know the existence of any material thing or the reliability of intellectual memory until SEDH is weakened.
(16, P) Reflection under SEDH reveals that even if bodies do not exist, the persistent feature of any body would be extension.
[Descartes suspects that SEDH can be weakened by a proof that God exists and is not a deceiver.]
(17) (stand-in for many steps) - It is possible to prove that God, who is not a deceiver, exists.
(18, IC) A supremely powerful nondeceiver God would not permit me to be deceived by my clearest and most distinct ideas about the external world and my clearest and most distinct intellectual memories. (17)
(19, IC) SEDH has been been replaced by a weakened EDH: There may still be a powerful evil deceiver but he can only deceive me about the external world insofar as I have only by unclear or indistinct ideas about it. (18)
(20, IC) I may count as knowledge my very clear idea that there is an external world. (19)
(21, FC) I may count as knowledge the testimony of my intellectual memories of carefully performed mathematical proofs. (18)
(22, FC) I may count as knowledge the carefully acquired quantitative descriptions of the external world. (19, 20)
(23, FC) I may count as knowledge the idea that my self or mind is closely associated with a particular physical body, although the self or mind is a thinking thing and the physical body is an extended thing. (11, 16, 19)
(24, P) The mark of waking life as compared with dream life is the far greater coherence in memory of experience of the former.
(25, A) This difference in degree of coherence of experience is sufficiently clear to escape the weakened EDH.
(26, FC) Under the weakened EDH I may count as knowledge that I am awake rather than asleep based on the far greater coherence in memory of the experience of waking life compared to dream life. (19, 24, 25)
(27, FC) Even under the weakened EDH, however, obscure and indistinct ideas regarding the material world are still doubtful, including (a) qualitative ideas regarding material things like color, smell, etc., and (b) ideas regarding the final causes of material things. (1-3, 19)