Philosophy 272: Handout D1

I. Deceptive Senses Argument: (Meditation I, Paragraph iii)

(1) My senses sometimes deceive me.
(2) Whatever sometimes deceives me should not be completely trusted.
(3) Thus, my senses should not be completely trusted.
(4) All my opinions/beliefs are obtained through the senses.
(5) Thus, all my opinions should not be completely trusted.

II. Dream Argument: (Meditation I, Paragraph v)

(1) Every waking experience, even the conscious and deliberate movements and perceptions of my body, is an experience I could have while dreaming.
(2) Thus, there is no definitive way of distinguishing being awake from dreaming I am awake.
(3) If there is no definitive way of distinguishing being awake from dreaming I am awake, then none of my experiences provides certainty.
(4) All of my beliefs are derived from my experiences.
(5) Thus, none of my beliefs is certain.

III. The Deceptive God Argument: (Meditation I, Paragraph ix)

(1) All my opinions about the world, mathematics, etc., could be brought about by an omnipotent God instead of by an actual existing world.
(2) If (1), then all my former opinions are uncertain.
(3) Thus, all my former opinions are uncertain.