Rene Descartes (1596-1650)
Meditation 1: Of Things 
Which May Be Brought Within the Sphere of the Doubtful
  • Objective: to arrive at certain truths to supply a foundation for the sciences{1}
  • method
    • doubt all that is in the least dubitable {2}
    • beginning with certain very basic beliefs on which many others are based {3}
      • e.g. the evidence of the senses
      • basis of our belief in the external world
  • Argument from hallucinations & illusions
    • senses sometimes deceive
    • therefore, their deliverances are generally suspect
  • Dream argument
    • no experiential evidence possible that all is not a dream {4}
  • the reliability of the senses impugned
    • it's doubtful that there is an external world
    • like what the senses seem to us to reveal
  • a priori -- non-observation-based -- truths survive, e.g., truths of mathematics
  • Evil Demon Argument {5}
    • a mighty evil genius is using all his powers to deceive me.
    • perhaps even my mathematical beliefs & beliefs concerning what I take to be conceptual "truths" are m mistaken. 
  1. "I must once, for all, seriously undertake to rid myself of all the opinions which I had previously accepted and commence to build anew from the foundation, if I wanted to establish anything firm and lasting in the sciences."(5)
  2. "[Since] reason already persuades me that I ought no less carefully withhold my assent from matters which are not entirely certain and indubitable than from those which appear to me manifestly to be false, if I am able to find in each one some reason to doubt, this will suffice to justify my rejecting the whole."(5)
  3. "[O]wing to the fact that the destruction of the foundations of necessity brings with it the downfall of the rest of the ediface, I shall only in the first place attack those principles upon which all my former opinions rested."(5)
  4. "I see so manifestly that there are no certain indications by which we may clearly distinguish wakefulness from sleep."(5-6)
  5. "I shall then suppose . . . some evil genius not less powerful than deceitful, has employed his whole energies in deceiving me; I shall consider that . . . all . . . external things are but illusions and dreams of which this genius has availed himself to lay traps for my credulity.(7)
Meditation 2:

"Of the Human Mind and That it is more easily known than the body.

Cogito Argument & Thought Experiment

  • assume nonexistence of body: what the senses reveal is false
  • does not follow that I don't exist
  • Conclusion: "I am, I exist"{2} the Archimedian Point {1}If I could think falsely "I exist": then I'd exist
    • if a demon is deceiving me
    • then I am deceived (hence existing)

Further conclusion concerning self's nature

  • bodily characteristics not essential to me
    • assumed nonexistence of my body
    • doesn't entail my nonexistence
  • not identifiable with lower Aristotelean "powers"  of
    • nutrition& growth
    • sensation
  • "identifible with the power (or exercise) of reason: "to speak accurately I am not more than a thing which thinks."{4}
  • Expansion of Archimedian Point: "I am" too slim a foundation
    • Existence of thoughts as well as thinkers indubitable{5}
    • Self portrayed as a field of "inward" subjective conscious experiences. {5}
    • denatured "sensations" also indubitable mental contents{7}
  • Concerning the nature of bodies & our knowledge of them: e.g., the wax
    • all the sensible qualities are inessential
    • reason alone reveals the true nature of matter as extended substance.{8}
  1. "Archimedes, in order that he might draw the terrestrial globe out of its place . . . demanded only that one point should be fixed and immovable, in the same way I shall have . . . high hopes if I . . . discover one thing only which is certain and indubitable."(7-8)
  2. "'I am, I exist' is necessarily true each time that I pronounce it, or that I mentally conceive it."(8)
  3. "[Thought] alone cannot be separated from me."(9)
  4. "To speak accurately I am not more than a thing which thinks, that is to say a mind or a soul, or an understanding, or a reason."(9)
  5. "What is a thing which thinks? It is a thing which doubts, understands, [conceives], affirms, denies, wills, refuses, which also imagines and feels."(9)
  6. "It is so evident that it is I who doubt, who understand, and who desire, that there is no reason here to add anything to explain it."(10) [Foreshadowing Hume's critique.]
  7. "[S]till it is at least quite certain that it seems to me that I see light, that I hear noise and that I feel heat. That cannot be false; properly speaking it is what is in me called feeling; ande use in this precise sense that is no other than thinking."(10)
  8. "We must then grant that I could not even understand through the imagination what this piece of wax is, and that it is my mind alone that perceives it."(11)
  9. "I see clearly that there is nothing that is easier for me to know than my own mind."(12)
Meditation 3: Of God: That He Exists


  • All he knows so far: a thinker -- this "I" -- and its thoughts: exist
  • How he knows: clarity and distinction of his "'perception" of it: by intellectual intuition or "the natural light"(1)
  • things whose denials would be self-contradictory are true(2) 
  • Residual doubt if God is a deceiver?
  • Classification of Thoughts

  • motives (volitions) & emotions (affections)
  • ideas: innate, adventitious, invented (3)
  • judgments: true or false combinations of ideas
  • Analysis of perceptual error: the error resides

    • not in the ideas (appearances) themselves
    • in the "uptake" -- the judgement that
      • these ideas are caused by external things
      • & that the external things resemble these ideas (4)
    • comparison to morality (5)
      • natural impulses to believe (there's an external world that's just so) comparable to natural impulses to act 
      • natural light of intellectual intuition steers us right . . . a kind of epistemic conscience 

    Objective reality & ideational content 

    • considered as representative {6}
    • ideas vary in objective reality content : modes or accidents < substances < God 

    Maker's Mark Argument

    • There must be as much reality in the cause as the effect (7)
    • An idea with X amount of objective reality must have a cause that has at least X amount of formal reality. (8)
    • I find in myself an idea of God that is possessed of infinite objective reality (9)
    • Only God could cause such an idea.
    • So, God exists. (10)

    Honest God Argument

    1. Deception necessarily proceeds from some defect {12}
    2. God has no defects.
    3. God is no deceiver 
    1. I can establish as a general rule that all things which I perceive very clearly and distinctly are true.(12)
    2. Let who will deceive me, He can never cause . . . any . . . thing in which I see a manifest contradiction. (13)
    3. Among . . . ideas, some appear . . . to be innate, some adventitious, and others to be formed [or invented] by myself. (13)
    4. [T]he principle error and the commonest . . . consists in my judging that the ideas which are in me are similar or conformable to the things which are outside me; for . . . if I considered the ideas only as certain modes of my thought, without trying to relate them to anything beyond, they could scarcely give me material for error. (13)
    5. But as far as [apparently] natural implulse are concerned . . . when I had to make active choice between virtue and vice . . . they often enough led me to the part that was worse; and this is why I do not see any reason for following them in what regards truth and error. (14)
    6. When we consider [ideas] as images, one representing one thing and the other another, it is clear that [some] . . . contain so to speak more objective reality within them [that is to say, by representation participate in a higher degree of perfection] than [others]. (14)
    7. Now it is manifest by the natural light that there must be as much reality in the efficient and total cause as in the effect. (14)
    8. But in order that an idea should contain some one certain objective reality . . . it must without doubt derive it from some cause in which there is at least as much formal reality as this idea contains of objective rearlity. (15)
    9. By the name God I understand a substance that is infinite, independent, all-knowing, all-powerful, .and by which I myself and everything else, if anything else does exist, has been created.(16)
    10. God, in creating me, placed this idea within me to be like the mark of the workman imprinted on his work. (19)
    11. [T]he light of nature teaches us that fraud and deception necessarily proceed from some defect. (19)
    Meditation 4:

    Of the True and the False

    • The problem of error
    • God is not a deceiver
    • But my God-given trust in my senses deceives me 
    • Error as pure negation: Augusintian theodicy (rejected)
    • error not pure negation (compare ignorance)
    • rather seems the lack of something I ought to have 
    • Explanation
    • inscrutability of God's ends . . . important aside (1)
    • mismatch between will & understanding (2,3)
      • will has the broadest compass 
      • understanding narrower in scope (4)
    • Justification (of the ways of God to us)
    • Ennobling character of this peculiar imperfection: [I]n a certain sense more perfection accrues to my nature from the fact that I can form [acts of will which lead me astray] than if I could not do so. (23)
    • The big picture: [I]n some sense it is a greater perfection in the whole universe that certain parts should not be exempt from errors. (23)
    • God has given me the ability to avoid being deceived (5)
      • to withhold assent from the dubious deliverances of the senses.
      • whether I err or not is up to me
    1. [T]he species of cause termed final, finds no useful employment in physical [or natural] things; for it does not appear to me that I can without temerity seek to investigate the [inscrutable] ends of God. (20)
    2. It is free will alone or liberty of choice which I find so great in me that I can conceive no idea to be more great [and] it is for the most part this will that causes me to know that in some manner I bear the image and similitude of God. (21)
    3. [T]he faculty of will consists . . . alone in the fact that in order to affirm or deny, persue or shun those things placed before us by the understanding, we act so that we are unconscious that any outside force constrains us in doing so. (21)
    4. Whence come my errors? They come from the sole fact that since the will is much wider in its range and compass than the understanding, I do not restrain it within the same bounds, but extend it also to things which I do not understand. (22) 
    5. [A]s often as I restrain my will within the limits of my knowledge so that it forms no judgment except on matters which are clearly and distinctly represented to it by the understanding, I can never be deceived. (23)
    Meditation 5:

    Of the Essence of Material Things, and, Again, of God That He Exists

    • Two varieties of mind independent things
    • particulars: objects
      • clearly and distinctly conceived as modes of matter
      • matter = extended substance
      • indestructible & not naturally generated 
      • occupying space
    • universals (properties, " natures, forms, or essences" (1) 
    • Ontological Proof (2)
    • The idea of God is "the idea of a supremely perfect Being" (2) 25)
    • Existence is a good thing or "perfection"
    • Therefore: God exists.
      • just one since "it is not possible for me to conceive two or more Gods in the same position (p. 26).
      • eternally: " I see clearly that it is necessary that he should have existed from all eternity" (p. 26).
    1. When I imagine a triangle, although there may nowhere in the world be such a figure outside my thought, or ever have been, there is nevertheless in this figure, a certain determinate nature, form, or essence, which is immutable and eternal, which I have not invented, and which in no wise depends on my mind. (24)
    2. I not less find the idea of God, that is . . . the idea of a supremely perfect Being, in me, than that of any figure or number. \(25)
    3. I clearly see that existence can no more be seperated from the essence of God than can its having its three angles equal to two right angles can be separated from the essence of a triangle, or the idea of a mountain from the idea of a valley. (25)
    4. [N]ot that my thought can bring this to pass, or impose any necessity on things, but, on the contrary . . . the necessity which lies in the thing itself . . . determines me to think this way.(25) 
    Meditation 6:

    Of the Existence of Material Things, and of the Real Distinction between the Soul and Body of Man

    • Imaginaton <> Intellect
    • Chiliagon v. Myriagon thought experiment
      • can distinguish conceptually
      • what we can't distinguish imaginatively
    • Power of Imagination is inessential to self/thinker
    • Hypothesis
      • imaginative power depends on something besides thought
      • it depends on the presence of "corporeal images"
    • Probably bodies exist: inference to the best explanation of imagination
    • Proof of the Existence of the External World
    • My faculty of perception is passive or receptive
    • Must be an agent power of producing the perceptual images
      • can't be in me (qua thinker) without be my knowing it
      • so it must be in another: either spirit or body
      • not a spirit -- whether God or another
      • since I'd be irremediably deceived 
      • God would be a deceiver -- or abetting my deceit 
    • Therefore, the cause is physical: the external world exists
    • Not much like it it appears on its face
      • sensuous qualities are not in the things (just their images)(4)
      • rationally apprehended (primary) qualities intrinsic to things 
        • figure & motion
    • Mind & Body (How the twain shall meet)
    • their natures {8}
      • minds: thinking, unextended, indivisible things
      • body: unthinking, extended, divisible stuff
    • the problem re "intermingling" {6}
      • hard to understand how minds can physically affect or be affected by anything
      • how bodies can mentally affect or being affected by any thought 
      • and yet it seems they do {7}
      • physical changes cause thoughts: sense perception
      • thought causes bodily motion: willed acts
    • the minimalization strategy (9)
      • don't see how they can intermingle
      • but they donít have to intermingle much
      • just in the pineal gland
    1. [I]t may happen that in imagining a chiliagon, I confusedly represent to myself some figure, yet it is very evident that this figure is not a chiliagon since it in no way differs from that which I represent to myself when I think of a myriagon or any other manysided figure. (27) 
    2. This power of imagination . . . inasmuch as it differs from the power of understanding, is in no wise a necessary element in my nature . . . from which we might conclude that it depends on something which differs from me. (28)
    3. [Imagination] differs from pure intellection . . . inasmuch as the mind in its intellectual activity in some manner turns on itself and considers . . . ideas which it possesses in itself; while in imagining it turns toward the body . . . . (28)
    4. For because God is nowise a deceiver, it follows that I am not deceived in this [belief in the external world]. (35)
    5. [I]n approaching fire I feel heat, and in approaching it a little too near I even feel pain [and] there is . . . no reason in this which could persuade me that there is in the fire something resemblin this heat any more than there is something resembling the pain; all that I have any reason to believe from this is that there is something in it, whatever it may be, which excites in me these sensations of heat or pain. (32)
    6. [Although] I possess a body with which I am very intimately conjoined. . . . it is certain that this [that is to say, my soul by which I am what I am[ is entirely and absolutely distinct from my body, and can exist without it. (30) 
    7. Nature also teaches me by the sensations of pain, hunger, thirst, etc. that I am not only lodged in my body as a pilot in a vessel, but that I am very closely united to it, and so to speak so intermingled with it that I seem to compose with it one whole. (31)
    8. [Body] is by nature always divisible, and the mind is entirely indivisible. (33)
    9. [T]he mind does not receive the impressions from all parts of the body immediately, but only from one of its smallest parts, to wit, from that in which the common sense is said to reside. (33)
    10. I consider the body of a man as being a sort of machine so built up and composed of nerves, muscles, veins, blood and skin, that though there were no mind at all, it would not cease to have the same motions as at present, exception being made of those movements which are due to the direction of the will and in consequence depend on the mind [as opposed to those which operate by the disposition of the organs. (32)
    Discouurse on Method & Related Passages
    • Other minds problem: what things besides myself are thinking things?
    • two tests for creativity 
      • language test
      • behavior test
    • conclusions 
      • other humans beings think:: only immaterial thought could account for creative character of speech and behavior evidence
      • no other animals think
      • since they lack creativity
      • mechanical principles suffice to explain all they do
    1. [S]ince the mind when engaged in private meditation, can establish its own thinking but cannot have any experience to establish whether the brutes think . . . it must tackle that question later on, by an a posteriori investigation of their behavior. (Reply to Gassendi)
    2. [Animals] are destitute of reason . . . and . . . it is nature that acts in them [mechanically]. (2)
    3. [I]f there were machines bearing the image of our bodies, and capable of imitating our actions as far as it is [practically] possible, there would still remain two most certain tests whereby to know that they were not therefore, really men. Of these the first is that they could never use words or other signs arranged in such a manner as is competent in us in order to declare our thoughts to others . . . so as appositely to reply to what is said in its presence. The second test is . . . to act in all the contingencies of life in the way in which our reason makes us act. (1)