1. 2 Descartes on God and His Existence

2. TAs
none

3. Bibliographical Resources (reminder):
Descartes’ Meditations (with Critics and Replies) + Discourse free at:
Leibniz’s Nouveau Essays free at:

4. Further bibliography on Descartes:
Cottingham J. (1986). Descartes. Blackwell, Oxford
Further bibliography on/by Chomsky:
Chomsky N. (2000). New Horizons in the Study of Language and Mind. Cambridge UP: Cambridge
McGilvray J. (1999). Chomsky: Language, Mind, and Politics. Polity Press: Cambridge

5. The following can also be useful
Antony L. M. & Hornstein N. (eds.) (2003). Chomsky and His Critics. Blackwell: Oxford
Smith, N. (1999) Chomsky: Ideas and Ideals. Cambridge UP: Cambridge
Wilson C. (2003). Descartes’s Meditations: An Introduction. Cambridge UP: Cambridge

6. The Need of God
Main Goal: To discover the fundamental ideas and notions, the innate truths, that God implemented in us.
God’s Existence: Descartes proposed a causal explanation, but the effects he focuses on are entirely within the mind.

7. The Trademark Argument
God has placed within us the idea of himself as a craftsman’s stamp on his work.
This argument presents four phases:

8. 1. To make an inventory of the ideas. found within oneself
1. To make an inventory of the ideas found within oneself. The chief idea Descartes founds is the one of a supreme God, eternal, infallible, omnipotent and the creator of all things that exist a part of Himself.

9. I decided to inquire into the source of my ability to think of something more perfect than I was; and I recognized very clearly that this had to come from some nature that was in fact more perfect. … it was manifestly impossible to get this [idea] of a being more perfect than my own. For it was manifestly impossible to get this from nothing; and I could not have got it from myself since it is no less contradictory that the more perfect should result from the less perfect, and depend on it, than something should proceed from nothing. So there remained only the possibility that the idea had been put into me by a nature truly more perfect than I was and even possessing in itself all the perfections of which I could have any idea, that is—to explain myself in one word—by God. (Discourse on the Method; CSM I: 128)

10. 2. The Causal Adequacy Principle.
It’s the self-evident principle that there must be as much reality in the efficient and total cause that there is in the effect of that cause: ex nihilo nihil fit.

11. [T]he objective reality of our ideas needs a cause which contains this reality not merely objectively but formally or eminently. It should be noted that this axiom is one which we must necessarily accept, since on it depends our knowledge of all things, whether they are perceivable through the senses or not. How do we know, for example, that the sky exists? Because we see it? But this ‘seeing’ does not affect the mind except in so far as it is an idea—I mean an idea which resides in the mind itself, not an image depicted in the corporeal imagination. Now the only reason why we can use this idea as a basis for the judgement that the sky exists is that every idea must have a really existing cause of its objective reality; and in this case we judge that the cause is the sky itself. And we make similar judgements in other cases. (Second Set of Replies; CSM II: 116-7)

12. 3. The Causal Adequacy Principle also applies to the realm of ideas and the features depicted by them (ideas are often conceived along images).
E.g. if an idea X depicts/represents an object which is F, then the cause of the idea must itself contain at least as much F-ness as it must be found/represented in the idea X.

13. 4. Given (1), i.e. that I have an idea of God being eternal, omnipotent, benevolent, etc. it follows from (2) and (3) that:
The cause of my idea must contain in itself all the features represented by my ideas.

14. Since I am a finite and imperfect being I cannot myself be the cause of this idea representing perfection, omnipotence, etc.
The ultimate cause of my idea of God must be something possessing all these perfections represented in my idea.
Thus God exists.

15. Thoughts are about things as images are images of things.
Ideas are images
Thoughts are about things as images are images of things.
Some of my thoughts are as it were the images of things, and it is only in these cases that the term ‘idea’ is strictly appropriate—for example, when I think of a man, or a chimera, or the sky, or an angel, or God. (Third Meditation; CSM II: 25)

16. Ideas, as images, cannot in themselves be false.
Now as far as ideas are concerned, provided they are considered solely in themselves and I do not refer them to anything else, they cannot strictly speaking be false; for whether it is a goat or a chimera that I am imagining, it is just as true that I imagine the former as the latter. (Third Meditation; CSM II: 26)

17. Causal Adeq. Princ. + Ideas as images  God
Now it is manifest by the natural light that there must be at least as much <reality> in the efficient and total cause as in the effect of that cause. For where, I ask, could the effect get its reality from, if not from the cause? And how could the cause give it to the effect unless it possessed it? It follows from this both that something cannot arise from nothing, and also that what is more perfect—that is, contains in itself more reality—cannot arise from what is less perfect. … if we suppose that an idea contains something which was not in its cause, it must have got this from nothing; yet the mode of being by which a thing exists objectively <or representatively> in the intellect by way of an idea, imperfect though it may be, is certainly not nothing, and so it cannot come from nothing. (Third Meditation; CSM II: 28-9)

18. [I]deas in me are like <pictures, or> images which can easily fall short of the perfection of the things from which they are taken, but which cannot contain anything greater or more perfect. (Third Meditation; CSM II: 29)

19. Hierarchy of Ideas (ii) idea of finite substances
(i) idea of God
(ii) idea of finite substances
(iii) idea of accident and modes

20. Because of the Causal Adequacy Principle:
Descartes can argue that ideas of things less perfect than myself can be wholly invented/created by myself whereas ideas of things more perfectly than myself cannot be wholly created/invented by myself.

21. The idea of God is neither an
(i) an adventitious idea (coming from the senses)
(ii) nor invented.
It is simply found within the mind and yet it corresponds to something outside the mind.

22. The Idea of God is innate
It is innate, for if it cannot be caused by an external thing and yet corresponds to an external thing.
As such it must be stamped into the mind at the first instance of its existence.

23. By the word ‘God’ I understand a substance that is infinite, <eternal, immutable,> independent, supremely intelligent, supremely powerful, and which created both myself and everything else (if anything else there be) that exist. All these attributes are such that, the more carefully I concentrate on them, the less possible it seems that they could have originated from me alone. So from what has been said it must be concluded that God necessarily exists.
It is true that I have an idea of substance in me in virtue of the fact that I am a substance; but this would not account for my having the idea of an infinite substance, when I am finite, unless this idea proceeded from some substance which really was infinite. (Third Meditation; CSM II: 31)

24. Descartes does not discuss Marsenne’s assertion that there are human beings with no innate idea of God:
[T]he fact that the native of Canada, the Hurons and other primitive people, have no awareness of any idea of this sort seems to establish that the idea does come from previous held notions. (Marsenne; Second Set of Objections; CSM II: 89)
Furthermore Descartes does not tackle the question how there can be natural atheists if the idea of God is innate.

25. God as Final Cause Problem with Causal Adequacy Principle
The Causal Adequacy Principle does not seem to account for new or emergent properties.
E.g. the property of sponginess created in mixing and backing some flowers emerge from some chemical changes.

26. Idea of God? For, if ideas are images what is our image of God?
Hobbes (Third Set of Objections with Replies; CSM2: 127) objected that we cannot have an idea of God.
For, if ideas are images what is our image of God?

27. Hobbes:
But when I think of an angel, what comes to mind is an image, now of a flame, now of a beautiful child with wings; I feel sure that this image has no likeness to an angel, and hence that it is not the idea of an angel. But I believe that there are invisible and immaterial creatures who serve God … In the same way we have no idea or image corresponding to the sacred name of God. … It seems, then, that there is no idea of God in us. (Third Set of Objections with Replies; CSM II: 126-7

28. Descartes’ reply
Although ideas may be somewhat like picture or images they’re not actually images
‘idea’ stands for what is immediately perceived by the intellect.
One can know and understand something without fully grasping it.

29. Descartes’ Reply
Here my critic wants the term ‘idea’ to be taken to refer simply to the images of material things which are depicted in the corporeal imagination … I am taking the word ‘idea’ to refer to whatever is immediately perceived by the mind. (Third Set of Objections with Replies; CSM II: 127)

30. The Ontological Argument
It is an a priori proof of God’s existence.
One can imagine a triangle even if this figure were not to exist anywhere outside one thought. To do so it suffices to imagine that it has tree angles whose sum is 180 degrees, and so on.
Thus we can deduce that a triangle has an essence whether or not it exists outside our mind.

31. The same (a priori reasoning) with God
We can imagine his existence because the latter cannot be separated from his essence.
It would be contradictory to think of God (a supremely perfect being) lacking existence.

32. Lack of existence entails imperfection.
Since I must attribute all perfections to God and since existence is among the perfections, God cannot lack it.
Descartes’ argument rests on the very idea that existence, like omniscience and omnipotence, is a perfection. If so it should be a property of some kind.

33. But, is existence a property?
Cf., for instance, Frege’s view that existence is a second order predicate.

34. Importance of the Argument for God’s Existence
It constitutes the only way we can transcend the subjective self-awareness knowledge and progress to the knowledge of the external world and reality.
Thus within the Cartesian framework God can be viewed as a scientific posit/necessity.

35. The Avoidance of Error Yet we often do make mistakes.
We should recognize the impossibility for God to deceive.
Yet we often do make mistakes.
It seems thus that there should be evil in the world.

36. How do we conciliate the presence of error with the idea that God is perfect and benevolent?
To avoid error we should suspend most of our judgements. We should restrict them to the sphere of pure mathematics, which is the only reliable strategy for avoiding error.
Mathematical judgements constitute the paradigm of properties that the intellect can clearly and distinctly perceive.

37. Why mathematics?
Mathematical judgements help understanding reality insofar as ordinary three-dimensional objects can be defined in pure mathematical terms.

38. The physical nature is the proper subject of mathematical reasoning.
When we make errors we improperly embrace a proposition without having sufficient grounds for doing so. And we do so because the scope of our will transcend the scope of the intellect:
So what then is the source of my mistake? It must be this: the scope of the will is wider than that of the intellect; but instead of restricting it with the same limits, I extend its use to matter I do not understand. (Fourth Meditation; CSM II: 40)

39. Cartesian Circle
To prove God’s existence I need to trust my intellect.
Yet without prior knowledge of God’s existence I have in principle no reason to trust my intellect.

40. If all knowledge depends on God, then to know this premise (that all knowledge depends on God) one needs to prove the existence of God without first knowing God.
It is only on relying on clear and distinct ideas that Descartes can proves the existence of God, yet it is only by the existence of God that one can have clear and distinct ideas.

41. Out of the circle?
The way out of the circle is for Descartes to claim that there are certain propositions (e.g. cogito) presenting self-evident knowledge that one can grasp as long as one is attending them.
These self-evident propositions do not require God’s intervention.

42. The Need of God
Why on top of the self-evident elementary truth we need God?
Because of the temporary nature of these self-guaranteeing truths, i.e. because they last only as long as one is entertaining them.
Once God’s existence in established we can progress beyond the temporality of these self-evident truths.