The following argument against God’s existence using Cartesian scenarios was presented to me by someone who codified a position being proposed by an atheist in a particular chat room discussion. I listened in and asked for him to write it out so I could reproduce it and address it on CARM. He did not – probably due to the nature of the chat room discussion. But, he did continue to explain it to me. The connection was not very good, so I had difficulty writing out his argument. But, someone else in the discussion did, and sent it to me.

If this argument is not an accurate representation of the atheist’s position, then my apologies. If that is the case, I hope to deal with it when presented at a later time. Nevertheless, the following argument thus presented deals with the God of Classical Theism and Cartesian Scenario as a refutation for omniscience. If omniscience is possible, then an omniscient God cannot exist and the God of classical theism cannot exist.

In order to address this argument, we must first define the two main terms presented in it: the God of classical theism, and the Cartesian scenario. The argument given to me did not include the definitions of these terms. So, I did some research and provided three definitions of each term. I will then analyze the supposed argument against God’s existence based on the following definitions.

Finally, I present the original argument in bold and then respond to each point immediately afterward following with a bolded Matt

• God of Classical Theism
  • The God of classical theism is the ultimate, simple, non-contingent, immaterial, not spatially extended, without accidents (no contingent attributes), immutable (unchanging), impassible (unaffected by others), eternal, necessary, omnipresent, omniscient, and omnipotent. (Extracted from  https://www.rep.routledge.com/articles/thematic/god-concepts-of/v-1/sections/classical-theism)
  • The God of classical theism is incorporeal, simple, unity, eternal, omnipotent, omniscient, impassable, good, etc. (Extracted from https://iep.utm.edu/god-west/)
  • “Classical theism’s God is infinite or unlimited in not depending on other things, and in perfection, power, knowledge, goodness and creative responsibility” (https://askinglot.com/what-is-the-god-of-classical-theism)
• Cartesian Scenario / Cartesian Skepticism
  • A cartesian scenario is a scenario in which a mind is deceived by such things as hallucination, living in the Matrix, demons, etc. (I heard the atheist present these preceding options.) Cartesian skepticism is “Any of a class of skeptical views against empirical knowledge based on the claim that claims to empirical knowledge are defeated by the possibility that we might be deceived insofar as we might be, for example, dreaming, hallucinating, deceived by demons, or brains in vats.” (https://sites.google.com/site/minddict/cartesian-skepticism)
  • “Descartes considers the hypothesis that there is a powerful evil demon who renders his beliefs about the world false, while making it seem to him just as if they are true.” (https://philpapers.org/browse/cartesian-skepticism)
  • “The Cartesian Skeptic describes an alleged logically possible scenario in which our mental lives and their histories are precisely the same as what they actually are, but where the causes of the facts about our mental lives are not the kinds of events in the external world that we commonly think they are. On Descartes’ Evil Genius hypothesis, there is no physical world. Rather you are a disembodied mind, and your entire mental life, with all of its experiences, has been caused by an all-powerful, purely spiritual Evil Genius. As a result, your beliefs about the external world, such as that you have a body, or that there are planets in the solar system, are all mistaken.” (https://plato.stanford.edu/entries/skepticism-content-externalism)

 

The argument is as follows

• P1) If the God of classical theism exists, then God and creation exist as a mind without an external world
• P2) If God and creation exist as a mind without an external world, then Cartesian scenarios are logically possible
• C1) If the God of classical theism exists, then Cartesian scenarios are logically possible (HS 1,2)
• P3) If the God of classical theism exists and Cartesian scenarios are logically possible, then omniscience is impossible
• P4) If omniscience is impossible, then the God of classical theism cannot exist
• C2) Therefore, If the God of classical theism exists and Cartesian scenarios are logically possible, then the God of classical theism cannot exist (HS 3,4)

 

Let’s tackle the argument against God’s existence using Cartesian scenarios.

 

• P1) If the God of classical theism exists, then God and creation exist as a mind without an external world
  • Matt: The God of classical theism does not include the Trinitarian God, though it has many of the same characteristics. The Trinitarian God who is by biblical definition the ultimate being beyond which there is nothing greater. He knows all things without exception and does whatever He pleases.
  • Matt: Since I deny the possibility of all other gods than the Trinitarian God, I will address this argument in light of the Trinitarian God.
• P2) If God and creation exist as a mind without an external world, then Cartesian scenarios are logically possible
  • Matt: Why is it necessarily true that a mind that is immaterial and exists apart from an external world is automatically and logically subject to Cartesian scenarios, i.e., being deceived? Without a logically necessary connection, P2 is only an opinion. An opinion here does not make the argument valid.
  • Matt: In light of the Christian Trinitarian God who is, by definition, all-knowing, and in all places, it would not be possible for Him to be deceived. Therefore, this argument fails against the Christian God, since it does not represent it properly.
  • Matt: Deception would be either internal or external.
    • If someone proposes an internally deceived god (not the Trinitarian one), then it would not have all knowledge; otherwise, it would not be self-deceived. To say that this god only “thinks” that he has all knowledge would then mean he does not have all knowledge. But that would not be the “god of classical theism” – which is said to be omniscient). So, there seems to be a logical contradiction in P2 where a god(s) of classical theism both has all knowledge and also does not have all knowledge.
    • If someone proposes an externally deceived God, then this god does not have all knowledge and this again contradicts the definition of the “god of classical theism” which is supposed to have all knowledge. So, once more there seems to be a logical contradiction in P2 since it proposes a god that both has all knowledge and also does not have all knowledge.
  • Matt: P2 offers a situation that is not possible with the Trinitarian God who, by definition, knows all things and therefore cannot be deceived. If the critic argues that just defining the Christian God as not deceivable does not invalidate the argument, then just defining the cartesian scenario as possible does not validate the argument, either.  After all, what must be in place in order for a Cartesian scenario to be valid?
    • Brains in a vat  If we are merely brains in a vat, then what conditions must be in place in order for that possibility to exist? Do we dip into solipsism here? Are all our brains in one vat, or individual vats? Brains in a vat? Seriously? If the conditions cannot be rationally supported, then why entertain it as a possibility? Furthermore, if we are brains in a vat, how would that invalidate an omniscient God’s existence since the vat-owner’s existence does not by default invalidate the omniscient God’s existence beyond him?
    • Evil Deceiving Demon  If there is an evil demon that is deceiving us, then what conditions must be in place in order for it to actually exist?
      • It would have to have greater knowledge and scope than the God of classical theism. But, this contradicts the definition of the God of classical theism.
      • It would have to have greater knowledge and scope than the Trinitarian God. But, this contradicts the definition of the Christian Trinitarian God.
    • If the critic says that simply defining the Christian Trinitarian God as not being deceived is not valid, then I can respond and say that simply defining the demonic forces as being capable of deceiving the Trinitarian God is not valid.
  • Matt: Escaping its own skepticism How can the person proposing the argument, know that the argument is not an extremely clever deception offered by a scientist who has him in a brain-vat, or that there is an incredibly clever demonic force deceiving him into denying that God actually exists? After all, to say the argument is based on logic could be countered by saying that the one presenting the argument is deceived about his own logic. After all, does the critic know all logical principles? Also, does he know the complete state of his own mind so as to accurately discern that he isn’t deceived into thinking the argument is valid?  Therefore, the P2 implies that P2 cannot be known to be true.
• C1) If the God of classical theism exists, then Cartesian scenarios are logically possible (HS 1,2)
  • Matt: A Cartesian Scenario
    • Matt: C1 is based on P2 which has problems. Therefore C1 is not necessarily true.
• P3) If the God of classical theism exists and Cartesian scenarios are logically possible, then omniscience is impossible
  • Matt: P3 contradicts the definition of the God of classical theism from which it argues. Essentially it is saying the God of classical theism knows all things but also does not know all things. Therefore, P3 is not necessarily true.
• P4) If omniscience is impossible, then the God of classical theism cannot exist
  • Matt: while it would be true that if omniscience is not possible, then the God of classical theism cannot exist, the preceding argument does not establish the impossibility of omniscience. Therefore it has not negated the possibility of the God of classical theism.
• C2) Therefore, If the God of classical theism exists and Cartesian scenarios are logically possible, then the God of classical theism cannot exist (HS 3,4)
  • Matt: the argument has not established that Cartesian scenarios are logically possible.  as stated above, both the internally and externally deceived God would, by definition not be omniscient. But, since the God of classical theism is by definition omniscient, there is a contradiction in the argument.

Conclusion

The argument against the existence of the God of classical theism using Cartesian scenarios appears to have internal contradictions. Therefore, its conclusion has not been demonstrated to be true.