St. Thomas and Descartes

Though this objection and response from St. Thomas don’t exactly speak to the famous dilemma of Descartes that founded modern philosophy, they are very suggestive of it. I’m not sure what to do with the text.

(quotation from St. Augustine) “There is no sensible thing that does not have some similarity to what is false, and, as a result, the two cannot be distinguished. To mention only one example: all that we sense through the body. Even when these objects are not present to the senses, we experience their images as though they were present, as when we are asleep or become delirious.” Truth, however, has no resemblance to what is false. Therefore, truth is not perceived by a sense.

One could similarly argue that every created thing has some similarity to what is false in so far as it has some defect. Nothing created, therefore, is truth, and so there is only one truth.

His response:

Although every creature has some similarity to what is false, created truth itself does not have this similarity. For a creature has some similarity to what is false in so far as it is deficient. Truth, however, does not depend on a creature in so far as it is deficient, but in so far as it rises above its deficiency by being conformed to the first truth.

De veritate, q. 1 a 4 ad 7.


  1. March 25, 2010 at 11:25 am

    Have you read the recently published book “Thomist Realism and the Linguistic Turn?” If not then you should. I think that it may help draw out a fuller understanding of Thomistic Epistemology in order to help you orient your thoughts about this passage. Also elsewhere in the QDV he makes some subtile distinction about where truth is found properly v. improperly and primarily v. secondarily.

    The problem with applying this specific case you cite with reference to the famous Cogito is that Thomas and Descartes are effectively working from different first principles. Thomas believes it to be absurd to doubt the existence of the world and as a result due to the very nature of being as communicable that we can know things. The opposite is true for Descartes.

    It is hard for there to be a conversation between participants who do not share first principles. Hence, I’m not sure if it is possible to dialogue with Descartes. Rather, it seems to me, that we must convince people that Thomism is more coherent.

  2. March 25, 2010 at 11:37 am


    Wow, A real religious! Cool.

    I think, happily enough, that the article you are thinking about in QDV is the corpus of the article I quoted. Truth is in God properly and primarily; in man properly and secondarily; and in things improperly and secondarily. I almost wrote about that yesterday.

    I’d agree that St. Thomas and Descartes do not start from a common principle, but this quotation above might help to illumine why. I had in mind asking something like “given that there is some similarity between the dream objection here and Descartes’s evil deceiver, what are the points of commonality and difference?” There are some easy answers to this (the dream argument is not meant to show a radical doubt) but there are also some trickier questions (Are St. Thomas and Descartes agreeing that there is always something false about what man experiences it through his senses?).

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