Week 12a- Monday: Averroes, Aquinas, Bacon, Witelo on Vision

Welcome back.  Please post some thoughts on the readings assigned for Monday.  Pay particular attention to the Lindberg reading in contrast to the readings based on Aristotle’s De anima.  This section on optics has a dramatic arc that requires that you understand the distinction between the various optical theories.  Recall Lucretius too.  Pay particular attention to note 6 on page 393 and all of our endless discussions on souls, spirits, and forms… and now “species” too.

Back to Syllabus

15 thoughts on “Week 12a- Monday: Averroes, Aquinas, Bacon, Witelo on Vision

  1. From the Alhazen, Bacon, and Witelo readings, I was struck by the link that two of the authors made between pain and seeing.
    Alhazen writes ‘Since all are of one kind, and the operation of strong lights is a kind of pain, all actions of light are a kind of pain…’. From Witelo – ‘Sight occurs through the action of visible forms on the eye and the suffering of the eye on account of this form.
    sight also suffers from sensible forms, since it sometimes retains in itself their strong impressions.’
    I don’t know whether these two believed that seeing in general was a kind of pain, and that harm was being done simply through the act of seeing, but it is an interesting thought that by letting light into our eyes that we’re suffering in some way. I also wonder whether they might have advocated any treatment for this suffering, or if the pain was so slight that people would have simply endured it without even being aware that they were being hurt.
    It is also interesting, as described in the Lindberg reading, that this feeling of pain caused by bright lights was able to prove for Alhazen that the eye is the recipient of external action.

    • I wonder if feeling pain is another way of simply saying stimulated. This may be one of those situations where the vocabulary didn’t exist, or the translation is slightly too literal, or the author was coming from an unfamiliar philosophical place or all of the above or something else. Any of these possibilities are interesting. I certainly see what they mean. A really bright light is painful.. so in some sense a dimmer light is just less painful… but we don’t call it that. Where is the line between pain and not pain? Might it have been different in the past? Is the flick of a finger painful? When does it become painful?
      Pain sort of measures the intensity of the light.

  2. In the De Anima commentary, it took me a few read-throughs of certain sentences and paragraphs to understand the concepts Averroes is trying to communicate. One that was particularly difficult was the explanation of transparency and color, and how light is responsible, or not, for them. Later discussions of color refer back to the matter/form argument of Aristotle. For light in terms of color, Aristotle had explained the relationship of the two by saying that color exists even without light, because it is “visible without the mediation of a form accruing to it”. Light is not responsible for color existing, but only for our ability to see the color of things, or our visibility. There is a theory mentioned by Aristotle when dealing with color and light which is described as “everything which receives something receives it in only the way they are lacking it”. This comes up again when he is describing transparency, and stating that transparent things like water take on the colors around them because they are lacking them in their natural state. Is this a description of the process of reflection? The importance of having a medium with which humans use their vision through is mentioned throughout, as it is for other senses. He explains that if there was a vacuum, we would not see anything. Why was this seen as so important? Why did our vision need to be traveling through something else in their explanation?

    • “everything which receives something receives it in only the way they are lacking it”. That’s a great quote. It is sort of the teleology of Aristotle in a nutshell. Things are designed to respond to certain stimulations… it is part of their nature… eyes don’t hear, noses don’t see… Transparent medium doesn’t turn blue, it is either actually transparent or potentially transparent (a.k.a. dark or opaque).
      Everything needed to be in contact… seeing and touching were very similar… try to insert this into today’s conversation in class.

  3. It’s quite striking that Aristotle’s theory of vision dramatically reflects his thoughts on the soul and perception in that it is the eye(sensing organ) that projects the color and light on the object.. What is curious however, is the disagreement among the commentators on how this is possible or impossible.

    What is most important, I believe, is the discussion about light and color because the way an individual perceives these characteristics of objects ( along with others, smell, sound, etc) is dependent on the ability of the object to possess these characteristics to then be able to portray them for external perception. Most of the commentators would agree with this, however, with aristotle, there is a gap between the idea of perceiving and the emission of the object’s characteristics and this is why he disagrees with Democratus. In modern reality, Arostotle is correct to believe there cannot exist vacuity for the transmission of the senses, however, this is not true for light and sight.

  4. In the Alhazen, Bacon, and Witelo readings, I found what Bacon was saying to be confusing. I took what he wrote to be a convoluted version of “I think light is some sort of wave that cannot bounce off of certain surfaces the way sound does, and thus objects–not even the lynx as Aristotle assumes–cannot be seen around corners.” I do not understand why he had to complicate his message so much, as his message (which is mostly correct) seemed to get lost in his winded essay.

    I am not sure what Witello meant when he said the eye “suffers” when it sees. As sight is not actually a painful experience (granted the partaker is not staring directly at the sun), I can only assume he meant some other sort of experiencing. Alhazen said something similar, but went further to describe why light cannot be a wave. However, I do not fully understand his argument that light cannot be a wave because nothing bounces off of the eye; was it not possible to him that waves could just dissipate? Could this not have been observed while looking at the ocean?

    • I agree… that Bacon is a bit hard to follow. The lynx thing is funny… I’ll explain in class.
      I would tend to follow your idea that “pain” or “suffer” may not be the best word for this process, but perhaps it was the only one available at the time, or was in synch with other aspects of some other theory that we didn’t read about. E.g. If the sense of touch is either pain or nothing… just varying degrees of pain… which might better be translated as stimulation or some such word???

  5. Suddenly as I was reading Averroes’ commentary on DeAnima, I noticed that it sounded like Lewis Carroll’s “Alice in Wonderland.” It seemed, to me, that Averroes is rounding himself on the same ideas that Aristotle has come up with, and these ideas are so specifically detailed and described, that it begins to sound like nonsense. In Alice in Wonderland, many of the descriptions of events are done in such a way that the topic, though absurd, is justified through language and conclusions drawn by Alice. When reading the first excerpt on page 175 of Averroes’ commentary, I noticed the description of the senses taking on this absurd characteristic that seems inherent in over-explaining. I suppose this thought becomes relevant when I address the idea of the word “sensible” in terms of it being “proper,” for despite reading and rereading these paragraphs, I cannot even begin to figure out what that means on a serious level. I just keep thinking about Alice in Wonderland… perhaps it rests in the translation, and for this digression, I apologize, it was simply a thought that can further be investigated but will be something I do on my own. Averroes then compared proper things to common things, such as shape. I would like to then argue that all aspects of these senses become common, for sound may be distinct but still issues from an object wit other common traits. There seem to be no proper traits, in my understanding, although it is argued using darkness, but that only eliminates one sense, and why should sight be the sense that determines the state of proper senses? I do see that Averroes brings up some questions about Aristotle’s reasoning. It was interesting to then read Aquinas’ commentary, for it was much more about his assumptions and conclusions… AH! Senses being affected by sensible qualities! so much more sense can be made out of his argument than Avverroes’.

    • These medieval commentators are rarely studied for a reason. They are really complicated and often refer to stuff that is totally unfamiliar, using strange vocabulary. You are right to feel like you have entered Alice’s Wonderland.
      Yeah, the Aquinas reading was a bit easier to follow. But Aquinas’ commentary on the section we read by Averroes was twice as long. I decided not to add the extra 10 pages to the reading.
      These guys were obsessive.

  6. The Averroes reading was incredibly complex and dense in the explanation of sensation. This is understandable because sensation is a tough notion to conceptualize (even knowing what we know now about physics and biology). When going through the readings a several questions came to mind. I was wondering what Aristotle might have to say about synesthesia. Also when talking about senses sensing their sense, how about how you taste lessens without smell? What did they think about bats flying in the dark? Animals making noise under water? In the Aquinas reading when he talks about how plants cannot sense, did they not notice plants growing in the direction of sunlight? Or leaves slowly moving to absorb more sunlight?
    I think the discussion of whether a medium is necessary for sensation is interesting. Aristotle holds that one cannot see within a vacuum which is false. But it is true that one cannot hear in a vacuum. Also, I think he touched on an interesting dichotomy of the presence of something like light vs the presence of darkness. Is darkness a thing? Is it only the absence of light?

    • Indeed. Who, among us, can explain how vision works? Seriously.
      Ah! I’m so glad you mentioned synesthesia! Bring it up in class.
      … and bat sonar too…. very topical for theorists like Euclid and Galen.
      Your counter examples about plant sensation are great. Plants clearly sense something.. and Aristotle should have seen this.
      Darkness.. light.. transparent.. color… oh my!

  7. Averroës’s commentary on De Anima had my head spinning a little bit, but I really enjoyed it. I saw many parallels, or rather early ground work for later theories of light. Averroës and Aristotle were on to the motion of light, for example. Also, Aristotle said that “everything which receives something receives it in only the way they are lacking it” which dovetails nicely with color theory today, namely that an object will appear red (for example) if it absorbs all other wavelengths of light except red, which it reflects. In a way, Aristotle could argue that the object doesn’t absorb red waves because it IS red; in other words, it does not receive red because it is not lacking red. And why would it not be lacking red? Because it IS red. This is the most compelling argument for the intrinsicality or essential nature of color I think we could hear.

  8. The Lindberg reading was helpful in laying out and drawing comparisons between a number of ancient philosophers’ theories on vision. I was pleasantly surprised to get the chance to review Lucretius’ film theory, in which we are all emanating our own films which then enter other peoples’ eyes, etc…

    But really, the most interesting part for me was in the discussion of how Aristotle explained transparency. How transparent objects are not themselves a “thing,” but rather a medium through which things that are separate from us are able to seen; light, he claims, is such a medium. Light is the “allowing” medium that gives “us” (our soul, our being) the ability to sense and see the forms of other souls (and other things generally).

    I have to admit that I was thrown during the discussion of light and color as transparent media that affect and move one another, and how our eyes essentially “become” what they are seeing as opposed to merely perceiving it. Although this assertion is kind of cool if it means that whenever we see our friend, we are kind of becoming our friend…right? Clearly a little confused here.

Leave a Reply