Everyone has four eyes, or: why optometrists are stupid.

The Ones that are Held for Pleasure

Originally uploaded by Pete Mandik.

1. Assume, for simplicity, that everyone has two eyes that they see with (apologies, then, to pirates and cyclopses).

2. Assume, for simplicity, that everyone has two eyes that are seen (again, apologies).

3. Eyes that are seen are objective, that is, everyone else can see them.

4. Eyes that you see with are subjective, that is, only you can see with them.

5. Eyes that are seen are spatial (they have locations and shapes) and this is readily observable.

6. Eyes that you see with are nonspatial (they have neither locations nor shapes) since they occupy no position or amount of the visual field.

7. Eyes that are seen with cannot be identical to eyes that are seen since an objective spatial thing cannot be identical to a subjective nonspatial thing.

Therefore, everyone has four eyes.

12 Responses to “Everyone has four eyes, or: why optometrists are stupid.”

  1. Paul Gowder says:

    Haha, I love your smart-ass remarks. But I think there’s a problem in 6: why should a spatial object occupy some part of the visual field. Would a perfectly transparent piece of glass be nonspatial?

  2. Pete Mandik says:

    Thanks, Paul.

    I think the person that liked the above argument should also go for something like this:

    When I touch things in places these are unseen things in unseen places. The objects of touch exist in a spatial manifold distinct from that of sight. So the argument in the post should have spatial replaced with visuo-spatial.


    If I use my spatial sense in touch to touch some eyes, then I am touching neither eyes that are seen with nor eyes that are seen. I am touching eyes that are touched.

    Therefore, we actually have six eyes. (at least)

  3. Pete Mandik says:

    Also, I recommend The Simplicity of Santa, by Eric Steinhart.

  4. Richard Brown says:

    lol, you are funny :)

    but these word games do not really show that there is some absurd result if we acknowledge phenomenal reality

  5. Hi Pete,
    How about mirrors?
    I see they eyes I see with in the mirror.

  6. Pete Mandik says:

    The eyes in the mirror don’t see anything at all, so they can’t be the eyes that you see with.

  7. charles says:

    I couldn’t help but think the following — where am I going wrong?

    “Electrons/gravitational waves/each person’s brains are nonspatial, since they occupy no position or amount of the visual field.”

    Also seems that 7 is an invalid application of Leibniz’s Law^H^H^H^HFallacy.

  8. Pete Mandik says:


    Re: spatial, see my response above to Paul Gowder.

    Re: Leibniz’s Law, I don’t see what the problem is you have in mind. One problem might be that if the properties mentioned in 7 are intensional, then the inference won’t go through. Perhaps (with a lot of work it can be shown that) objectivity and subjectivity are intensional, but being spatial isn’t.

  9. Tad says:

    On an unrelated note - don’t know if you all have heard that Dan Dennett had a ruptured aorta a couple of days ago - this according to David Chalmers. Usually this is fatal, but he’s recovering after 9 hours of surgery.

  10. Pete Mandik says:

    That’s the first I’ve heard of it. I certainly hope the best for Dan and his family.

  11. Chandra says:

    What about tactical presence. Eyes with which you see are not fitting into your field of vision that’s it. But since you tactically feel their presence and appreciate their size and shape your argument goes in Vain!

  12. Chandra says:

    If your explanation of the eyes in the mirror dont see at all works. Then the body to which they belong is definitely not be yours else you will have twice the number of all the body parts.

    I am taking this too far. Never mind.: