Saturday, August 25, 2012

Hass on the Muller-Lyer



It is not unusual to see writers use this illusion to conclude that perception is a merely subjective event: "The two lines appear to be different lengths, when objectively they are the same; therefore, perception is subjective appearance, which hides objective reality." This reasoning is specious, common though it may be. Just because one can construct (with a ruler) some numerically determinate figure that we perceive indeterminately, does not entail the ontological claim that fundamental reality is a collection of fully determinate objects and perception a mere subjective appearance.
Lawrence Hass. Merleau-Ponty's Philosophy (pp. 37-38). Kindle Edition. 
Maybe some readers can help me with the foregoing passage.  So, I'm willing to entertain the view that this reasoning in the quotation is specious and that perception is not subjective appearance.

And, I agree that just because one can construct (with a ruler) some numerically determinate figure that we perceive indeterminately, does not entail the ontological claim that fundamental reality is a collection of fully determinate objects and that perception is a mere subjective appearance.

I also agree that just because one can construct (with a ruler) some numerically determinate figure that we perceive indeterminately, does not entail the ontological claim that fundamental reality is a collection of fully determinate objects.

But, I don't see how the view of perception is supposed to be linked to the theory of fundamental reality.  (I would have thought that all one needs is that appearance differs from reality. ) How is this supposed to work?  Honest question.


9 comments:

  1. Do you mean you don't see how to link 'fundamental reality is a collection of fully determinate objects' to 'perception a mere subjective appearance'?

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  2. Isn't it just as you said: the claim is that you can demonstrate 'errors' such as the Muller Lyer and thus perception is not the same as an objective measurement, leaving you with the idea that it's subjective?

    As this quote lays out, this is poor reasoning. But it's always seemed to me that this was the chain of logic: measure the world with physics, measure the world with perception, compare; if different, perception is in error and thus subjective.

    Am I missing something?

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  3. Right, so there is an appearance reality distinction for the reason offered. Contrary to Hass, this is not specious. Right?

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  4. There's the issue of 'measured by what?' - you get different numbers for that line length from an inch vs a cm ruler. Is one objective, the other subjective? The point, crudely, is that your answer depends on your measurement device and it's not clear which measurement device should have priority or why. So the argument is specious because subjective and objective aren't the only options?

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  5. That's not what is going on. There is no sense in which one inch is right and 2.54 cm is wrong. They are just different. No one says, the length is one. If you say that there is no sense in which the perception is right and the reality are wrong, they are just different, then you still have an appearance/reality distinction.

    Or, as Descartes might have put it, there is a difference between formal reality and objective reality.

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  6. Though I am not sure if Lawrence Hass is tapping into this aspect, the way I understand his claim, from an embodied Merleau-Ponty position, is through the lens of cultural practice. The act of lining up a ruler and saying it is one inch long, or 2.54 cm long, is purely a learnt, cultural act. This means it is an act contained within a particular time, culture etc. The key to Merleau-Ponty's phenomenology is that once these practices are acquired, they change and influence the very structure and nature of perception. So, we can not say that the ruler measurement is less subjective than how we see the Muller-Lyer illusion. Both reveal the perceptual structures we have.

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  7. Nik,

    I am not sure that this is what Hass is up to either, but it is an interesting proposal. Thanks. So, one might say that ruler measurement is just as subjective as perception.

    Still, the subjectivity that seems to be relevant here does not involve rulers. To get this, note that, for perceiver A the upper line looks longer than the lower line. No rulers needed for this. Now, perceiver/scientist B can come along and determine (perhaps with a ruler) that the lines are of the same length. So, perceiver A's perception might not be contaminated at all, so to speak, with the cultural practice of line measurement, and so forth, that B has.

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  8. I think M-P would be happy saying there is a difference between A and B, and that one involves a practice learnt from the world around us. The concern that he wants to raise is: in the case of the scientist B, what she is doing is not accessing some fundamental objective part of the world as distinct from the cultural, bodily practices. It is only the cultural, not the objective.

    This is M-P's phenomenological approach, in that everything we do is only knowable from an embodied position, a historical and cultural perspective. So if we claim that seeing the Muller-Lyer illusion is due to some biological aspect of our being, while using the ruler is a cultural act, neither of these are privileged in an objective "world out there" sense. Both tell us about our nature of where and who we are.

    Due to bodily perspective being primary for all knowledge, phenomenal experience becomes the most fundamental way to understand the world. Why? Because perspective only comes together at the moment of perception. It is the act of perception, with all its flaws (i.e. the illusions and mirages), that is the object of any inquiry about "the world" and not the external world itself which we only have access through embodied perspective.

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