ETP entailed some amazing claims. First, it claimed that what a person perceives is never an object as it is “in itself” but rather an “appearance” of the object, as it appears to the perceiving mind. David Hume called these “appearances“ impressions, but they have subsequently acquired different appellations by philosophers working in the empiricist tradition, such as “sense data” or “qualia” or “sensations” or “sensabilia” or “precepts,” or “ideas.” It is such sensed data or impressions that were said to be the immediate object of perception, what is directly “given” to us in our experience. Hume called faint copies of these impressions, “ideas.” Thus the only difference between impressions and ideas was in degree (“force and vivacity”) not in kind. All our empirical knowledge was said to be built up by means of impressions, and an empirical knowledge claim was considered valid only if it could be traced back to the original impressions that were its foundation.
The arguments used to support this thesis came to be known as the “argument from illusion” and the “argument from hallucination.” For example, here is Hume espousing one example of the argument (the “double vision” argument): “When we press one eye with a finger, we immediately perceive all the objects to become double, and one half of them to be remov’d from their common and natural position. But as we do not attribute a continu’d existence to both these perceptions, and as they are both of the same nature, we clearly perceive, that all our perceptions are dependent on our organs, and the dispositions of our nerves and animal spirits.”
Here is a contemporary philosopher, Hilary Putnam, criticizing ETP, “The Seventeenth-Century Picture”: “If there is something you immediately perceive, the view runs, it must have all the properties it seems to have…. A physical thing might have one property and seem to have another; but how could the sense data that are produced in me by that physical thing seem to have one property and really have another? The sense datum ‘is’ the appearance. …Appearances are one set of objects and external things are another set of objects, and how could appearances have properties other than the ones they ‘appear’ to have?”
After 400 years or so of analyses of ETP, suffice it to say that it has been firmly established that every sense, hearing, sight, smell, taste, touch, is subject to illusion. Take, for example, a simple case: under appropriate lighting conditions, a white wall may look, say yellow. Then it assumed that there must be something that actually has the property of being yellow, and that something is the appearance or sense datum. Insofar as the mental, subjective nature of that datum is the same as when the “real” wall is being perceived, what we immediately perceive in all cases of perception must be sense data, and not the “actual” physical thing.
Arthur Schopenhauer, the German philosopher, would equate the “veil of appearance” with the Hindu notion of the “veil of Maya.” Our ordinary consciousness of the external world is said to be illusion, whereas the “true” reality is Brahmin or “pure consciousness.” The gist of the matter, it seems, is that when you create a distinction between “appearance” and “reality” you inevitably run into trouble. Then it seems that the appearance of reality becomes the reality of the appearance, and the external world gets lost in process. This is so, for what we perceive directly are sensations, from which we infer the existence of an external world. But the world in itself, independent of experience, may never be perceived. Sensations lead only to other sensations, not to mind independent material objects.
The consequences of ETP seem to be absurd, for it appears to belie our practice rather than explain it. We assume there is an external world and that communication is possible. ETP locks us in a private, subjective world of our own sense data. Idealism and Solipsism seem inevitable.
Nowadays, or so I’m told, the majority of professional philosophers have jettisoned ETP. The notion of “Direct Realism” has become the vogue, along with a closet kind of Materialism, or an equally absurd Relativism. In the hundreds of years of enthrallment with ETP, in the attempt to get beyond it, new theories of perception and new philosophical viewpoints have evolved. Thus understanding the cogency of ETP is essential to understanding the nature of contemporary philosophy. Just like life, we may learn by our mistakes as we seek the open road.
Puzzle
1. There is a very famous series of numbers, such that if you take the sum of the series of squares of its first N terms, the result is equal to the product of its Nth term and the (N + 1)th term. Can you find he sum of the squares of say, its fist seven terms? Here is a hint: 1^2 + 1^2 +…..+N^2 = N(N + 1).
Answer to last week’s puzzle
Max (x, y) = (x + y + abs (x –y))/2
