Clarifying Ostensive Definitions by Logical Possibility of Inverted Color Perceptions

1 The View-point of Logical Empiricism on Ostensive Definition

In the paper "Meaning and Verification", M. Schlick told us "To understand meaning, there is no way in which ostensive definitions needn't be involved; that is to say, to understand meaning, 'experience' and 'possibility of verification' had to be involved"; "By the ostensive definitions, verifiability is hence related to 'experience' in the first sense (namely sense?data?? the author)". (Translated from Chinese[1]).

What is sense datum? G. E. Moore proposed it when he analyzed daily language [2]. Moore was not satisfied with that many philosophers since J. Locke considered colors, sounds, odors and the like as man's sensations. His reason is that, for example, when a man looks at an object, he can say that he has some color perceptions in his mind, but cannot say he has some colors in his mind. So, colors, sounds, odors and the like should be considered as "sense?data" instead of sensations. The "sense datum" here means some property of objects, even though Moore didn't think that the property was objectively existing. Yet, later, some philosophers used "sense-data" to mean the given and the raw experience [3] so that sensations and sense data were confused again. Any way, according the usage of "sense-data" by most logical empiricists and some other philosophers, a sense?datum is what sense organ directly perceived, its relation to a sensation is alike the relation between action and reaction in physics.

It may be said that logical empiricism is based on its view on the ostensive definitions. An ostensive definition is made by man's pointing something and saying something such as "This color is red", from which the relationship between a sensation and a word such as "red" is set up. However, This definition needs an important premise that the sensations obtained by different persons corresponding to the same words, such as "red", "green", "sour", and "salt", should be identical. Yet, it is at this point that there is a fatal problem with logical empiricism. For example, Schlick affirmed that the raw experience was neutral and without any owner and hence identical to all people. It was an important step that Mach and Wittgenstein found the raw experience was not of the first person; only after this step was taken, many profound philosophical problems could be clarified [1].

Although many materialists are not satisfied with the conclusions of logical empiricism, they have no different opinion about the view of logical empiricism on ostensive definitions because they believe that a sensation reflects a property of objects and there is a one-to-one relation between the sensations and the properties. As to that ostensive definitions are made with the sensations or with the properties, this is of no importance to them. They still more have no doubt about the identity between sensations of different people. What is critical in this paper is to prove that the identity between sensations or experiences of different people cannot be logically proved. And it is possible that different people with the same language have different even inverted sensations; and hence, the view of logical empiricism on the ostensive definitions is logically wrong.

2 The Logical Possibility of Inverted Color Perceptions

To explain the logical possibility of inconsistency between perceptions of different people and to clarify the essence of ostensive definitions, we first introduce the logical possibility of inverted color perceptions (LPICP).

Corresponding two different colors, such as red and green, Tom has two color perceptions a and b in order in his mind; whereas John has b and a in order. The two color perceptions and all those between the two that two persons have are all inverted, or systematically inverted; this is called the inverted color perceptions. The logical possibility of inverted color perceptions was mentioned by J. Locke many years ago[4]; nevertheless, Locke didn't pay much attention to it because he thought that this possibility couldn't improve our knowledge or modify our life. It seems that Locke disliked this possibility because it contradicted with his basic idea: what "colors", "sounds", and "odors" indicate are only perceptions in man's mind. Only recently, some philosophers in the Northern America were conscious of the importance of the logical possibility of inverted color perceptions[5,6].

American philosophers express the inverted color perceptions as "the inverted spectra". The action of the logical possibility of the inverted spectra (LPIS) is destructive there. It was raised at first to falsify functionalism, a Revised Version of behaviorism, in psychological philosophy [6]. About how to define mental states, there are two opposite schools: functionalism and physicism. Functionalism holds that every mental state may be functionally defined or be defined by means of its typical causal connections to sensory stimulation and behaviors; whereas physicism affirms that every mental state may be physically defined. The opposition faction of functionalism claims that LPIS shows that the type?identity of mental states does not exist when different people have the same language and behaviors; so, functionalism is impossibly correct. At the same time, the other faction replies that the same censure can also be applied to physicism. To resolve the problems caused by LPIS, the philosophers proposed various remedial methods; but, the problems are still in great confusion. Someone hence holds that even if the inverted spectra are logically possible, we had better neglects its existence to prevent our minds from being confused by it and to avoid falling into the mud of skepticism [6,7].

The author recognized the logical possibility of inverted spectra when he set up a mathematical model of color vision. This model shows that which perception a color causes depends on which color-visual cell in convex receives the color signal from the retina. The corresponding relations between colors signals and color?visual cells for two persons are probably systematically different but may be fully equivalent. At the beginning, the author thought that LPICP was his own discovery, and obtained a series of optimistic conclusions. From my view?point, it is LPICP that will bring the critical resolutions of psychological philosophy and ontology. American philosophers are cornered because, first, they want to define mental states with daily language, which is logically impossible; second, they confuse colors and color perceptions, which is shown by their usage of "the inverted spectra". Actually, colors and spectra cannot be inverted; what can be inverted are only color perceptions in men's mind.

For convenient discussion, we restate an easily understood proof of LPICP. Assume that two children innately have color perceptions that are inverted to each other corresponding to red and green colors. Obviously, they cannot know the difference between their color perceptions when they are born. Lately, their parents or grandmothers can only point to grass or flowers instead of one's perceptions to teach them what "red" and "green" mean. Hence, even if the two children have the different color perceptions, they must accept the adult's definitions of "red" and "green" in the same way so that two children will identically call red and green colors after they grow up. Analogously, each of us probably has totally different color perceptions from other's.

3 The Philosophical Conclusions Brought by LPICP

The most important significance of LPICP is that it can reveal the essence of ostensive definitions. We can find that, from the above example of how the two children accept the definitions of "red" and "green", ostensive definitions are made with

objective things instead of man's perceptions; what "red" indicates can only be some property commonly shared by blood, red flags and the like; what "green" indicates can only be some property commonly shared by grass, leaves and the like. Natural science tells us that these properties are the abilities of reflecting natural lights of objects. First, they are different from perceptions and independent of our bodies. Second, we commonly face them. To such properties, we can only consider they are objectively existing.

In daily life, almost everyone wrongly think that what "red" and "green" and the like mean are something (sense-data) on surfaces of objects and are directly perceived by our sense organs. The psychological misconception can be explained with the

following case: when a man points to a yellow desk and says "this is yellow", he thinks that what he points to is something that seems on the surface of the desk and is directly perceived. Actually, what he directly perceives are only the image of the desk and the color perception in his mind. What we point to and what we directly perceive are not identical though we generally think that they are identical, which is just the profound mystery of ontology.

It is easy to find that the usage of "sense data" by the Western philosophers is full of contradictions. On one hand, they use "sense-data" to indicate the given, the raw experience; even if they are not equivalent to sensations, at least they have one?to?one relations with perceptions. On the other hand, they forcibly use it to indicate what "colors", "sounds", "odors" and the like. Since the different person may has the different perception corresponding to the same word such as "red", the above usage is logically unfeasible.

In fact, even if we use the criterion of meaning of logical empiricism, it also cannot be verified that sense?datum is neutral and identical to all people because we can ask that when it is supposed so or not so, how different are the sense?data you will obtain? A possible answer is that if it is not so, then different people wouldn't use language in the same way. However, this view is thoroughly wrong.

Since many years ago, many of the Western philosophers have been taking delight in talking about that we cannot go beyond perceptions and experiences to talk about external objects themselves; what we can know is only phenomenal word and objects themselves are impossibly understood. Now we see that daily language always directly point to objective things themselves or the external word over perceptions and experiences. The author believes what Wittgenstein said that the limitation of language means the limitation of my world?[7]. From my viewpoint, it is because of language as a tool that one can overstep perceptions and experiences to recognize the external world. So, it is perceptions, experiences, and phenomena instead of the external world that cannot be talked about in daily language; it is the perceptions in others' mind instead of the external objects that are unknowable.

References

[1] Schlick,M.: Meaning and Verification, in Logical Empiricism, Ed. by Hong Qian, Commercial Press, Shanghai,1982, 37-68

[2]Moore,G.E.: The introduction to Sense data, in Perception and the External World, Macmillan Press, New York, 1965, 97-107

[3] Price, H.H.: The given, in Perception and the External World, Macmillan Press, New York, 1965, 108-115

[4] Locke, J.: Treatise concerning Human Understanding, Vol.2, Ch. 32, Sec. 15.

[5] Lu, Chen-Guang: The debate on the inverted spectrum in U.S.A., The developments of Philosophy, No.8(1989),7-17

[6] Shoemaker, S.: The inverted spectrum, J. of Philosophy, 79(1982),375-381

[7] Wittgrnstein, L.: Tractus Logico philosophicus, 1922, London