A scientific approach to meaning widely used in the past is the traditional philosophical theory of "the mental image." This approach assumes that the real meaning of a word can be equated in some manner with the mental image associated with the symbol. It has the advantage of seeming to simplify the study of meaning, for it is far easier to maneuver and classify the mental images than to sort and arrange the referents to which such word symbols might refer. In the long run, however, this"mental image” approach has proved relatively sterile, for it does not answer some of the basic questions about meaning. For example, to say that triangle means the mental image of an ideal triangle is not really satisfactory, for many shapes can be labeled triangles, and a mental image in the traditional sense cannot be an image of all these---certainly not all at the same time. The more abstract or generic the meaning of a term, the more difficult it is to produce a mental image that adequately reflects thc function of this symbol.

The behaviorist approach to meaning in terms of stimulus and response, using Pavlovian types of stimulus-response situations, corrected some extravagant excesses in the traditional philosophical orientation. Psychologists insisted that no one could really test the meaning of mental images, since no one could get inside another's brain to see what went on there. One could always describe what went on in his own thinking, but such individual descriptions seemed too subjective to be valid for objective experimentation or measurement. Moreover, though the measuring of the responses of animals under closely controlled conditions was not too difficult, it was impossible to subject human beings to the same types of controls in order to get objective measurements of response to word stimuli. Furthermore, it proved hopeless to determine all the stimuli that might enter into any one person's use of a particular word as a response. As a result, behaviorists began to talk about "behavioral dispositions," a theory constructed on the basis of simpler types of animal responses, which were presumed to underlie human responses. These projections, however, have proved to fall far short of an adequate explanation of linguistic phenomena. Nevertheless, thorough psychological investigations of meaning have done much both to sweep aside previous mentalistic views and to focus attention on certain essential elements in communication, namely, the stimuli and the responses involved in both speaker and hearer.

A somewhat different approach to language and meaning characterizes the work of the symbolic logicians, also called logical analysts or linguistic analysts, who have been dissatisfied with traditional logic, on the ground that it merely prescribes how people ought to think. Furthermore, they did not see much future in following the psychologists in describing how people presumably do think. What seemed more fruitful from their standpoint was a thorough investigation of language, either as the tool by which people manipulate their thoughts or as the system which, as closely as any other, reflects their thinking. Accordingly, symbolic logicians scrutinized language carefully and exposed many problems passed over by others, or merely taken for granted as a part of logic itself.

Some symbolic logicians have divided their study of meaning into three main parts, usually called (1) semantics, (2) syntactics, and (3) pragmatics. For the symbolic logicians, semantics deals with the relationship of signs (or symbols) to referents, corresponding roughly to what people usually think of as the meaning of words. However, this meaning is regarded in a distinct way, for the referential meaning of any symbol is defined in terms of classes of referents. The referents themselves are infinite in variety, but the symbols are "handles" for dealing with groupings of similar objects and events. This process of classification is of course essential, for "unless one categorizes, that is, classifies, there is no basis for forming any judgments as to expectancies, for objects and events are in themselves unique. To handle them, we must classify them" (Roger Brown, 1958, p. 224).

This classification takes place in two principal ways: (1) by segmentation and (2) by distinguishing shared qualities. In no two symbolic systems, that is, in no two languages, is this classification identical. For example, we segment the color spectrum in English into eleven basic color words, but in West Africa a number of languages make only three fundamental color distinctions: red, white, and black. In the Parimiteri dialect of Waica, spoken in northern Brazil, the people seem to get along quite well with four basic color words, with the following groupings:

(1) waki , "red, reddish purple, yellow, and orange", (2) ushi, "dark blue. dark purple, black, deep red, and brown". (3) krokehe,"green", and (4) au. "white, clean". The Tarahumara in northern Mexico have five basic color words, including one term, siyonomi, which covers both green and blue.

The distinguishing of shared qualities may result in very complicated classifications. For example, the Hanunóo distinguish more than 1,800 different plants which grow in their region of Mindoro, in the Philippines. Such a classification differs appreciably from the way in which botanists classify these same plants; in fact, botanists classify these plants into somewhat less than 1.300 species (Conklin, 1962).

While semantics deals with the relationship of symbols to referents, syntactics is concerned with the relationship of symbol to symbol; for the meaning of expressions is not to bc found merely in adding up symbols, but also in determining their arrangements, including order and hierarchical structuring. For example, the constituents black and bird, when occurring in juxtaposition, may have two quite different meanings. In one instance we say blackbird, with the primary stress on the first element,and in the second, black bird, with the primary stress on the second. But there are clear differences of meaning, for not all black birds are blackbirds. Similarly, a greenhouse is not a green house, and the fat major's wife may mean that either the major or the wife is fat. But symbolic logicians go far beyond such problems of obvious ambiguity in attempting to describe carefully all the basic relationships of words.