In any field of science, knowledge must be organized into systems in order that the student of any particular problem may have ready at hand the knowledge of facts, generic concepts and principles that bear upon his problem. If all the knowledge in a field cannot be organized into a single system, it is necessary that the several systems be interrelated as far as is possible [Cohen, 115, 106-14].
In geography, knowledge is organized into systems in two quite different ways. We may divide the phenomena of areal differentiation into major groups each consisting of closely related phenomena, and thus develop specialized branches of the whole field of geography. These include, then, physical geography, economic geography--which may be further subdivided into agricultural geography, the geography of mining, of manufacturing, etc.-- political geography, and what might be termed sociological geography. It is, of course, an error to include historical geography in this group, for that is, in itself, a complete geography of any past period (cf. Section VI C).
On the other hand all geographical knowledge, including that in each of its specialized branches, may be organized according to the two different points of view required in studying the areal differentiation of the world: the view of any particular variable phenomenon in the relations of its differentiation to that of other variables over the world, and the view of the total character of all the variables within the area (See Supplementary Note 49).
The organization of geographic knowledge in terms of the individual phenomena studied is called "general geography" by European geographers, or "systematic geography" in this country. The organization according to areas is most commonly referred to as "regional geography." (The use of the term "special geography" for this form of organization is fortunately no longer common. In German geography the usual term is "Länderkunde.") These two different methods of dividing the field of geography cannot be combined on a single plane. Each of the specialized branches of geography is represented in both systematic and regional geography--in systematic geography by separate studies of single elements or element-complexes, in regional geography by a part of a regional study, limited to a particular group of related aspects. Thus the study of the element-complexes of concern to agriculture--complexes of land-use and of natural conditions, etc.--is a study in regional agricultural geography--e.g., Colby's study of the raisin production of south central California [337].
It is clear that other groupings of geographic features into special fields are possible, as in the geography of settlements (Siedlungsgeographie) or in urban geography. The geography of any particular city is clearly a special form of regional geography, whereas the studies of individual urban features as found repeated in many cities would be included in systematic geography. Further, because a city, like a farm, represents an actual element-complex that may be considered as a distinct unit, systematic urban geography may study the cities of the world, or any part of it, in terms of their differential character in relation to other geographic differences.
That no place is provided for "mathematical geography" and cartography may require a word of explanation. In climatology we are concerned with areal differences that result from the relation of the planet earth to the sun, but for the facts of that relationship we depend upon astronomy. Likewise, the study of the exact shape and measurement of the earth presents problems to astronomy and geodesy (see Sec. III B). The problem of projecting a sphere, or the geoid, on a plane surface, the science of projections, is essentially a problem in applied mathematics, which is of no less concern to astronomy than to geography. Consequently, the chapter on "mathematical geography" that often forms the introductory chapter of a geography text, commonly consists, as Hettner has noted [111, 274 f.], almost entirely of astronomical and other non-geographical material. Though such an arrangement may seem logical, it may be questioned whether the most effective method of introducing students to the field of geography is to begin with detailed studies from other fields--as though a text in biology should begin with a detailed study in chemistry, leading up to biochemistry. Finally, cartography, which is a technique rather than a science, is a form of knowledge of service in many sciences. Because it is more essential to geography than in any other science, and has been developed to highest extent in geography (see Sec. VIII D), it is both natural and reasonable that it should be most closely associated with our science, but it is no more a branch of geography, logically speaking, than is statistics a branch of economics.
Geography, as the study of the world, necessarily includes a large number of different aspects that are, or may be, represented by specialized fields. Nevertheless it is a well- known fact, which can be tested by any random observation of the literature, that by far the greater part of the work in the field--whether in systematic or regional geography--consists of either physical (natural) or economic geography. Urban geography theoretically overlaps beyond these special fields, in actual practice consists of but little more. The fairly sizable literature in political geography is as yet of minor importance and of sociological geography we have almost none. This situation might be regarded as a natural result of the particular manner in which geography has developed in the past century, or it might be suggested that geographers have commenced with the more obvious and simpler problems, leaving the more complex ones for later study. Overlooking the dubious psychological assumption involved in the latter explanation, there are reasons of much more permanent validity.
In the study of the areal differentiation of the world, the interest of geography in each of the many features which contribute to that differentiation is in proportion to its relation to the total. Each of the natural features varies notably in different parts, and its variations are
significantly related to those of some other natural features and many cultural features. In general, the marked differences in the natural environment of different parts of the world, and the partial dependence of most cultural features on the natural environment, is adequate demonstration of the axiom that physical geography is of fundamental importance (See Supplementary Note 50) in geography as a whole.
The justification for the notable concentration of geographic work of recent decades on economic geography is not so obvious. To many students this may appear to represent an emphasis on studies of presumably practical value that appears foreign to the spirit of science. Undoubtedly, much of the work in this field is stimulated by such extraneous considerations; if it is definitely designed to serve practical purposes--as in land-use surveys, etc.--it finds its justification as an applied form of geography. Undoubtedly any science receives stimulating reactions from the work of those who endeavor to apply its knowledge and methods to particular problems, but there is an essential incompatibility between the two forms of science, theoretical and applied. The latter is defined and determined in character by the nature of the problem which it has to study in any particular case. A particular, complex problem will not fit into any theoretical branch of science, but calls for all forms of knowledge and techniques applicable to it. Even if the work be divided among a group of different scientists, the division can hardly follow, even in principle, the divisions of theoretical science (See Supplementary Note 51).
Further, it may be claimed that much of the interest in economic geography represents primarily an interest in economic phenomena, which are studied more or less in their geographical aspects. Granted that this may be true for many studies--notably those concerned with the world distribution of certain products, or with the economic situation of particular countries, even though studied in terms of a "geographic basis"--there remain, nevertheless, fundamental reasons that require all the parts of geography concerned with human phenomena to recognize economic geography as of fundamental importance.
In our examination of a long list of cultural features (see Sec. X F), we found that the cultural features whose differences in different areas were of the greatest geographic significance--i.e., in terms of their relation to other areal differences, both natural and cultural--were for the most part economic features. (They do not by any means include all economic features, since many of these are of very little geographical significance, though they may be of great economic significance.) Consequently geographers are justified in regarding human, or cultural geography very largely in terms of economic geography. Furthermore, since economic geography requires detailed consideration of the natural features to which economic phenomena are related, a regional study in economic geography constitutes the greater part of a full study in regional geography. To put it simply, most people live where they live--rather than move elsewhere or die--not because they like the climate, the politics or the customs, but because they are able there to make a living; the manner in which they make a living, and consequently the manner in which they live in general, are, in large part, determined by the interrelation of economic and natural features which it is the function of economic geography to study [cf. Schmidt, 7, 162-200].
On the same basis we justified the major emphasis in geography on agricultural (in the sense of land-use) geography. The features of urban areas are, to a much greater extent, undifferentiated in different areas. Needless to say, however, this does not mean that the regional geography of even a predominantly rural area is complete if the cities are omitted or barely mentioned; the relations between the agricultural areas and the cities is of essential importance in understanding the character of the area.
On the other hand, in at least two major parts of the world--namely the two parts of greatest concern to European and American geographers--areal differentiation is represented in great part by the differential development, in intensity and in character, of urban development. For these areas m particular, geography is greatly concerned with the geography of manufacturing, upon which the urban development is largely based, and with the study of the cities themselves as the most extraordinary features of areas that man has produced.
The conclusion that physical and economic geography make up the major portion of geography as a whole does not for a moment suggest that the other parts are to be ignored. In the first place there are many features of economic geography that cannot be correctly interpreted without an understanding of their relation to areal differences in culture, in the narrower sense of the word, and in political organization. These are therefore geographically significant features, and, in order that their relationships to others may be known with certainty, they need also to be studied systematically.
That major areal differences in culture may be of great importance in relation to other geographic features is familiar to anyone who has traveled in eastern Europe, or has crossed the Rio Grande, or been to mid-latitude South America, not to mention the vast differences to be observed in areas of Sino-Japanese and Indian culture. The differences of culture of a secondary order, however, appear to have but minor effect. A careful study of the maps of crop production in Europe reveals the importance of a boundary running from the North Sea to the Alps, east of which rye and potatoes are far more important than in areas of similar natural conditions to the west; the line follows approximately the Franco- Germanic cultural (not national) boundary. The difference mentioned, however, is clearly minor. Likewise, the more obvious differences in architecture, in customs, etc., can hardly be regarded as geographic differences of the first magnitude. Consequently, a detailed systematic study of the geography of peoples, whatever its value for other purposes, would appear to offer a minor contribution to geography as a whole.
On the other hand, just as the importance of the geography of mining is found, not in itself, but in its significant relation to the far more important geography of manufacturing, so the geography of peoples, even in great detail, is of major concern to the geography of states. While the study of states--in the sense of independent political units--is perhaps but a lesser part of political science, the geography of states (See Supplementary Note 52) constitutes the major part of political geography. This conclusion results from a particular characteristic of the state that is often lost sight of in the discussions of the place and function of political geography as a part of the field as a whole.
As a social organization any political form, whether a state, a government, or other commonalty, is a feature that differs, to be sure, in different parts of the world, but the differences have but little relation to those of other features. The proposition that the mountainous islands of the Hellenic archipelago constituted the necessary background for the development of the democracies of the Greek city-states is a proposition in the geographic aspects of political science; it would not be suggested by a systematic study in the geography of mountainous islands or of democracies. If the "mother of parliaments" is located on a fair-sized island, close to, but separated from the mainland, an island of certain conditions of climate, relief and soil, her daughters appear to thrive in areas of radically different natural environment and of very different economic geography. In the study of political organizations considered from this point of view, geography, as Penck suggests, may have little place other than to offer supplemental suggestions to the political scientist [163, 51 f.].
On the other hand, the geographer has a direct interest in the state as a division of the earth surface. The fact that that division, as Penck insists, is made by man and is not inherent in the nature of the earth, is immaterial to us, since we have found that any division of the earth can only be made by man. Neither can we accept his description of the earth surface of a state as "merely the stage of man's (political) action, to be sure a stage that influences it"; such a description represents only the political scientist's point of view of the state-area. For geography, the state is an area in which certain conditions are universally true in contrast with those of other state-areas. It is, therefore, an area of homogeneity in certain very important respects, and so forms the simplest as well as the most definitely delimited of all geographic phenomena. Further, as we observed in our examination of the concept of regions as units, the state is the only area larger than a city which is organized as a functioning areal unit Whole (Sec. IX F). Unlike the abstract concept of the "region," the state area is, in many respects, a concrete unitary object; it is a piece of the earth's surface sharply defined and separated from other pieces, with which its relations are, in many respects, the relations between whole units. Like other concrete objects, the state-area has size, form, and structure. Indeed, it is in the consideration of the structure of a state that our concept of regions becomes of practical rather than merely academic importance.
To many geographers, particularly in this country, the concept of the state as an areal unit may appear remote from geography, not merely because it can be observed in the visible landscape only with difficulty, if at all, but also because of a wide-spread impression that man's political structure is something extraneous, essential neither to the earth nor to man. On the contrary, as Schlüter has noted, "the state (in the widest sense) is no younger than man, but rather older. Man could not become a human being without the protection of an association which contains the seed of the state. Man has been from the beginning the zoon politikon of Aristotle" [134, 410]. For man, as a political animal, it has been just as natural to create a state as a farm or a city [cf. Vogel, 271, 5], and the state which he creates, as East concludes, "whatever else it is . . . is additionally and inevitably a geographical expression and as such forms part of the subject matter of geographical science" [199, 270; cf. also 216, 802-4].
Since there has been considerable controversy over the relation of this part of geography to the field as a whole, we may examine briefly the significance of the state-area as a subject of geographic study. The notable differences in size and form of the state-areas of the world is one of the most obvious facts of areal differentiation of the earth surface. It is, therefore, one of the characteristics of the world which needs to be understood in a subject devoted to the study of the differences in different parts of the world. That it could be considered as a fact of minor importance is refuted by the reality of the power of states in controlling not only the political, but also the economic life within their areas. Finally, this important fact of areal differentiation is significant in geography if it is significantly related to other features of areal differentiation.
It is of course false to conceive of the division of any part of the earth into state-areas as "natural"--i.e., as determined by the natural conditions; since the phenomenon itself is cultural, neither the state nor any of its elements, such as boundaries, can be natural [357]. But one cannot compare the political map of Europe or Asia with the corresponding relief map without realizing that there are close relations between the two forms of differentiation. Even where the political map may seem highly arbitrary, as in South America, a consideration of the map of population density, and then of the maps of natural elements that explain it, will show that it is only the outer boundaries that are arbitrary; the essential division into states is very significantly related to the natural geography of the continent.
The state-areas differ not only in the obvious features of size, form, and locational relations to each other but also in their internal structures. The differences in structure in different state-areas is directly related to the regional structure of the area in terms of physical, economic, and ethnological geography.
In the reverse direction, the economic differentiation of the world with which we are concerned in economic geography is notably affected by the efforts of all states--more marked in some than in others, but present in all--to organize all the cultural features of its area into a more or less homogeneous and closed unit.