¹ See Aron, Raymond, Peace and War (New York 1967)Google Scholar; Organski, A.F.K., World Politics (New York 1968)Google Scholar; Morgenthau, Hans J., Politics Among Nations: The Struggle for Power and Peace (New York 1964)Google Scholar; Rosecrance, Richard N., Action and Reaction in World Politics: International Systems in Perspective (Boston 1963)Google Scholar; Rummel, R. J., “Dimensions of Dyadic War, 1820–1952,” Journal of Conflict Resolution, X (March 1966), 65–73CrossRefGoogle Scholar; Tanter, Raymond, “Dimensions of Conflict Behavior Within and Between Nations, 1958–1960,” Journal of Conflict Resolution, X (March 1966), 41–64CrossRefGoogle Scholar; Singer, J. David, “Capability Distribution and the Preservation of Peace in The Major Power Sub-System, 1816–1965” (Paper prepared for delivery at the 66th Annual Meeting of the American Political Science Association, Los Angeles, September 1970)Google Scholar; and Wright, Quincy, A Study of War (Chicago 1942).Google Scholar We are particularly indebted to Professor Organski for a treatment of the concepts that provided the basis for our investigations.

² Sprout, Harold and Sprout, Margaret, Foundations of International Politics (Princeton 1962).Google Scholar

³ In the shorter-run, during a crisis of a few days' or weeks' duration, for example, the numbers of people or the broad levels of their knowledge will not vary appreciably. In such instances, perceptions, values, preferences, goals, expectations and decisions may be the crucial variables, with dimensions of population, level of technology, and so forth, serving as constraining parameters. But in the longer-run, over years and decades, the numbers of people, their rate of increase, their level of technology, their rate of technological development, and the availability of natural resources in the environment, all seem to be powerful shaping and constraining influences.

⁴ von Bertalanffy, Ludwig, General Systems Theory (New York 1968)Google Scholar; Miller, James G., “Living Systems: Basic Concepts,” Behavioral Science, X (October 1965), 337–79CrossRefGoogle Scholar; and Miller, James G., “Living Systems: Cross Level Hypotheses,” Behavioral Science, X (October 1965), 380–411.CrossRefGoogle Scholar

⁵ Wiener, Norbert, Cybernetics (New York 1948)Google ScholarPubMed, and The Human Use of Human Beings (New York 1956).Google Scholar

⁶ Service, Elman R., Primitive Social Organization (New York 1962)Google Scholar; and Farb, Peter, Man's Rise to Civilization as Shown by the Indians of North America (New York 1968).Google Scholar

⁷ See especially Organski (fn. 1), and Sprout and Sprout (fn. 2).

⁸ Howard, Alan and Scott, Robert A., “A Proposed Framework for the Analysis of Stress in the Human Organism,” Behavioral Science, X (April 1965).Google Scholar

⁹ Tanter, Raymond and Midlarsky, Manus, “A Theory of Revolution,” Journal of Conflict Resolution, XI (September 1967)Google Scholar; Davies, James C., “Toward a Theory of Revolution,” American Sociological Review, XXVII (February 1962).Google Scholar

¹⁰ Ehrlich, Paul R. and Ehrlich, Anne H., Population, Resources, Environment (San Francisco 1970), 54–55Google Scholar, 82; see also Odum, Howard T., “Energetics of World Food Production,” The World Food Problem, A Report to the President's Science Advisory Committee, III, Report of the Panel on the World Food Supply (Washington 1967)Google Scholar; Resources and Man, Committee on Resources and Man, National Academy of Sciences, National Research Council (San Francisco 1969).Google Scholar

¹¹ Some societies obviously possess and “demand” considerably more than the irreducible minimum. Often, within a single society, some sectors of the population are affluent and others exist on the borderline of subsistence. In general, the societies with more affluence tend to be those which through one means or another, have access to relatively more resources and possess higher specialized capabilities. Useful suggestions for the analysis of complex relations are provided in Ashbv, W. Ross, “Constraint Analysis of Many-Dimensional Relations,” in General Systems, Yearbook of the Society for General Systems Research, IX (Michigan 1964).Google Scholar

¹² Sprout and Sprout (fn. 2), 8.

¹³ The consumption of resources (according to the First Law of Thermodynamics) does not mean the destruction of energy, but (according to the Second Law of Thermodynamics) usable energy is degraded with each transfer from more usable forms to a less usable form. New applications of technology (the breeder reactor, for example, or nuclear fusion) may provide more efficient uses of primary energy. But such advances are likely to involve large amounts and a considerable range of other resources (such as minerals, fibers and so forth) in the construction of plants, machinery and auxiliary equipment and by way of raw materials for the production of artifacts. A more advanced technology is likely to be more efficient than a less advanced technology, that is, it is likely to produce more useable power per unit of input. However, the more advanced and efficient a given technology turns out to be, the greater is likely to be the variety and instances of the uses to which it is put, and consequently, the amount (as well as the range) of resources is likely to increase over-all.

¹⁴ “Effects of Population Growth on Natural Resources and the Environment,” Hearings, Subcommittee of Committee on Government Operations, House of Representatives, 91st Congress, 1st Session, September 15–16, 1969.Google Scholar

¹⁵ We need not assume a fixed resource base to appreciate the full implications of these relationships. The interdependence of technology and resources is high. For example, resources may be discovered, or “created,” where they were not known to exist. Or they may be acquired through trade, conquest, or other means. As long as the flow of resources is not severely impeded, or not perceived to be impeded, then the technology-resource-population relationship poses fewer problems for a society than otherwise. For elaboration of these points see especially Resources and Man by the Committee on Resources of Man and the Division of Earth Sciences, National Academy of Sciences, National Research Council, 1968.Google Scholar

¹⁶ Over the course of human pre-history and history the broad advancement of knowledge and skills has tended to be exponential (extremely slow for many centuries, increasingly rapid in more recent times). However, at any given period, certain societies have tended to advance more rapidly than others. Often, a comparatively backward country, such as Japan around 1870, has displayed very rapid growth partly as a result of diffusion from more technologically advanced countries.

¹⁷ Howard and Scott (fn. 8).

¹⁸ Such an interdependency of alliance commitments and obligations had a great deal to do with expanding what was a local conflict during the summer of 1914 into a major war. And the Cuban Missile Crisis of 1962 defined in a number of ways the limits beyond which neither Castro nor the USSR could move without risk of great cost to one or the other, or both.

¹⁹ Again, what the correlates of lateral pressure are is subject to investigation. In contrast to “demands,” explicit indicators of lateral pressure are readily available. See the Research Note below.

²⁰ Moore, Barrington Jr., Social Origins of Dictatorship and Democracy: Lord and Peasant in the Making of the Modern World (Boston 1967), 40.Google Scholar Moore emphasizes the importance to English institutions of relationships between the landed gentry and emerging commercial elements. Commerce and manufacturing lagged in France, as compared with England, and in consequence “All the main structural variables and historical trends in French society of the ancien régime differed sharply from those in England from the sixteenth through the eighteenth centuries.”

²¹ Thus Britain, as she became more and more a commercial nation, developed merchant shipping capabilities and a powerful navy. These specialized capabilities were critical factors in her achievement of an overseas empire. Russia tended, on the other hand, to expand her interests overland—eastward across Siberia—although she built fleets for Baltic, Black Sea, and Pacific service. See also Toynbee, Arnold J., A Study of History, III (London 1935).Google Scholar

²² In these terms the concept of lateral pressure provides a link between theories of imperialism and colonialism on the one hand, and integration theories, funclionalism, and federalism on the other. Much of the Marxist argument rests on the notions of surplus value and investment of energy outside territorial boundaries. In this context Hobson's interpretation seems as likely a hypothesis as the Leninist. Societies do not necessarily have to expand externally by adopting various modes of domination and conquest. It is conceivable, and possible, for societies to turn inward. By the same token, the mode in which lateral pressure is expressed does not necessarily have to be imperialistic, but could conceivably develop along lines of integration and building of political community. The history of the United States provides (as we note later on) a useful example of the interrelation between expansion, imperialism, and integration. Each of these processes reflects, in the terms described above, different dimensions or manifestations of lateral pressure. For a related discussion see North, Robert C. and Choucri, Nazli, “Population, Technology, and Resources in the Future International System,” Journal of International Affairs, XXV, No. 2 (1971), 224–38.Google Scholar

²³ Such relationships would characterize Rome in the late republican and early imperial phases; Britain after the decline of Spain and again in the nineteenth century, as a consequence of her early initiatives in the industrial revolution; Germany in the late nineteenth and early twentieth centuries; Japan after the Meiji Restoration; the United States beginning a decade or so after the Civil War; and Russia in the late nineteenth century (despite her outmoded political and economic system) and increasingly after the Bolshevik Revolution.

²⁴ Moore (fn. 20).

²⁵ It must be noted, however, that Afghanistan exerts some amount of lateral pressure toward Pakistan, although Pakistan probably exerts more toward Afghanistan. Something similar could probably be said about Bolivia.

²⁶ The full impact of United States' lateral pressure from around 1785 through the latter decades of the nineteenth century is sometimes obscured by the fact that the victims were largely Indian tribes. Hence, it was easy to think of the West as “empty.” The same kind of observation is relevant to Russia's expansion eastward to the Pacific.

²⁷ Different parameter values associated with key variables are expected to yield different characteristic patterns of attributes and behavior. In other words, variation in the strength and relationship of key variables—population, technology resources—explain different modes of external behavior and differences between Sweden in comparison with Great Britain, France, or the United States.

²⁸ Policy-makers in socialist states are likely to have more control over specialized capabilities. But even Soviet and Chinese Communist leaders have been seriously constrained by the vast difficulties associated with the planning and management of developments in a bewildering array of specialized enterprises.

²⁹ The types of individuals, groups, classes, or levels of government instrumental in extending national influence may vary enormously from society to society, and even within the same society through time. Thus, the United States and the Soviet Union both extend their influence in search of raw materials and markets, but the modes and mechanisms are quite different. This is not to suggest that Soviet-American rivalry can be explained only in terms of competition for raw materials.

³⁰ Conceptually one might consider one country's resistance to external penetration as the response to another country's lateral pressure.

³¹ The Korean and Vietnamese Wars; the Middle East Conflict; the Quemoy and Matsu crises; the division of Germany, Korea, and Vietnam into separate states; and the emergence of Communist and anti-Communist satellite systems are only a few of the more obvious examples of contemporary linkages between “colonial” or “client” conflict and arms races, crises, and wars involving two or more major powers.

³² Gladstone, Arthur, “Relationship Orientation and Process Leading Toward War,” Background, VI (Fall 1962), 13–25.CrossRefGoogle Scholar

³³ The objective of our research in the long run is to replace the qualifying terms by numerical probabilities.

³⁴ Boulding, Kenneth E., Conflict and Defense (New York 1962), 25.Google Scholar

³⁵ U.S. Department of State Bulletin (August 29, 1966), 305.Google Scholar

³⁶ Boulding (fn. 34), 35.

³⁷ Hermann, Charles F., Crises in Foreign Policy (Indianapolis and New York 1969)Google Scholar; and Holsti, Ole R., “The 1914 Case,” American Political Science Review, LIX (June 1965), 369–77.Google Scholar

³⁸ Wohlstetter, Albert and Wohlstetter, Roberta, “Controlling the Risks in Cuba,” Adelphi Papers, XVII (London 1965), 19.Google Scholar

³⁹ Richardson, Lewis F., Arms and Insecurity (Chicago 1960).Google Scholar

⁴⁰ It is entirely possible for two (or even three) of these dynamic processes to take place concurrently, but one may be more salient at a given time. These relationships and the broader partial theory upon which they rest need additional clarification and further tightening. This is only a first step toward the development of an empirically verifiable theory of international behavior.

⁴¹ Statistics involve descriptions of, and generalizations about, aggregates. It is extremely difficult, if not impossible, to trace the relationship of the individual to the aggregate.

⁴² See, for example, Allison, Graham T., “Conceptual Models and the Cuban Missile Crisis,” American Political Science Review, LXIII (September 1969), 689–718.CrossRefGoogle Scholar See also York, Herbert, Race to Oblivion: A Participant's View of the Arms Race (New York 1970).Google Scholar

⁴³ Ando, Albert and others, Essays on the Structure of Social Sciences (Cambridge 1963), 1.Google Scholar

⁴⁴ See Choucri, and North, , “The Determinants of International Violence,” Peace Research Society, Papers, Volume XII (Cambridge 1968), 33–63Google Scholar; Choucri, and North, , “Aspects of International Conflict: Military Preparedness, Alliance Commitments, and External Violence,” prepared for delivery at the Western Political Science Association Meetings, Hawaii, April 3–5, 1969Google Scholar; and Choucri, and North, , “Pressure, Competition, Tension, and Threat: Toward a Theory of International Conflict,” prepared for delivery at the 65th Annual Meeting of the American Political Science Association, New York, September 2–6, 1969.Google Scholar

⁴⁵ Note the distinction between structural equations and model equations. This is especially important when evaluating the last column of Table 1: “A structure is a set of autonomous relationships sufficient to determine the numerical values of the endogenous variables, given the value of the exogenous variables.” But a structure is meaningful only within the context of the model which makes explicit the nature of the equations and the kinds of variable included. See Christ, Carl F., Econometric Models and Methods (New York 1965) 21–22.Google Scholar

⁴⁶ An excellent illustration of this kind of procedure is provided by Duesenberry, James S. and others, eds., The Brookings Quarterly Econometric Model of the United States (Chicago 1965).Google Scholar

⁴⁷ Charles C. Holt, “Validation and Application of Macroeconomic Models Using Computer Simulation,” in Duesenberry and others, ibid., 640.

⁴⁸ In this context sensitivity analysis would be extremely useful: that is, systematically altering the parameters and observing changes in the system and the extent of stability among basic relationships. See the Research Note at the end of the present article for some data on break-points.

⁴⁹ North and Choucri, Nations in Conflict: Prelude to World War I (in preparation).

⁵⁰ Choucri and North, 1968 (fn. 44), and North and Choucri (fn. 49). The specific nature of the empirical formulations providing the basis for the findings discussed in the following is described in the Research Note below and in the last column of Table 1.

⁵¹ Because of the difficulties involved in measuring “demands” this statement is purely inferential.

⁵² Standardized regression (or path) coefficients for Britain are as follows: Population: —.40 (.17); technology; 13.13 (.29); the interactive effect of population and technology: 12.80 (.29); commerce: —.06 (.10); and military capability: —.43 (.11). Parentheses refer to standard errors. See Table 1 and the Research Note at the end of this article for operational definitions. The interactive term adds little to the information contained in the technology variable. There are some instabilities which are currently being ironed out.

⁵³ In the context of a stationary national area during the 1870–1914 period, Britain's domestic population growth averaged .89 per cent annually, increases in iron averaged .89 per cent annually, increases in iron averaged .33 per cent and in steel 2.80 per cent annually, and national income per capita 1.4 per cent. These percentages are based on our data files for this period.

⁵⁴ See Nazli Choucri (with the collaboration of Robert C. North), “In Search of Peace Systems: Scandinavia and the Netherlands,” in Russett, Bruce M., ed., War, Peace, and Numbers [forthcoming, 1972].Google Scholar In 1960 the combined population of the Scandinavian countries was almost ten million lower than Great Britain's population one century earlier. The rates of growth for Sweden and Norway during the 1870–1914 period held annual averages of .65 per cent and .80 per cent respectively. Further comparisons are presented in this paper. Because of probable measurement error in the data series, these and following percentages are approximations at best.

⁵⁵ French domestic population growth averaged approximately .13 per cent annually, while growth in per capita income averaged 2.8 per cent—one of the highest among the powers—and industrial production (steel) almost as high (2.5%). In the French case it was the combination of low population growth and high technological achievement that contributed to lateral expansion. By 1914 the French empire extended to over twenty times its size in 1870.

⁵⁶ For a discussion of empirical data, methodological issues, and statistical results see Choucri and North, “Causes of World War I: A Quantitative Analysis of Longer-Range Dynamics,” in Jurgen Gantzel, Klaus and others, eds., Grossmachtrivalität und Weltkrieg: Sozialwissenschaftliche Studien zum Ausbruch des Ersten Weltkrieges und Historikerkommentare (Gütersloh, forthcoming, 1972).Google Scholar The problems associated with a logarithm transform of the first and third terms of the expansion equation are discussed in Choucri and North, above, as are modifications of the results. We have been able to determine the relative importance of the main effects of population and technology rather than the interaction effects. The implications of interaction, in terms of high collinearity with main effects, are also discussed. These coefficients pertain to analysis with the logarithm transform in the first and third terms.

⁵⁷ Standardized regression (or path) coefficients for Germany are as follows. Population: .77 (.40); technology: .71 (.28); the interactive effect of population and technology: .44 (.20); commerce: .20 (.02); and military preparedness: .08 (.17). In this case there is a distinct interactive effect.

⁵⁸ The average annual rate of population growth of Germany during this period stood at 1.14 per cent approximately; the rate of growth in steel, 5.28 per cent; in iron, 4.36 per cent. The rate of increase in national income averaged 2.3 per cent per year and in per capita income at 1.2 per cent (in comparison with 1.4 per cent for Great Britain, the difference being accounted for in large part by the higher rates of growth in the German population). It should be pointed out that the German rate of growth was not particularly high per se, but in comparison with the other powers (especially Britain and France) and in combination with German technology, it could be considered a potent variable.

⁵⁹ Richardson, Lewis F., Statistics of Deadly Quarrels (Chicago 1960), 52–69.Google Scholar

⁶⁰ High R ² are due, in part, to the loss of degrees of freedom. These, however, are taken into account when computing coefficients and related standard errors.

⁶¹ Singer, J. David, “The Political Science of Human Conflict,” in McNeil, Elton, ed., The Nature of Human Conflict (Englewood Cliffs, N.J. 1965), 144.Google Scholar

⁶² Moll, Kendall M., The Influence of History Upon Seapower, 1865–1914 (Stanford 1968)Google Scholar; North, Robert C. and Lagerstrom, Richard P., “An Anticipated Gap, Mathematical Model of International Dynamics” (Stanford 1969).Google Scholar

⁶³ This finding refers to long-term trends and not to crisis confrontations where alliance commitments may be more influential.

⁶⁴ Thompson, Warren S., Population and Peace in the Pacific (Chicago 1940), 99.Google Scholar

⁶⁵ Ehrlich and Ehrlich (fn. 10), 48.

⁶⁶ Energy Policy: Problems and Objectives, Organization for Economic Co-Operation and Development (Paris 1955), 91.Google Scholar

⁶⁷ Energy Policy: Problems and Objectives, ibid., 94.

⁶⁸ Davis, Otto A. and others, “A Theory of the Budgetary Process,” American Political Science Review, LX (September 1966), 529–47.CrossRefGoogle Scholar Also see Singer, J. David, ed., Quantitative International Politics, Insights and Evidence (New York 1968)Google Scholar, Part 1. Relevant also are McEachron, N. B., “Modelling Macro-Social Tension and Change in American Society,” presented at the Fourth Hawaii International Conference on Social Science, Stanford Research Institute, 1970Google Scholar; and Watt, Kenneth E. F., “State Planning Failures: What to Do About It,” Cry California (Winter 1969–70).Google Scholar

⁶⁹ For an elaboration of the implications of bo:h theoretical framework and empirical data presented in this paper see North, Robert C. and Choucri, Nazli, “Population and the International System: Some Implications for United States Policy and Planning,” prepared for the National Commission on Population Growth and the Future of America, August 1971.Google Scholar

¹ Liu, T. C., “A Simple Forecasting Model for the U.S. Economy,” International Monetary Fund, Staff Papers (August 1955), 434–66.Google Scholar

² H. Wold, in association with Jureen, L., Demand Analysis (New York 1953).Google Scholar

³ In one case single equation estimation methods for recursive systems are called for, in the second simultaneous estimation techniques are appropriate.

⁴ Fisher, Franklin M., “On the Cost of Approximate Specification in Simultaneous Equation Estimation,” in Ando, Albert and others, Essays on the Structure of Social Sciences (Cambridge, Mass. 1963), 32–63.Google Scholar

⁵ Ibid., 92–106.

⁶ Ibid.

⁷ Here we are again indebted to recent econometric literature on problems of modelbuilding. See especially Johnston, J., Econometric Methods (New York 1963)Google Scholar, and Goldberger, Arthur S., Econometric Theory (New York 1964).Google Scholar

⁸ Two variants of this model were developed. In one the independent variables were defined in terms of the rival's attributes and capabilities. And in the second the independent variables were defined as the distance or gap between a state's capabilities and those of the rival. See Choucri and North (fn. 44 of text), 43–61. We are grateful to Raymond Tanter for assisting us in spelling out the implications of these models.

⁹ On empirical grounds alone it is difficult, if not impossible, to determine exactly when a break-point has occurred. It is also as difficult to predict break-points as it is to predict the behavior of the system beyond the break. On the other hand it is possible to test for the existence of a break-point and for the significance of the break. We are grateful to Professor Franklin Fisher of the Economics Department, M.I.T., for a clarification of this problem and for suggesting means of redefining the issues in ways that can be amenable to empirical inquiry.

¹⁰ Theoretically, at least, we postulate that, in the long run, changes are more important than absolute levels, but in terms of short-range day-to-day decision-making levels are probably more important. We have conducted parallel analyses with level variables as well.

¹¹ Estimation was undertaken with the use of the TROLL interactive computer system for the analysis of non-linear models developed by the Econometrics Project at M.I.T. We are grateful to the supervising staff for their assistance.

¹² See Choucri and North (fn. 56 of text) for the rationale underlying the use of logarithm transform in the first and third terms and comparison of results obtained without the transform and without the interactive term.

¹³ Steel per capita can be considered only as a rough indicator of industrial production, and, by extension, of technology. The unavailability of data for other, more appropriate, indicators necessitates the use of this variable for the 1870—1914 period. A critique of our choice of indicators is provided by Firestone, Joseph M., “Remarks on Concept Formation: Theory Building and Theory Testing,” Prepared for Delivery at the 66th Annual Meeting of the American Political Science Association, Los Angeles 1970.Google Scholar

¹⁴ We have employed the Hildreth-Lu iterative procedure for estimating the autocorrelation parameter and specifying the needed adjustments. See Hildreth, Clifford and Lu, John Y., “Demand Relations with Autocorrelated Disturbances,” Technical Bulletin, No. 276 (Michigan 1960).Google Scholar

¹⁵ Operationalizing intersections involved first, isolating those instances in which major powers interactions revolved around disagreements, disputes, conflicts, etc. over colonial territories or potential colonial territories or spheres of influence in Europe and overseas; second, noting the intensity of the intersection on a conflict-cooperation scale designed specifically for purposes of inter-nation and inter-situation comparisons; and third, isolating the most intense intersection variable. (Some index or aggregation would yield a more representative value, but serious methodological problems are involved in the construction of such a measure.) For the interaction scale, see Moses, Lincoln E. and others, “Scaling Data on Inter-Nation Action,” Science, 156, 3778 (July 1967), 1054–59CrossRefGoogle Scholar, and Azar, Edward and others, “Methodological Developments in the Quantification of Events Data,” paper presented at the 1970 Michigan State University Events Data Conference, April 15–16, 1970Google Scholar, for a more intensive discussion of operational issues.

¹⁶ See North and Choucri (fn. 49 of text), for operational definition of violence, and Moses and others (fn. 15), for coding rules.

¹⁷ Moll (fn. 62 of text); North and Lagerstrom (fn. 62 of text).

¹⁸ We have also experimented with gap variables, but have encountered severe identification problems. The same equation was examined employing army budget and total defense budget as alternative measure of the endogenous and exogenous budget variables.

¹⁹ The last term was operationalized as the number of alliance commitments based on the Singer-Small data. See J. David Singer and Melvin Small, “Alliance Aggregation and the Onset of War, 1815–1945,” in Singer, ed. (fn. 68 of text), 247–86.

²⁰ Sub-periods were selected somewhat arbitrarily by trial and error. The possibilities are limited, however, with only 45 years.

²¹ These data are presented for illustrative purposes only. The magnitude ofR ² alone is not an adequate indication of fit. The progressive loss of degrees of freedom effects R ², but not the significance of individual coefficients (since this loss is taken into account when computing the F ratio or t statistic).

²² See Chow, Gregory C., “Tests of Inequality Between Sets of Coefficients in Two Linear Regressions,” Econometrica, XXVIII (July 1960), 591–605.CrossRefGoogle Scholar

²³ For an extended discussion, illustrations, and empirical results see Choucri, Nazli, “Applications of Experimental Econometrics to Forecasting in Political Analysis,” prepared for the Conference on International Relations Forecasting, December 1970; revised August 1971.Google Scholar