Thomas F. Homer-Dixon, Environment, Scarcity, and Violence (Princeton: Princeton University Press, 1999).

You may thrust nature out with a pitchfork, so the tag from Horace goes, but she will quickly return. No doubt this was meant to apply to garden weeds but it equally accords with the study of international relations. There is a subtext to the social sciences, in which every so often an attempt is made to show that human affairs are in the grip of powerful natural agencies, or at least that they are strongly influenced by them. Thomas Homer-Dixon's Environment, Scarcity, and Violence follows in this vein. Homer-Dixon sets out to re-establish what he calls "nature-social" explanations of possible threats to national and international security. Although his thesis proves more nuanced than bald environmental determinism, the purpose of the volume is to trace various paths by which the natural world may give rise to intra- or inter-state conflict.

There is an obvious argument for "bringing nature back in" to the interpretation of world politics. Just as the diversity of soils and climates means that production costs under any given technology are unlikely to be the same everywhere, so too will the costs of trading with others or fending off aggressors vary from place to place. Nevertheless, efforts to establish the role of nature in social phenomena have been episodic. Every so often, meteorologists try to account for historical events on the basis of climatic changes. The most resounding environmental explanation was probably Karl Wittfogel's "Oriental Despotism" thesis, which attributed underdevelopment in Asia to the flourishing of repressive empires that supposedly arose wherever farming depended on centralized irrigation and flood control in great river valleys. Wittfogel fell afoul of the Stalinists, who would accept no deviation from the Marxist orthodoxy that proper (i.e., communistic) social organization could overcome all natural obstacles. One might think capitalism also challenges Wittfogel's thesis, since modern economic growth in Asia patently shows that the continent has not in fact been the prisoner of natural constraints. Most modern commentators seem to take this line. They feel obliged to acknowledge that the environment is "a good thing" that should be preserved at almost any cost, while ignoring the effect the natural world may actually have on human affairs.

The uneven distribution of global poverty is nevertheless so intriguing that it still attracts the attention of the occasional non-geographer. Fundamentally, the issue is what it always has been: whether natural constraints hold back disfavored societies or whether the constraints are social, political or economic. Homer-Dixon belongs to the first school, believing that the world will tend increasingly to bifurcate into great patches of resource "haves" and "have-nots." Whether or not we believe this distressing prediction, it is only fair to consider the potential for environmental problems in lands very different from the developed countries.

Sixty to 70 percent of the world's population still lives in rural areas, and more than 40 percent depends on so-called "biomass fuels" like straw and cow dung, while 1.2 billion people lack access to potable water. A graphic illustration of the challenge to the imaginations of those of us who dwell in the rich, urban and wired world comes from the 1999 BBC television series on the "1900 house" experiment, in which a modern family finds itself utterly shaken when obliged to make do with the Western domestic equipment of a century ago -- limited technology, admittedly, but not one that compares with cooking over dried cow dung.

According to Homer-Dixon, two processes describe how environmental scarcity leads to conflict. One is ecological marginalization, when groups are driven (often by their own population growth) onto infertile soils, unstable hillsides, the fringes of deserts or into the depths of forests. The other is resource capture, when elites seize the lion's share of some diminishing resource. Understanding one or both processes is necessary to interpret the strife in Chiapas, Haiti, South Africa, Pakistan, Peru, the Philippines and elsewhere. The deeper questions, however, concern the extent to which these issues are genuinely environmental ones, and the circumstances under which they constitute threats to national or international order.

Homer-Dixon does not believe there will be wars between states over resources. Most of the under-endowed countries, he writes, are too poor for war, or at least for war with other states. This, though, is a sanguine position in view of the generally pessimistic tone of his book. The states intervening in the Congo, for example, would appear at first glance to be too poor for military adventures -- which cannot all be paid for by misdirected IMF funds -- yet that has not deterred them from dispatching armies across borders. Potential gains as well as costs have to be considered, and the enormous wealth of the mineral-rich Congo may tempt neighboring countries to engage in aggression that, strictly speaking, they cannot afford. Some have expressed the opinion that such conflicts may be merely peripheral to the security interests of the developed countries. But I doubt this, given that we are speaking here about a set of countries that includes Pakistan, India, Indonesia and China.

Homer-Dixon correctly notes that even sub-national violence can drive states to become authoritarian and thus pose potential dangers to their neighbors. He is also inclined, after the fashion of thematic writers, to suggest that scarcity-induced migrations may carry conflict into hitherto unaffected regions. But in general he does not anticipate inter-state resource wars, not even over water supplies, and he mostly portrays environmental issues within states as merely contributing to underdevelopment rather than determining it.

Then there is the question: What exactly is the scarce resource in question? Is it cropland, fuel, wood or water? Or is it something quite distinct from physical resources -- such as creativity, which develops the technologies that adapt available resources to modern rates of population growth? For most economists the answer lies in the response more than in the challenge. The weakness of a geographical approach is that it takes one factor of production -- land -- far too seriously. It makes no particular sense to think of land as a fixed resource; for instance, we can plant it with superior-yielding, genetically modified crops, which amounts to much the same thing as increasing its surface area. Indeed, the heart of the matter is less the dilemma of static resource endowment than its more general solution: the social, political and economic arrangements necessary to generate new technology and stable property rights capable of remedying resource scarcity.

Homer-Dixon would expect an economist to take such a cavalier view of human suffering. Thus, he devotes whole chapters to the debate between the optimistic view espoused by a majority of economists, who see the underlying issue as a failure in the supply of ingenuity, and the neo-Malthusians, who see the issue either as one of overpopulation or the maldistribution of wealth and power. In these sections he goes so far as to accuse economists, tout court, of believing that the price elasticity of ingenuity is nearly infinite. But of course if that were true the world would be drowning in fresh gadgets and wheezes.

Some economists have undoubtedly been too glib about the fluidity of the human response to environmental scarcity. Joseph Stiglitz of the World Bank has written as though institutions adjust automatically to changing economic incentives, while the late Julian Simon gave hostages to fortune by insisting that growing populations generate a proportionate supply of new ideas, as if every country's institutions are equally adept at stimulating creativity and bringing the results to fruition. In reality the situation in poor countries is even worse than it appears, since the precious few skilled workers often emigrate to richer pastures. India and South Africa, among others, have suffered particularly egregious brain drains.

The author argues well past the concept of simple resource scarcities to the question of coalitions that block ingenuity. Given a rising price for a resource (growing scarcity), elites do not necessarily feel inspired to invest in improving productivity; rather, they resort to securing as much of that resource as possible for themselves. To cite an example, genocide in Rwanda was, in Homer-Dixon's telling, the outcome of a "conventional struggle" among elites for control of the Rwandan state; land scarcity played only a minor role. But here, as elsewhere, the author's dose of odium theologicum with respect to economics lets him down. He claims that land scarcity "restricted the alternatives for elite enrichment outside of government." It would have been more in line with his concept of resource capture had the elites extended their control over the scarce natural resource: namely, land. Although he does not explain which response a given group will choose, it remains true that rising real prices for resources may play out in the political arena by tempting elites into uncreative responses. This only goes to show that, for practical purposes and policy ends, so-called environmental problems do lie in the response more than in an intrinsically constricted "geography." The economist William Baumol has developed an "Allocation of Talent" model to show how each society "chooses" whether to induce talented individuals to take up productive, unproductive or destructive activities. This expresses more exactly Homer-Dixon's observations on the choices facing the elites of poor countries. Needless to say, too often they respond to perverse incentives.

Homer-Dixon's thesis is repeatedly qualified and surrounded by many methodological doubts. If we cut to the bare bones, we do find an acknowledgement that the issue is not merely whether one is a geographer but whether one is an optimist or a pessimist. Will humanity be capable of expanding scarce resources? The solution partly depends on how long one is prepared to allow the processes to work themselves out. Instant solutions are certainly not in the cards. The remaining part of the answer is philosophical and depends on one's world-view. In that respect Homer-Dixon is a deep pessimist who does not think that enough ingenuity will, or indeed can, be forthcoming.
This is a faintly absurd position when we think of how many nations have grown rich despite the fact that each was once poor. Have we really crossed a threshold beyond which humanity can no longer help itself? One of the author's explanations for his pessimism is that the scientific response will be inadequate because there are limits to human cognition. But most of the technologies needed to raise resource productivity or reduce waste already exist; they are simple and cheap. The obstacles to their further spread are political, i.e., the perverse incentives to which Homer-Dixon usefully draws attention.

Whether there is an intellectual barrier preventing science from solving every problem is beside the point. There is no reason for giving up on the poorest countries in the name of an ultimate epistemological limit, for the world has come nowhere near universally diffusing the tool kit it already possesses. But this book does not make too strident a case for the global importance of environmental scarcities, and the author is to be congratulated for mostly, though not always, steering clear of exaggeration. In terms of its anti-market tone and depressing policy implications, however, Environment, Scarcity, and Violence is not an appealing volume.