Colonialism 563 one value that the dependent variable can take.Its uniqueness is twofold.First, it involves the explicit or implicit use of force by the colonial power over the annexed region.Second,the relationship is exclusive;that is,the colonial power acts unilaterally and not in concert with other powers (and often explicitly to exclude them). To express the thing to be explained more generally,colonialism is simply one example of interstate interaction occurring along two dimensions.[For ease of exposition,I refer to potential colonial powers as "home countries" (that is,sources of foreign investment)and to potential colonized regions as "host countries"(that is,sites of foreign investment).The first dimension of variation is the extent to which a home country engages in the use or threat of military force in its relations with the host country.Variation along this dimension runs from military intervention at one limit to the absence of government involvement at the other.The second dimension is the degree to which home countries act in concert toward a host country.Variation along this dimension runs from unilateral and exclusionary action by a home country at one limit to cooperative multilateral action by many home countries at the other.Those so inclined might imagine a two-by-two matrix with the use of force (or conflict more generally)between home and host countries on one axis and conflict among home countries on the other.The four positions described here would occupy the four cells (home-host and home-home conflict is colonialism,home-host and home-home cooperation is peaceful multilateral negotiation,and so on),but there is no reason to believe that variation does not allow for a continuum of outcomes.In this context,colonialism (the unilateral use of force)is one possible outcome.Other potential outcomes include multilateral use of force,bilateral arms-length negotiations,or multilateral negotiations-and gradations in between. Other characteristics of home-country policy may well be of interest.For example,it may be important to understand the domestic distributional implications of a government's policy toward the foreign assets of its citizens, such as the subsidization of overseas investors by national taxpayers.It may also be important to understand the ways in which relations between home and host countries,or among home countries,are institutionalized at the international level.7 Other potential topics suggest themselves,but I focus on those mentioned above. In any case,the issues addressed here involve home-country conflict with host countries and conflict among home countries.These capture much of the theoretical debate and historical experience.Putting the two dimensions together covers everything from unilateral military intervention leading to colonial annexation,through multilateral intervention that preserves the 7.For a discussion of the analytical issues in the development of such international institutions, see Robert Keohane,"International Institutions:Two Approaches,"Intemational Suudies Quarterly 32 (December 1988),pp.379-96.See also Michele Fratianni and Johr Pattison,"The Econamics of International Organization,"Kyklos 35 (1982),pp.244-62