That foreign policy is a social product, that it is in particular the outcome of a political process and an element in the national political system—these are general notions that few scholars would in principle dispute. But in practice foreign policy has been commonly portrayed in exactly the opposite way. It is viewed as some-thing with its own life, essentially cut off from domestic politics, existing primarily in the international sphere. Scholars do of course recognize that domestic factors play a role, but the implied connection is often extremely amorphous and general, with no attempt on the whole made to specify the mode of linkage in a concrete and testable way. Thus America's return to isolation after the First World War is commonly attributed to the unwillingness of her people to bear the burden of world power; British and French foreign policy after 1924 is explained in terms of the deep-seated pacifism of the masses. The actual mechanism of linkage is not spelled out. On those occasions when a specific relation is described the very language used often betrays an unwillingness to see it as a legitimate, integral part of a normal political process. Such things as public opinion and party and interest-group politics are seen basically as exogenous forces, “intruding” or having an “impact” on the policy-making system, not as regular parts of it.