This book began by raising two interrelated questions. The first – why have the major immigrant-receiving states of Western Europe historically permitted and often abetted relatively high levels of immigration? – is genuinely perplexing given the general public's opposition to new immigration and, as we saw in Chapter 3, the emergence and the sometimes spectacular growth of anti-immigrant groups and political parties since the early 1970s. The second question – to what degree can governments and states effectively regulate immigration flows and manage the domestic social and political fallout they precipitate? – was inspired by the work of scholars who insist that the capacity of Western European states to implement rational and self-serving immigration and immigrant policies is now (in contrast to the not so distant past) severely constrained by exogenous and endogenous forces and actors. Implicit in both questions are a deep-seated pessimism about the current and projected future condition of interdependence sovereignty and concern about whether and to what degree contemporary mass immigration flows are a cause and/or a symptom of eroding sovereignty.

Against the backdrop of this pessimism and concern, three scenarios in which interdependence sovereignty could potentially be eroding were raised in the Introduction.