Mainstream politicians tend only to make the economic case for immigration and rising diversity, rather than underscore the cultural contribution that immigrant and minority groups make to our national life. This is why arguments over net immigration or the allocation of jobs are unlikely to resonate over the longer term. Aside from exploring more innovative ways of addressing cultural anxieties, there are also too few voices in modern politics countering the claim by extremists that Muslims pose a specific threat to values and national cultures.

The diverse attempts at revisionism were the most obvious symptom of a major crisis of direction: even at its best (Bad Godesberg and Crosland), revisionism proceeded mainly in the negative - that is, by seeking to abandon ideological baggage which appeared to have become dysfunctional. While the defenders of orthodoxy remained committed to the vision of the final goal, no grand new ideas appeared on the horizon of European socialism. It was thus ill-equipped to meet the challenge of power which opened up in the 1960s in Britain, Germany and Italy; unprepared to face the strategic implications of the revival of working-class militancy; surprised at the reawakening of Marxism among the intelligensia; disconcerted by the new radicalism expressed by feminism; and unaware of how the growth of interdependence was leading to the decline of the nation-state.

Revisionists could never understand the difference between watering down traditional socialism and establishing a new framework. Unable to achieve the latter, they remained content with the former. Over successive decades, the parties of the West European Left, socialists as well as communists, made no major conceptual advances.

Revisionism, to be successful, required considerable preparation, rather than shock therapy, and some understanding of party structure and party management. In most continental socialist parties - but not in the British Labour Party - this was the precondition for obtaining leadership. In Britain, the road to the top party job was through the parliamentary group and the cabinet or shadow cabinet, not the party machine, which counted for little.

The paradox of the new revisionists was that while they were relinquishing the belief on the ‘continuous upward line of social progress’, they were adopting a belief in the ‘continuous upward line’ of economic growth under capitalism.

Logic and politics have little in common. Successful political ideologies and parties are seldom consistent.

Belief in progress was compatible with the renunciation of a militant doctrinal committment to anti-capitalism, for it is a position shared by all ‘pro-industrial’ ideologies. Liberalism is even more committed than Marxism to an optimistic view of the emancipatory potential of technical progress and science. By rejecting the most overtly anti-capitalist component of their ideological framework, the socialists had opened a route towards a more consequential alliance with liberalism. The revisionism of the late 1950s wished to tone down the differences with liberalism, while distancing itself not only from communism - repeatedly denounced since its inception - but also from traditional socialist anti-capitalism.