Mannheim distinguishes four types of utopia: chiliasm; the liberal-humanist idea; the conservative idea; and the socialist-communist utopia. Each of these is characterised by a different orientation to, and experience of, time; and it is the treatment of historical time which Mannheim sees as the organising principle of the utopian mentality. Levitas, The Concept of Utopia, p.82

This [Chiliasm’s] essence is an experiential one, for in chiliastic or millennial groups Mannheim argues that action is not inspired by ideas, but by something much more deeply rooted in the ‘vital and elemental levels of the psyche’. Whereas millennialism appears to be orientated to the future, Mannheim argues that the chiliast ‘is not actually concerned with the millennium that is to come’, but with a leap over into ecstasy. "The only true, perhaps the only direct, identifying characteristic of Chiliastic experience is absolute presentness … . For the real Chiliast, the present becomes the breach through which what was previously inward bursts out suddenly, takes hold of the outer world and transforms it.” [Mannheim, Ideology and Utopia, Routledge & Kegan Paul 1979, p.173] Chiliasm is therefore implicitly hostile to all actually existing conditions and processes of becoming, as it seeks this breaking through into a qualitatively different kind of existence, and what it seeks ‘can only be adequately satisfied in Kairos’. Kairos is a theological term, whose meaning is explained by Paul Tillich as ‘fulfilled time, the moment of time which is invaded by eternity’, and distinguished from ‘perfection or completion in time’. Levitas, The Concept of Utopia, p.82

The idea of breaking through into an experience of fulfilment, of wholeness, appears in different ways in both Sorel and Bloch. For Sorel the importance of proletarian violence is precisely that it generates an experience of freedom and full possession of the self, and it is the heroic state of mind produced that is important, rather than the actions that flow from it. Sorel’s debt to Bergson is explicit. Mannheim and Bloch are both critical of Sorel (and of Bergson) and particularly of the ease with which Sorel’s approach was incorporated into fascism. Yet both identify experience as an important element in utopia. Levitas, The Concept of Utopia, p.82-83

Mannheim’s second type of utopia is the liberal-humanitarian idea. Unlike chiliasm it is an essential feature of this type that ideas do guide activity, and there is an emphasis on reason and on free will. The gap between the existing state of things and the ideal world constructed by bourgeois liberalism was bridged by ‘the belief that reality moves continually towards an even closer approximation to the rational’ – a belief of which Mannheim is acutely critical in this context, although it later emerges as an essential element in his own argument. Whereas in chiliasm utopia must break in abruptly from outside, in this mode utopia becomes a goal set in the future, towards which existing processes are moving […]. The world-view embodied here represents not the oppressed strata, but ‘the middle stratum that was disciplining itself through conscious self-cultivation and which regarded ethics and intellectual culture as its principal self-justification (against the nobility) and unwittingly shifted the bases of experience from an ecstatic to an educational plane’. Its characteristic time-orientation involves progress rather than kairos. Levitas, The Concept of Utopia, p.84

The liberal-humanist utopia is followed by that of conservatism. In many ways it seems inappropriate, on Mannheim’s own definitions, to describe this as a utopia rather than as an ideology. For the conservative utopia emerges in response to the liberal utopia, in opposition to it in order to protect the social position of the dominant class, and is dedicated to re-enacting the past and preserving tradition. It celebrates the past as immanent in the present, and time is perceived as duration. Mannheim’s characterisation of conservatism applies with uncanny accuracy to neo-conservatism as it developed during the 1980s, some fifty years after he was writing; it is correct even in that neo-conservatism (at least in British politics) emerged as a reaction to the growth of economic liberalism within the Conservative Party. But if Mannheim’s description of the nature and function of conservatism is correct, why does he call it a utopia? Mannheim is aware of the paradox here. He argues that the ‘conservative mentality as such has no utopia’. However: "the counter-attack of opposing classes and their tendency to break through the limits of the existing order causes the conservative mentality to question the basis of its own dominance, and necessarily brings about among the conservatives historical-philosophical reflections concerning themselves. Thus, there arises a counter-utopia which serves as a means of self-orientation and defense.” [Mannheim, Ideology and Utopia, Routledge & Kegan Paul 1979, p.206,207] Levitas, The Concept of Utopia, p.85

But because he is examining the shifting constellation of the utopias of different social groups in their conflicts with one another, it becomes necessary to describe this mode of ‘incongruous’ thought as a utopia as well, in spite of the fact that his description makes it more properly an ideology than a utopia. What this illustrates above all is the problematic nature of the distinction between ideology and utopia in the first place, for when conservatism is provoked by its opponents into the need for political legitimation it may also find it necessary to do this by the affirmation of a particular form of society, even if it is a form deemed to be represented by the survivals of the past in the present, whose preservation for the future becomes the overriding concern. Levitas, The Concept of Utopia, p.85

Mannheim’s fourth form of utopian mentality is the socialist-communist utopia. Like conservatism this derives its preoccupations from the need to counter the other forms of utopia. Time here is seen as a series of strategic points in history, rather than a gradual progress as in the liberal-humanist idea; socialism shares with the liberal idea the location of a perfect world in the future, but here it occupies a much more specific point in time, the collapse of capitalism. It shares also the liberal opposition to the status quo, to the conservative affirmation of existing reality and to the chiliastic mentality, especially as it is expressed in anarchism. Levitas, The Concept of Utopia, p.85-86