The Platonic idea of truth entailed a correspondence with the world of forms

Plato and Euclid developed an indissoluble partnership between geometrical and philosophical ideas of truth. The Platonic concept of the theory of ideas was possible only because Plato had continually in mind the static shapes discovered by Greek mathematics. On the other hand, Greek gemetry did not achieve completion as a real system until it adopted Plato's manner of thinking. (see Ernst Cassirer, The Problem of Knowledge.) The concepts and propositions that Euclid placed at the apex of his system were a prototype and pattern for what Plato called the process of synopsis in idea. What is grasped in such synopsis is not the peculiar, fortuitous, or unstable; it possesses universal necessary and eternal truth. (see transcendence / immanence) This is the space of universal truth that differs from the spaces of a kind of truth that funtions only in the context of local pockets, a truth that is always local, distributed haphazardly in a plurality of spaces, with regional epistemologies. 

The discovery of non-Euclidean geometries radically undermined this concept of truth. (see scientific space

For Kant, judgement and object are strictly correlative concepts, so that in the critical sense, the truth of the object is always to be grasped and substantiated only through the truth of the judgement, once the rules of judgement have been defined. 

"All historical truth involves the simple question of whether or not something actually happened; whether it happened in the way it is told or in some other way." (A.W. Schlegel, quoted in Ernst Cassirer, The Problem of Knowledge, p 228.) For Otto Ranke, historical truth was possible only if the historian put aside every personal parti pris , any advocacy of definitely political, national, or even religious programs. Ranke's great rallying cry zur Sachen selbst, was a call to eliminate self in favor of letting the object alone reveal itself. 

For Nietzsche, truth is "a mobile army of metaphors, metonyms, and anthropomorphisms -- in short a sum of human relations, which have been enhanced, transposed, and embellished poetically and rhetorically and which after long use seem firm, canonical, and obligatory to a people." (in "Truth and Lie in an Extra-Moral Sense." Michel Foucault picked up Nietzche's insight into the "politics of truth." Foucault's position is that intellectuals are inextricably involved in a struggle over "the status of truth and the economic and political role it plays." The option before radical intellectuals is not that of "emancipating truth from every system of power (which would be a chimera, because truth is already power) but of detaching the power of truth from the forms of hegemony, social, economic, and cultural, within which it operates at the present time." (Barry Smart "Politics of Truth" in Hoy, ed. Foucault Reader 165-66) 

For Gilles Deleuze the affective force, level of intensity, desire, or affirmation conveys ideas and ultimately govern their truth-value. The prephilosophical moment of desire not only is unthought, but remains unthought at the very heart of philosophy, because it is that which sustains the very activity of philosophizing. Braidotti alludes to "the unspeakable desire for thought." "The desire to know is, like all desires, related to the problem of representing one's origins, of answering the most childish and consequently fundamental of questions: "where did I come from?" (Braidotti, Nomadic Subjects, p.90) 

For Alain Badiou, the three main strands of contemporary philosophy, the hermeneutic, the analytic, and the postmodern all claim that the ideal of truth as it was put forth by classical philosophy has come to its end. and that for the idea of truth we must substitute the plurality of meanings. (Infinite Thought, p. 46) Instead, Badiou calls for a philosophy founded on singularity, a philosophy of contemporary rationality, a philosophy of the event. Badiou traces the trajectory of a truth as starting with an undecidable event, such as a creation or invention. For Badiou, the axiom of truth opened up by such an event is infinite. His examples include: the appearance, with Aeschylus, of theatrical tragedy; the irruption, with Galileo, of mathematical physics; an amorous encounter which changes a whole life, the French Revolution of 1792. The artistic truth of Greek Tragedy, opened up by Aeschylus is inexhaustible. The work is finite, a pure choice made in what was previously indiscernable. But Tragedy itself, as an artistic truth, continues to infinity. 

In his chapter on Philosophy and art, Badiou revisits the relationships that have been proposed between poetry and philosophy. They include the early fusion of philosophy into the sacred aura of utterance (Parmenides), the separation of poetry from philosophy in Plato, and the inclusion of poetry into the organization of knowledge in Aristotle. Badiou commends Heidegger's re-establishment of the function of poetry to produce truth, while criticizing him for restoring the sacral authority of the authentic poetic utterance. For Badiou, "poetry is the thought of the presence of the presence." (p.99) He recognises that the "undecidable supplement" of the event requires poetic naming. In this sense, the poem produces truths. Yet the truth procedures of philosophy must be subtracted from the eventual singularity that weaves them into the real. For Badiou, philosphical truth is not about sense and the interpretation of its conditions. It must subtract all aura of sense, all trembling and all pathos, to seize truth's proving of itself as such. (p.104) 

Antonio Negri gives a more overtly militant dimension to truth when he claims that "The sole criterion of truth, for me, is action. Truth is itself an action .... a confrontation. When one acts, one goes beyond solitude because to act is to search for the truth, and truth always appears in common." (Negri on Negri, p.26)