Leszek Kolakowski, Death of Utopia Reconsidered

Therefore it's likely that two kinds of mentality--the skeptical and the Utopian--will survive separately, in unavoidable conflict. And we need their shaky coexistence; both of them are important to our culturural survival. The victory of Utopian dreams would lead us to a totalitarian nightmare and the utter downfall of civilization, whereas the unchallenged domination of the skeptical spirit would condemn us to a hopeless stagnation, to an immobility that a slight accident could easily convert into catastrophic chaos. Ultimately we have to live between two irreconcilable claims, each of them having its cultural justification.