Georg Lukács’ The Destruction of Reason and Max Horkheimer’s The End of Reason both center on the theme of reason, as their titles indicated. However, there is a profound divergence in their intellectual foundations and teleological outlooks. This study examines these divergences through two core lenses: the philosophers’ contrasting attitudes toward Stalinism and their differing conceptions of reason’s prospects. As a consequence, their views on praxis, individuality, and the role of collective vs. individual struggle diverge: Lukacs prioritizes material transformation and collective action, while Horkheimer emphasizes critical reflection and the preservation of individual autonomy. Despite both being considered as foundational figures of Western Marxism, their disagreements reflect deeper tensions within Marxist thought regarding emancipation, rationality, and the relationship between theory and political practice. This paper argues that these differences stem not from contradictory commitments to Marxism, but from distinct responses to 20th-century political realities (e.g., fascism, Stalinist governance) and divergent interpretations of Marxism’s core tenets, particularly regarding the nature of reason and the path to human emancipation.