At the height of its modern revival, Stoicism is due a sustained philosophical provocation. While recognizing the tradition's practical wisdom, moral rigor, and therapeutic relevance, this book argues that Stoicism's promise of rational mastery, emotional invulnerability, and inner tranquility obscures the deeper existential dimensions of human life. Through a series of thematic encounters-structured around suffering, interhuman relations, happiness, and free will-the manuscript brings Stoic thought into dialogue with Dostoevsky, Heidegger, Buber, Frankl, Taylor, Kant, Nietzsche, and contemporary critics of modern "safetyism." Each chapter begins with a reconstruction of Stoic "basics," illuminating the coherence and appeal of Stoicism's ethical architecture, before exposing its limits when confronted with existential complexity, relational vulnerability, and the groundlessness of human freedom. Drawing from existential phenomenology, dialogical philosophy, and psychological accounts of fragility and resilience, the book contends that Stoicism flattens the meaning of suffering, misconstrues the depth of human relationality, and overestimates the stabilizing power of reason. Where Stoicism seeks equanimity, the existential tradition reveals the irreducible role of angst, contingency, and the self's struggle for authenticity. Where Stoicism upholds self-sufficiency, thinkers like Buber and Heidegger expose the primordial structures of being-with-others. And where Stoicism reconciles freedom with Fate, Kant, and Nietzsche challenge the adequacy of rational assent as a model of agency. Ultimately, Against Stoicism argues that living well requires not the neutralization of suffering but its interpretation; not detachment from others but authentic encounter; not assent to a system but a sustained reckoning with the ambiguity of human existence.