Modern Western Philosophy: From Descartes to Nietzsche and the Analytic–Continental Split

Modern Western philosophy conventionally begins with René Descartes, who sought an indubitable foundation for knowledge through methodical doubt, arriving at the cogito ('I think, therefore I am') as the one certainty immune to even the most radical skeptical scenario. Descartes's mind-body dualism and his rationalist confidence that reason alone, independent of sensory experience, could establish metaphysical truths set the terms for a century of rationalist system-building by Spinoza and Leibniz, who each constructed comprehensive metaphysical architectures aiming at logical necessity comparable to geometry.

British empiricists John Locke, George Berkeley, and David Hume challenged rationalist confidence by insisting all knowledge originates in sensory experience. Locke argued the mind begins as a tabula rasa; Berkeley radicalised empiricism into idealism, denying the existence of matter independent of perception; and Hume pushed empiricist skepticism to its most unsettling conclusion, arguing that causation is not a rationally demonstrable necessary connection but merely a habitual expectation formed by repeated experience, and that induction itself cannot be rationally justified — a problem that still troubles philosophy of science today.

Immanuel Kant, awakened by his own account from 'dogmatic slumber' by Hume's skepticism, attempted a critical synthesis in the Critique of Pure Reason, arguing that the mind actively structures experience through a priori categories of understanding (such as causality) and forms of intuition (space and time), so that we can have certain synthetic a priori knowledge of the phenomenal world while remaining permanently unable to know things-in-themselves (noumena). His ethical theory, grounded in the categorical imperative — act only according to a maxim you could will to become a universal law, and treat humanity always as an end and never merely as a means — established a deontological alternative to consequentialist ethics that remains foundational to modern moral and political philosophy, including contemporary human rights discourse.

Friedrich Nietzsche's late-nineteenth-century critique of morality challenged the entire post-Kantian edifice by arguing, in On the Genealogy of Morality, that conventional moral values are not timeless rational truths but historically contingent products of power relations, with Judeo-Christian 'slave morality' representing a resentment-driven inversion of an earlier aristocratic 'master morality.' His proclamation that 'God is dead' signalled the collapse of transcendent metaphysical guarantees for meaning and value, demanding instead the self-overcoming of the 'last man' toward the Übermensch who creates values rather than passively inheriting them — a challenge that deeply shaped twentieth-century existentialism, postmodernism, and critical theory worldwide.

The twentieth century saw Western academic philosophy split along a now-famous methodological divide: the analytic tradition, developed by Frege, Russell, Moore, and later Wittgenstein and Quine, emphasised logical rigor, precise language analysis, and close engagement with formal logic and the philosophy of science, becoming dominant in Anglo-American universities; the continental tradition, encompassing phenomenology (Husserl, Heidegger), existentialism (Sartre, de Beauvoir), and critical theory (Adorno, Horkheimer, and later Foucault and Derrida), remained closer to historical, literary, and socio-political concerns and dominant in continental Europe and much of Latin America and postcolonial academia. Contemporary global ethics increasingly works to transcend this divide, drawing simultaneously on analytic moral philosophy's precision (as in Peter Singer's utilitarian arguments for effective altruism) and continental and postcolonial critiques of universalist ethical frameworks that ignore historical power and cultural difference, producing genuinely cross-traditional approaches to questions like global poverty, climate justice, and human rights.