Seyyed Hossein Nasr (born 7 April 1933, Tehran, Iran) is an Iranian-American philosopher, theologian, and scholar of Islamic studies and comparative religion. He is University Professor (the university's highest faculty rank) of Islamic Studies at George Washington University, a position he has held since 1984. Nasr is widely regarded as one of the most prominent living exponents of the Traditionalist or Perennialist school of thought - a philosophical current holding that a universal, transcendent truth underlies all major religious traditions. His work spans Islamic philosophy, Sufi metaphysics, the philosophy of science, and the relationship between religion and the natural world.

Nasr was educated in Iran and then in the United States, receiving undergraduate training in physics and mathematics at MIT and completing his doctorate in the history of science and learning at Harvard University in 1958. He returned to Iran and taught at the University of Tehran, where he founded the Iranian Academy of Philosophy. Following the 1979 Islamic Revolution, he emigrated to the United States permanently. His scholarly output is extensive, with authored books numbering in the dozens and articles in the hundreds. He has lectured widely across North America, Europe, and the Islamic world, and has engaged in formal interfaith and inter-philosophical dialogues with thinkers from Catholic, Jewish, Buddhist, and Hindu traditions.

Nasr is the most prominent Muslim voice within the Traditionalist school, a movement associated with thinkers such as René Guénon, Frithjof Schuon, and Ananda Coomaraswamy. Traditionalists hold that authentic religion participates in a single primordial wisdom - the philosophia perennis - and that the modern world represents a descent from this sacred order. Nasr applies this framework specifically to Islam, arguing that Islamic philosophy, science, and art are intelligible only within a metaphysical context rooted in the Quran and the Sufi intellectual tradition, particularly figures such as Ibn Arabi and Mulla Sadra. He is a practitioner and scholar of Sufism, specifically within the Shadhili order.

A recurring theme in Nasr's work is the critique of modern Western science as a worldview rather than a methodology. He argues that the quantitative, materialist orientation of modern science - beginning with the Scientific Revolution of the sixteenth and seventeenth centuries - entails a desacralization of nature with destructive consequences for both human civilization and the natural world. He contends that Islamic intellectual history preserves cosmological and epistemological frameworks that situate natural knowledge within a sacred order, and that recovery of such frameworks is necessary for any adequate response to environmental and spiritual crisis. This position places him in direct disagreement with those who regard the methods and conclusions of modern science as culturally neutral or universally applicable. Science and Sacred Cosmology.

Nasr's standing within Islamic studies and philosophy of religion is substantial; he has received honorary doctorates from numerous institutions and was named among the 500 most influential Muslims in the world by the Royal Islamic Strategic Studies Centre (listed from the inaugural edition). Critics from within secular academia argue that his Traditionalist framework is metaphysically presupposed rather than argued, making it resistant to empirical or analytical challenge. Some Muslim scholars contend that his Sufi-inflected interpretation marginalizes the diversity of Islamic theological and legal traditions. Secular historians of science dispute his characterization of modern science as inherently desacralizing, arguing that the relationship between science and religion is more historically complex than his framework allows. See Debate: Nasr's Perennialism.

• Traditionalist Perennialism: Nasr's own position, holding that all authentic religious traditions share a common transcendent source and that modernity represents a rupture from primordial wisdom.
• Science and Sacred Cosmology: Nasr's argument that modern science's quantitative methodology is not epistemologically neutral and that Islamic intellectual tradition offers an alternative cosmological framework.
• Secular Academic Critique: The view that Nasr's Traditionalism is a theological program dressed in scholarly language, and that its claims about science and modernity are not independently defensible.
• Orthodox Sunni Critique: The position, held by some Muslim scholars, that Nasr's Sufism and Perennialism depart from or subordinate the authority of Islamic jurisprudence and theology.

• Seyyed Hossein Nasr - History
• Seyyed Hossein Nasr - Debate
• Traditionalism and Perennialism
• Islamic Philosophy
• Sufism
• Heliocentrism and Islamic Astronomy
• Philosophy of Science
• Religion and Science - Debate

1. Nasr, Seyyed Hossein. Knowledge and the Sacred. Edinburgh University Press, 1981. (Gifford Lectures, 1981)
2. Nasr, Seyyed Hossein. The Need for a Sacred Science. State University of New York Press, 1993.
3. Nasr, Seyyed Hossein. Islam and the Plight of Modern Man. ABC International Group, 2001.
4. Nasr, Seyyed Hossein. The Garden of Truth: The Vision and Promise of Sufism, Islam's Mystical Tradition. HarperOne, 2007.
5. Hahn, Lewis Edwin, Randall E. Auxier, and Lucian W. Stone, Jr., eds. The Philosophy of Seyyed Hossein Nasr. Library of Living Philosophers, vol. 28. Open Court, 2001.
6. The Royal Islamic Strategic Studies Centre. The Muslim 500: The World's 500 Most Influential Muslims. Amman, 2009- (Nasr listed from inaugural edition).
7. Borella, Jean. “René Guénon and the Traditionalist School.” In Modern Esoteric Spirituality, ed. Antoine Faivre and Jacob Needleman. Crossroad, 1992.