Ask someone from Europe or North America to name a philosopher and they might say Socrates, Plato, or Aristotle; perhaps Descartes, Leibniz, Kant, Marx, or Nietzsche. Ask them to name an Islamic philosopher, and you may be met with silence. At a stretch, they might have heard of Avicenna (a Latinisation of Ibn Sīnā), the most famous scholar of the Islamic Golden Age (from the eighth to the 13th century AD). Yet there is one thinker in particular whose relative obscurity in the West belies his significance not just to Islamic philosophy but to global intellectual history.

Despite being widely considered the greatest philosopher in modern Islamic thought, the Persian ‘theosopher’ Mullā Ṣadrā (1571-1635), who flourished under the Safavid dynasty, is little known to non-specialist Western readers. Ṣadrā was a philosophical polymath, expert in a stunning range of intellectual fields, including Aristotelian metaphysics, Greek Peripatetic philosophy and Neoplatonic ontology; Persian Illuminationism (ḥikmat al-ishrāq), Sufi mysticism, the Twelver Shīʿī tradition and Qurʾānic hermeneutics. His most important work, al-Ḥikmah al-mutaʿāliyah fī al-asfār al-ʿaqliyyah al-arbaʿah (The Transcendent Philosophy of the Four Journeys of the Intellect, known as Asfār), synthesised a dazzling array of disciplines and methods into an epistemological summa, as influential on Islamic philosophy as Thomas Aquinas’s Summa Theologica (1225–74) or Kant’s Critique of Pure Reason (1781, rev. 1787) were on Western thought.

Yet Ṣadrā also pioneered his own method of philosophy that blended discursive reasoning and the rational contemplation of abstract concepts with what is known in the Islamic tradition as spiritual ‘wayfaring’ (sulūk), a term describing the philosopher’s personal, intuitive, esoteric, mystical and spiritual journey towards truth. Al-ḥikmah al-mutaʿāliyyah (usually translated as ‘transcendent philosophy’, ‘transcendent wisdom’ or ‘transcendent theosophy’) was the name Ṣadrā gave to his system. His major contribution to metaphysics and ontology was to argue for the primacy of existence (aṣālat al-wujūd) rather than the primacy of essence or quiddity (aṣālat al–māhiyyah), which had been the philosophical orthodoxy for centuries. As Ṣadrā put it in Shawāhid al-rubūbiyya (The Divine Witnesses), a summary of the major questions explored in Asfār: ‘Existence deserves more than anything to have a reality because it is through existence that what is other than being has a reality […] existence is that by which everything that is real gets its reality.’

From that insight, Ṣadrā developed his theory of the gradation or modulation of existence (tashkīk al-wujūd), based on a hierarchy and emanation of existence, beginning with the perfection of the Necessary Being (wājib al-wujūb) and flowing through everything that exists. Ṣadrā thus attempted to resolve the ancient philosophical problem of the relationship between unity and multiplicity by arguing that the whole of existence is One – in harmony with the central Islamic concept of tawḥīd or ‘oneness’ (of God) – yet differentiated according to various degrees, modulations, grades and intensities of existential perfection and imperfection.

In order to grasp Ṣadrā’s place in intellectual history, it is crucial to understand that the Western notion of philosophy as a secular practice aimed at knowledge divorced from revelation is virtually nonexistent in Islamic philosophy. ‘Analytic’ philosophy, for instance, would be considered by Persian thinkers as ‘weaving’ (bāftan); a form of ‘mental gymnastics’ rather than the discovery of truths (yāftan al-ḥaqq) about experience, knowledge, and reality. As Seyyed Hossein Nasr argues in his Islamic Philosophy from its Origins to the Present (2006), the ‘rapport between philosophy and prophecy’ has deep historical roots. Nasr credits prophecy – meaning the attempt to understand ‘higher or deeper orders of reality’ rather than mere clairvoyance – with the ‘genesis of Greek philosophy’ in Parmenides and Pythagoras. By this logic, the centrality of prophecy is not peculiarly Islamic, but is at the heart of the world’s great spiritual traditions, from Hinduism and ancient Egyptian mythology to Buddhism, as well as the Abrahamic religions of the book that have shaped the intellectual culture of the West.

We also need to view Ṣadrā’s work in the context of the historical and cultural cross-currents between Western and Eastern thought that determined the development of Islamic philosophy. Ṣadrā’s Asfār marks the apotheosis of the tradition of the grand synthesis, an approach that gathered pace after Shihāb al-Dīn Suhrawardī (1154-91) founded the School of Illumination, combining rational philosophy, gnosis (‘irfān), mysticism, revelation, and exegesis (tafsīr) into a comprehensive metaphysical and ontological system.

Ṣadrā’s synthetic achievement should be placed in the context of an earlier controversy: the traditional (and often bitter) division between practitioners of kalām and those of falsafa (a loanword from the Greek ‘philosophy’). Kalām, usually translated as ‘theology’, is a school of thought closely focused on doctrinal and legal debates and defending the tenets of Islam with reference to the Qurʾān and the teachings of the Prophet Muhammad. Meanwhile, ḥikmat (‘wisdom’) or falsafa, as its name suggests, sought to reconcile and integrate the teachings of Plato, Aristotle and their Muslim interlocutors with the Islamic revelation. The division between these two approaches structured much post-classical Islamic philosophy.

Early Islamic philosophers such as al-Kindī (c.801-873) and al-Fārābī (c.870-951) had been content to adapt and develop the insights of the Greek tradition alongside the teachings of the Qurʾān. But Muhammad ibn Idrīs al-Shāfiʿī’s (767-820) al-Risālah (The Treatise) argued that Islamic philosophy should be based only on Islamic ʾuṣūl: ‘sources’ or ‘roots’ of knowledge. For al-Shāfiʿī, the Qurʾān, sunnah and ḥadīth (the records of Muhammad’s words, deeds and teachings) were the only legitimate ground or burhān (‘proof’) of knowledge. As a result of this ‘usulisation’, falsafa and ḥikmat – whether more adventurously rational or concerned with spiritual wayfaring – were marginalised because they were grounded in non-Islamic sources.

The debate between kalām and ḥikmat shifted throughout the centuries in response to changing political and intellectual developments, veering between rivalry and rapprochement. By necessity, proponents of each school became experts in the ‘other’ discipline, resulting in many hybrid works. But the division is neatly encapsulated in perhaps the most famous exchange in Islamic philosophy. Abū Hāmid al-Ghazzālī’s (1058-1126) Tahāfut al-Falāsifah (The Incoherence of the Philosophers) launched a polemical attack on the metaphysics of the falsafa tradition, above all the work of Ibn Sīnā and al-Fārābī, and argued for the priority of faith over reason. In turn, the Andalusian polymath Ibn Rushd (1126-98, known in the West as Averröes or simply ‘The Commentator of Aristotle’) responded with Tahāfut al-Tahāfut (The Incoherence of the Incoherence), a cheeky play on the title of al-Ghazzālī’s work. Ibn Rushd defended the use of Aristotelian philosophy and ijtihād (independent reason) and argued for a synthesis with Islam, thus influencing the later medieval Christian preoccupation with reconciling Aristotelian metaphysics and natural philosophy with the Bible.

By the time Ṣadrā was born into a courtly family in Shiraz in 1571, Persian philosophy was dominated by the School of Illumination based on the teachings of Suhrawardī, and the philosophical kalām of Naṣīr al-Dīn al-Ṭūsī (d. 1274). Ṣadrā’s life spanned the reign of two of the most important Safavid rulers, Shāh ʿAbbās I (reigned 1587-1629) and Shāh Ṣafī (reigned 1629-42). The Safavids oversaw a period of remarkable cultural efflorescence in which Twelver Shīʿah Islam – made the official religion of the Persian empire in the early 16th century by the dynasty’s founder, Shāh Ismāʿīl I – became the wellspring of philosophical, theological, gnostical and mystical works in the Islamic world. Indeed, the association between Shīʿah Islam and philosophy was established, given that ʿAlī ibn Abī Ṭālib, the cousin, son-in-law and (according to the Shīʿah) rightful successor to Muhammad, pioneered both kalām and spiritual wayfaring.

After receiving his initial education from his father, Ṣadrā moved first to Qazvin and then onto Isfahan in central Persia. Under the tutelage of the great scholar Mīr Dāmād, the leading intellectual light of Safavid Persia at that time and the founder of the School of Isfahan, Ṣadrā studied philosophy, theology, ḥadīth, Illuminationism, Ibn Sīnā’s Peripatetic philosophy, and the Theology of Aristotle, a ninth-century Arabic interpretation of Plotinus’ third-century Six Enneads (but then thought to be by Aristotle). Ṣadrā’s career was far from smooth, however. He returned to Shiraz but failed to find patronage. Seeking deeper insights into reality, he retreated for five years to the village of Kahak near the holy city of Qom for a period of intense meditation and wayfaring, which formed the basis of Asfār. Ṣadrā resumed his travels, maintaining a lifelong correspondence with Mīr Dāmād (despite rejecting his tutor’s argument for the primacy of essences) and teaching students who became influential philosophers and poets in their own right, such as Mullā Muḥsin Fayḍ al-Kashānī (1598–1679) and ʿAbd-Al-Razzāq Lāhījī (d. c. 1662). In 1630, Ṣadrā returned to settle in Shiraz to teach at the Madrasa-ye Khan, earning renown as a scholar, educator and philosopher. He died in Basra during his seventh pilgrimage to Mecca.

The genius of Ṣadrā’s work was to interlock the doctrinal rigour of kalām with the more speculative and mystical insights of illumination (ishrāq) and the esoteric and elliptical wisdom of gnosis (‘irfān), and to combine the rationalism of the Peripatetic Aristotelian tradition with the Neoplatonic exploration of hidden higher realities. Yet Ṣadrā still came into conflict with the practitioners of kalām (mutakallimūn) throughout his career. He criticised them, for instance, in Si aṣl (Three Principles) for ‘wear[ing] the dress of deception and hypocrisy and the robe of trickery’. Ṣadrā maintained that ‘the way to reach certainty (yaqīn) in the inquiry into religious truths and the inner meanings of the teachings of the Prophet … is not through discussions of kalām and disputations’. Instead, Ṣadrā argued, truth must be pursued ‘through the acquiring of inner and intuitive knowledge’ and ‘the rejection of worldly and base things’. Such asceticism is no accident but forms a major part of Ṣadrā’s ‘transcendent philosophy’, in harmony with the Shīʿī focus on the esoteric (inner, spiritual knowledge known only to the enlightened or illuminated few) rather than the exoteric (outer, worldly, everyday kinds of knowledge).

Ṣadrā thought that disputations about kalām and fiqh (jurisprudence), ‘whose origin is the desire for fame and social prestige’ and ‘to rule and control the servants of god’, were exoteric because worldly and materialistic. Asceticism is key to truth, then, because a rejection of earthly pleasures, powers and fame paves the way for the unalloyed spiritual and metaphysical reflection necessary to attain esoteric knowledge. The philosopher cannot embark on spiritual wayfaring if they are weighed down by the impurities and vanities of worldly concerns. Yet the historian of Islamic philosophy Cécile Bonmariage points out that ‘Pure inspirations are not Ṣadrā’s goal’. Ṣadrā himself says in Shawāhid that the wayfarer is akin to a deep-sea diver bringing ‘pearls’ from ‘the bottom of wisdom’s sea to the shore of demonstrative exposition’. One of his key insights, then, is that the pursuit of truth must unite reason and revelation, intellect and illumination, sapientia and spirituality.

It is difficult to overstate Ṣadrā’s impact on Islamic philosophy and the intellectual culture of the Muslim world, especially in Shīʿī circles. Nasr says that ‘kalām soon became eclipsed completely in Persia with the revival of ḥikmah, especially of the school of Mullā Ṣadrā’, who is ‘without doubt the greatest of the later Islamic philosophers and perhaps the most outstanding among all Islamic philosophers in the field of metaphysics’. Nor did Ṣadrā’s influence wane after the expiration of the Safavid dynasty, for he profoundly influenced Hādī Sabzavārī (1797-1873), the most renowned philosopher of the Qajar period. And, as Amjad Naqavi, Dean of The Shīʿah Institute in London, notes in his 2015 translation of Ayatollah Ruhollah Khomeini’s Sirr al-ṣalat (The Mystery of Prayer), the leader of the Iranian Revolution was steeped in Ṣadrā’s Asfār and took ‘spiritual wayfaring towards the divine’ as a central organising principle of his thought.

There are also resonant connections between Ṣadrā and Western philosophy. In his Discourse on Metaphysics (1686), Gottfried Leibniz argued ‘created substances depend upon God, who preserves them and who even produces them continually by a kind of emanation’, echoing Ṣadrā’s account in Asfār of the emanation and modulation of existence from the Necessary Being. Ṣadrā’s attempt to forge a comprehensive system of ontology and metaphysics grounded in the concept of wujūd also anticipated Martin Heidegger’s Being and Time (1927). In exploring the meaning of being and confronting the problem that being is at once the most universal and self-evident and yet paradoxically indefinable concept, Heidegger took up Ṣadrā’s mantle and the long tradition of the philosophy of existence (wujūd) that shaped Islamic philosophy from the classical period onwards.

Ṣadrā’s contribution to Islamic philosophy and global intellectual history is profound. He is slowly being recognised in the West, yet deserves far more attention from general readers outside the Muslim world.