The Islamic Scholar who Influenced Jewish and Christian Thought

Chapter 1: Introduction

The Islamic Golden Age (c. 750-1258 BCE) was marked by significant cultural, religious, scientific, and technological developments in the Muslim world (Abbas, 2011, p. 9).

It was during the Islamic Golden Age that the physician and philosopher Avicenna argued for the existence of God. In The Metaphysics of the Healing, Remarks and Admonitions: Physics and Metaphysics, and Salvation (Adamson, 2016, pp. 459–460), Avicenna argued for the existence of a being that possesses the exact same attributes as God, including, but not limited to, necessity, uniqueness, simplicity, ineffability, intellection, and goodness (Adamson, 2013, p. 177). His argument would subsequently be taken up not just by generations of Muslim philosophers and theologians, but also by Jewish philosophers like Maimonides, and Christian philosophers like Duns Scotus (p. 170).

In this article, I introduce Avicenna, his argument for the existence of God, and his influence on Jewish and Christian thought.

Chapter 2: Avicenna

Avicenna was a Persian philosopher and physician who lived between 980 and 1037 CE duing the Islamic Golden Age (Adamson, 2013, pp. 7–27). Born in Bukhara in modern Uzbekistan, Avicenna was a prolific writer, authoring some 450 books on a wide range of topics including, but not limited to, philosophy, medicine, astronomy, mathematics and theology (Critchley, 2009, pp. 86–87). His most famous works include The Metaphysics of the Healing, a philosophical encyclopaedia which covers all aspects of Aristotlean philosophy (Gutas, 2016), and the Canon of Medicine, a medical encyclopaedia which remained as the standard medical textbook in Europe for seven centuries (Critchley, 2008, p. 86).

As a physician, Avicenna emphasised the importance of anatomy and physiology in the diagnosis and the treatment of diseases (Adamson, 2013, pp. 91–108). And, as a philosopher, Avicenna argued, in The Metaphysics of the Healing, Remarks and Admonitions: Physics and Metaphysics, and Salvation, for the existence of God (Adamson, 2016, pp. 459–460)

In what follows, I outline his argument for the existence of God as it was presented, in arguably its most concise form, in Remarks and Admonitions: Physics and Metaphysics (Avicenna, n.d./2014).

Chapter 3: Avicenna’s Argument

To argue for the existence of God, Avicenna started with an argument for a necessary existent. In other words, for something that not just exists, but necessarily so. The complete proof can be found in the Appendix, although its outline is as follows:

All existents are either necessary or contingent.
All contingent existents have a cause, none of which is itself.
The set of all contingent existents is a contingent existent.
The cause of the set of all contingent existents is a necessary existent.
There is a necessary existent.

Avicenna begins his argument with the distinction between necessary and contingent existents, the latter being neither necessary nor impossible (Avicenna, n.d./ 2014, 4:9). Next, Avicenna proceeds to argue that, although all contingent existents have a cause, none of these causes are itself (4:10). Then, he turns our attention to the set of all contingent existents, arguing that the set must also be contingent (4:11), and that its cause must be necessary (4:15). Therefore, there must be a necessary existent, as was to be demonstrated.

Having proved the existence of a necessary being, Avicenna argues that such a being must possess the exact same attributes as God, including, but not limited to, necessity, uniqueness, simplicity, ineffability, intellection, and goodness (Adamson, 2013, pp. 170–189; Avicenna, n.d./2014, 4:18–29). Therefore, God must exist.

This argument is elegant. And, as we will see, it had a profound influence on both Jewish and Christian thinkers during the Medieval and Rennaissance period.

Chapter 4: Avicenna’s Influence on Jewish and Christian Thought

Avicenna’s argument for the existence of God, as well as his other ideas, had a significant but often indirect influence on Jewish philosophers like Maimonides, and Christian philosophers like Duns Scotus (Adamson, 2013, p. 2).

On the one hand, Maimonides (1135-1204 CE) was a Jewish philosopher and physician who is considered to be one of the most important Jewish thinkers of all time (Halbertal, 2014). Avicenna’s influence on Maimonides is evident in many areas of their thought, including their views on astrology (Harvey, 2019), and the nature of God (Pessin, 2014).

On the other hand, Duns Scotus (1266-1308 CE) was a Christian philosopher and theologian (Williams, 2019). He is considered to be one of the four most important Christian philosopher-theologians of Western Europe in the High Middle Ages, together with Thomas Aquinas, Bonadventure, and William of Ockham (Hause, n.d.). Avicenna’s influence on Duns Scotus was profound, especially in the area of metaphysics (OUP Philosophy Team, 2019).

Chapter 5: Conclusion

In this article, we have been introduced to Avicenna, his argument for the existence of God, and his influence on Jewish and Christian thought. In particular, we saw how a medieval scholar argued for a necessary existent which possesses the exact same attributes as God, such as necessity, uniqueness, simplicity, ineffability, intellection, and goodness, and how his argument had a profound influence on subsequent Jewish and Christian thinkers, such as Maimonides and Duns Scotus.

More significantly, Avicenna’s influence on these thinkers is a testament to the importance of cross-cultural dialogue and intellectual exchange. Both Maimonides and Duns Scotus were able to learn from Avicenna and other Islamic philosophers, despite their different religious backgrounds. It was precisely this free exchange of ideas that helped to enrich these thinkers’ own thoughts and make them one of the most important thinkers in intellectual history in their own right.

Appendix

Theorem 1. All existents are either necessary or contingent (i.e., neither necessary nor impossible).

Proof. All existents exist. Because all existents exist, all existents are possible. And because all existents are either necessary or not necessary, all existents are both possible and either necessary or not necessary. In other words, all existents are either both necessary and possible or both not necessary and possible. Because all existents are both necessary and possible if and only if they are necessary, all existents are either necessary or both not necessary and possible. In other words, all existents are either necessary or contingent (i.e., neither necessary not impossible).

Theorem 2. All contingent existents have a cause, none of which is itself.

Proof. By the Principle of Sufficient Reason, all existents have a cause. If an existent is necessary, then its necessity can be a cause for its existence. After all, it is implied in the statement that “x is necessary” that x exists. However, if an existent is contingent, then it is not necessary, and its contingency cannot be a cause for its existence. After all, it is not implied in the statement that “x is neither necessary nor impossible” that x exists. Therefore, all contingent existents have a cause, none of which is itself.

Theorem 3. The set of all contingent existents is a contingent existent.

Proof. Suppose that the set of all contingent existents is necessary existent. Then all contingent existents are necessary existents. After all, the set of all contingent existents cannot be guaranteed to exist if some of its elements are not necessary. In other words, all existents that are not necessary are necessary. However, this is absurd. Therefore, the set of all contingent existents is a contingent existent.

Corollary 1. The set of all contingent existents has a cause.

Proof. By Theorem 2, the set of all contingent existents has a cause.

Lemma 1. A cause of the set of all contingent existents is a cause of each contingent existent.

Proof. The set of all contingent existents is a cause of each contingent existent. Therefore, a cause of the set of all contingent existents is also a cause of each contingent existent.

Theorem 4. A cause of the set of all contingent existents is a necessary existent.

Proof. Suppose that a cause of the set of all contingent existents is not a necessary existent. In other words, it is a contingent existent. Then the cause of the set of all contingent existents is an element of the set of all contingent existents. By Lemma 1, it is a cause of itself. However, by Theorem 2, this is absurd. Therefore, a cause of the set of all contingent existents is a necessary existent.

Theorem 5. There is a necessary existent.

Proof. Theorem 5 follows from Corollary 1 and Theorem 4.

References

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Adamson, P. (2016). Philosophy in the Islamic World: A history of philosophy without any gaps, Volume 3. Oxford University Press.

Avicenna. (2014). Remarks and Admonitions: Physics and Metaphysics. (S. Inati, Trans.). Columbia University Press. (Original work n.d.).

Critchley, S. (2009). The book of dead philosophers. Vintage.

Gutas, D. (2016). Ibn Sina [Avicenna]. In The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.

Halbertal, M. (2013). Maimonides: Life and thought. Princeton University.

Harvey, E. (2019). Avicenna’s influence on Maimonides’ “epistle on astrology”. Arabic Sciences and Philosophy, 29(2), 171–183.

Hause, J. (n.d.). John Duns Scotus. Internet Encyclopedia of Philosophy. https://iep.utm.edu/john-duns-scotus/

OUP Philosophy Team. (2019). John Duns Scotus — The ‘Subtle Doctor’ — Philosopher of the Month. Oxford University Press Blog. https://blog.oup.com/2019/09/john-duns-scotus-the-subtle-doctor-philosopher-of-the-month/

Pessin, S. (2016). The Influence of Islamic Thought on Maimonides. In The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.

Williams, T. (2022). John Duns Scotus. In The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.