Ibn Sina and "The Proof of the Truthful"

posted on: Jun 26, 2024

Photo: wikimedia commons

By Luke McMahan/ Arab America Contributing Writer

There is perhaps no more significant figure to world academia from the Islamic Golden Age than Ibn Sina. A renowned intellectual in several arts and disciplines, his most significant contributions were in the subjects of medicine and philosophy. His book The Canon of Medicine (القانون في الطبّ) was a widely used medical textbook in the Middle East and Europe for over 700 years (Britannica). But in this article, I will present an example of the latter topic, his philosophical writings, and how he used logic to make sense of his faith. This proof caused great controversy among other Islamic philosophers, but I will not discuss that here, instead mainly focusing on an explanation of the proof. This is Ibn Sina’s proof for the existence of God, or what he called “the proof of the truthful.” The main source for the following material is linked here.

First, it is important to note how Ibn Sina defines God: a being whose essence is its existence. Essence is the thing-ness of the object, and existence is its physical reality. For instance, the desk I am writing on right now has desk-ness (essence) and a physical presence in front of me (existence). But why is God’s relationship of essence and existence different from any other thing? If I think of a book, maybe that book exists in the world and maybe it does not. Thus, the book’s essence is not necessarily connected to its existence; every essence either does or does not exist. In contrast, God’s very essence is the fact of God’s existence. God by nature of God’s very being must exist. Thus Ibn Sina refers to God as the necessary existent. 

But if we know that everything in the world that is and has existed actually existed, doesn’t that mean it is necessary? No, because again Ibn Sina’s definition of God is not just that God is necessary, but that God’s very being makes God exist. God is the necessary cause of God and everything else. Something else may have necessarily existed but still depends on another thing for its existence. So when I refer to necessity in the following paragraphs, it means that its essence necessitates its existence, not just that it happened to exist. In contrast, I know that the desk in front of me exists; but that does not mean the desk created itself. This leads us to the first part of Ibn Sina’s argument.

Ibn Sina begins by explaining that everything is contingent, which means that everything’s existence depends on their parts, which in turn depend on the parts of their parts. He does not mean this temporally but ontologically (referring to the nature of being of the thing). In other words, the being of the wooden desk I’m writing on depends on the individual slabs of wood forming its legs and body, which in turn are dependent on the molecules that make them up, and so on and so forth. So logically, someone can make this claim about every contingent thing that exists into infinity (this causes this, which causes this, which causes this…). But Ibn Sina wonders whether at the end of this long chain, there is a necessary existent/ cause (God), whose being does not depend on anything else. For if there was not a necessary cause, there would just be an endless string of possible things making up all of existence, and there would be no reason or cause of these things existing in the first place.

But what if the chain of all existent but contingent things is itself necessary; or in other words, despite all of its parts being contingent, the whole chain is necessary without there being God to cause it? He immediately rules this out by saying that because a contingent thing is dependent on its parts, and because the chain by itself is made up of countless contingent things, the whole thing must be contingent, and again the whole chain must have a cause.

Then he asks: what if one of these links in the chain is the thing that is necessarily existing? But because everything in the chain has its own causes, why would some contingent things be more necessary than others? No, everything in the chain is contingent; and thus the cause must be external to the chain. And because it is outside the chain of contingent things, it is not contingent but necessary. This logical work may seem tedious; but, Ibn Sina has used these proofs to determine several aspects of God’s existence.

Thus Ibn Sina has reached his conclusion: there must be a necessary existent or cause external to the endless chain of contingent things. It cannot be bound by time, space, or body. It is also indivisible and unified itself, not made up of parts. Lastly, it cannot have any similarity to anything else in existence or else, again, it would be somehow bound by that aspect and caused by it, making it contingent. This necessary cause, whose existence is its essence, is God. But how does he then incorporate this into his faith? Quite simply, Ibn Sina believes in proving not only God but also the basic Islamic concept of Tawhid (توحيد). This states that God is eternally one, singular, unified, and is the uncaused cause, all of which have been carefully shown by the above argument.

Despite providing a strong logical foundation for many aspects of Islam that come from the concept of Tawhid, this argument was still very controversial. To other Islamic philosophers, such as Al Ghazali, some aspects of Ibn Sina’s argument proved that he was an unbeliever according to other Islamic concepts of the nature of God. Regardless of the controversy over his beliefs, Ibn Sina’s “proof of the truthful” remains a very impressive logical achievement which, for over 1400 years, has been very influential to not just Islamic philosophy but theorists of other religions as well.

 Check out our Blog here!