One of the most persistent criticisms of the Christian faith is that the incarnation is impossible and involves a logical contradiction. This criticism has been around since the time of the apostles and has been raised by Jews, Muslims, ancient Greek and modern philosophers, some theological liberals, and many others. The basis of this charge is the idea that the attributes of the divine and the attributes of the human are mutually exclusive and cannot exist together in the same person or entity. The divine is eternal, omniscient, immutable, and impassible whereas the human is temporal, limited in knowledge, subject to change, and passionate.
A common but unhelpful answer that Christians sometimes give (following Kierkegaard) is that the incarnation does involve a contradiction and that true faith requires accepting such contradictions. As we have frequently pointed out in other posts this is not an acceptable solution. If Christianity involves actual contradictions then it is necessarily false because something cannot be both true and false at the same time. While our faith certainly involves believing things that we cannot fully comprehend (beyond reason) we are never asked to believe things that are irrational (against reason).
If, however, we maintain that the Christian faith is logically coherent how do we respond to the assertion that the incarnation is contradictory and therefore impossible? The most popular response, known as the Kenotic view, is to explain that Christ emptied Himself of certain divine attributes when He came as a man. The chief support for this explanation comes from an incorrect interpretation of Philippians 2:5-7.
Have this mind among yourselves, which is yours in Christ Jesus, who, though he was in the form of God, did not count equality with God a thing to be grasped, but made himself nothing [literally emptied himself], taking the form of a servant, being born in the likeness of men.
(Philippians 2:5-7 ESV)
Despite the popularity of this explanation it has some rather serious problems. If Jesus relinquished divine attributes such as omniscience, omnipotence, etc. then either He ceased to be God while on Earth or those attributes that He gave up are not necessary attributes of divinity. If Jesus wasn’t fully God then obviously Christianity is false. On the other hand, if Jesus was God but was able to give up attributes such as eternality then they are not essential to God. If this is the case then the Christian understanding of God is incorrect and Christianity is false. The Kenotic view requires either a Christ that isn’t fully divine or a God that does not have the intrinsic attributes that the Bible attributes to Him.
A much better logical defense of the incarnation is given by the philosopher Thomas V. Morris in his book The Logic of God Incarnate . We must realize that the Christian teaching is not that the infinite divine nature was encapsulated within a finite human nature (a common mischaracterization) but rather that the divine nature was united with a human nature. It is not that God laid aside His nature to become human but rather that in the Son humanity is added to the divine nature. A contradiction would arise if any of the essential properties of divinity and humanity were mutually exclusive. Morris argues that this isn’t the case.
First, Morris points out that there is a distinction between being something fully and being something merely. To be something fully is to possess all of the essential properties necessary to its being (an essential property is something that it must necessarily possess in order to be what it is). To be something merely is to possess the necessary properties to be a member of one particular class but does not possess the essential properties necessary to also belong to another class. For example, the Eiffel Tower is fully a radio broadcasting tower but it is not merely a radio broadcasting tower. It has all of the essential properties necessary to be a broadcasting tower but it also possesses other properties that give it a definitive identity as a symbol of Paris that other broadcast towers do not.
Morris then goes on to argue that the criticism of contradiction is the result of a failure to make an important distinction between common and essential properties. If something is an essential property it is necessary that all members of a particular class possess it. Common properties on the other hand are those properties that are generally possessed by any member of a particular class but are not necessary. For example, a human nature is an essential property of humans while arms are a common property. An entity without a human nature is by definition not a human but a person without arms is fully human though they lack something that is common to humans. Morris explains that just because every human possesses some property it does not follow that it is essential. He gives the example of being born within a certain number of miles from the surface of the Earth. Every human who has ever lived has been born on Earth (common property) but it is not necessary that this is the case. If a baby were born in a space station somewhere else in the solar system the child would still be a human being.
According to Morris, properties such as limited power, knowledge, and life span are common but not essential properties of humanity. If this is the case then there is no logical contradiction involved in God taking upon Himself humanity because a being that possessed all of the essential properties of both humanity and divinity would be fully divine and also fully, though not merely, human.
There are other arguments in Morris’ book that are problematic but his demonstration that the incarnation does not involve logical inconsistencies is brilliant. He shows us that there are reasonable responses to such criticisms that do not require abandoning the historical claims of the faith or a retreat into an irrational mystical faith emptied of doctrinal content. There is no reason to retreat from the faith in the face of critical arguments because they will all fail, just as they always have “for it is written, I will destroy the wisdom of the wise, and the discernment of the discerning I will thwart.” (1 Cor. 1:20).