Anselm’s famous Ontological Argument has caused controversy for a thousand years among theologians, philosophers and apologists. But is it a valid argument, or merely a “charming trick” using verbal gymnastics? While the argument iself is “simple”, it is almost indescribably complex because it deals with ultimate reality – the nature of God. “Ontological” refers to the essence or nature of being. The argument for the existence of God holds that the existence of the concept of God necessarily entails the existence of God. Let that sink in.

Here is the Anselm’s Ontological Argument:

1. God is that than which nothing greater can be thought.
2. It is greater to exist in reality than only in the mind.
3. If God exists only in the mind, then something in reality is greater which is a contradiction.
4. Therefore, God necessarily exists.

Anselm claims to derive the existence of God from the concept of a Being than which no greater can be conceived. Anselm reasoned that, if such a Being fails to exist, then a greater being—namely, a being than which no greater can be conceived, and which exists—can be conceived. But this would be absurd: nothing can be greater than a Being than which no greater can be conceived. So a Being than which no greater can be conceived—i.e., God—exists.

The ontological argument if successful plays a very important role in our thinking about Christian theism. This is because while the other arguments for God’s existence establish only some of the common properties of the divine being, the ontological produces an entire set of properties. For example, if we infer that “God is a designer” from the design argument, we still don’t know for sure what the moral standing of the designer is. Is the designer morally indifferent to us? Or is this Being all good, or something else? The point is that the ontological argument fills in every good-making property in the divine Being, because each of those properties is co-constitutive of the greatest conceivable Being. In this way, the ontological argument gives us that God is good, the creator, sovereign, wise, powerful, a person, an agent, and so forth.

The ontological argument would probably be ineffective with unbelievers. But remember that apologetics also has an inward focus in the church, on believers to help solidify their faith. The ontological argument argues for a maximally great God with all constitutive properties. All other arguments focus on a single or a few attribute(s). For example, the cosmological argument presents God as the omnipotent Creator but says nothing about his moral goodness. In contrast, the ontological argument presents God with all of his attributes in all of his fullness.

The argument is a “deductive” argument, meaning that if the premises are true, then the conclusion is necessarily true. It is an “a priori” argument; it is reasoning that is independent of experience, derived from self-evident propositions or logical deduction. It is “analytic”, not based on evidence but based on the definition of God.

The ontological argument means that God cannot “not” exist. He is a therefore a “necessary” being. A necessary being must exist in order to make sense of the existence of any contingent being. The argument while “simple”, is actually quite complex. But if one takes the time to evaluate and understand the ontological argument, the necessity of God’s existence is rooted in a wealth of logical and philosophical certitude.

After wrestling with this argument for quite a while, I experienced a “Eureka” moment and it suddenly made sense. (Neuroscientists tell us that “Eureka” moments rewire the brain.) Here is a brilliant exposition of the Ontological Argument by Gavin Ortlund, PhD who is a gifted theologian, philosopher, and apologist. While lengthy, it’s worth watching in entirety.