The Dawn of Doubting God's Existence:

It all started with Rene Descartes (day cart), the father of modern philosophy, in the 17th century. He attempted to prove the existence of God by logically arguing against doubt, also known as skepticism. He failed. Many great minds have attempted to prove or disprove the existence of God and they have all failed. Did they get close? How did they fail? The answers to these questions will help us find our own way. What follows is a discussion of just three great minds in the realm of early modern philosophy - Rene Descartes, John Locke, and George Berkeley.

RENE DESCARTES

Descartes pioneered a way of thinking called the “Method of Doubt”. Using a pseudo Euclidian method to imitate the popular science of his time, known as Geometry, he uses only the knowledge that he can be certain of to prove God’s existence. Only two proofs survive his skepticism.

The first is the Principle of Sufficient Reason, which states that every effect necessarily has a cause. From this principle he infers the second proof, the Principle of Adequate Reality, which states that every cause necessarily has a higher degree of reality than its immediate effect. In order to find the most stable starting point for the reconstruction of knowledge that cannot be doubted, he realizes his most famous argument “Cogito”; I think therefore I exist. The solidity of the statement lies in the fact that no human with a mind could ever be wrong while actively thinking the thought found in “Cogito”. When meditating on the idea of wax, he concludes that the human mind can be deceived of the corporal world’s appearance because our idea of a candle does not change as the wax changes in corporal form. Furthermore, the uncertainty of the objects of our perception is especially apparent in dream or illusion.

Descartes makes a crucial distinction here between the object that is being perceived and the act of perceiving. He argues that Cogito illustrates the essence of the mind and concludes that the act of perceiving is necessarily true although the object of a perception is still under scrutiny. He also illustrates that the “faculties of the mind,” that commit the act of perceiving, can neither be true nor false. “The act of desiring or imagining p is neither true nor false” (Thompson, 27). The objects of his understanding are especially uncertain due to the argument of illusions, like dreams or hallucinations that don’t “match up” with the corporal world. This poses the biggest problem in Descartes' argument. In order to be certain of the objects of his perception and defeat skepticism, Descartes must defeat the “evil demon” argument. How does one know that the objects of his or her perceptions are not caused by some mischeivious demonic force?

Descartes argues that the idea of God must have been caused by God. The Principle of Sufficient Reason states that nothing comes from nothing therefore the idea of God must have a cause. He uses this principle to infer the Principle of Adequate Reality which says, “There must be at least as much reality in the total efficient cause as in the effect.” This argument implies that there are degrees of reality.

The degrees of reality then can be separated into three distinct categories: the lowest being modes or properties that depend on a finite substance, the middle class is a finite substance, and the highest being the infinite substance. In order to prove that God exists, Descartes applies the Principle of Adequate Reality to the faculty of his mind that naturally attempts to assent to the idea of infinity. When Descartes applies the Principle of Adequate Reality to his specific idea of an infinite being he comes to the conclusion that the only being with a high enough degree of reality to cause such a thought is the infinite being itself - God.

Now that he is certain of God’s existence, he continues to argue that the infinite being cannot deceive us because the infinite being is necessarily benevolent. “From these considerations it is quite obvious that he cannot be a deceiver, for it is manifest by the light of nature that all fraud and deception depend on some defect" (Thompson 40). Notice that he has successfully defeated skepticism but his argument hinges on God’s essence as existence and benevolence.
Descartes’ ontological argument is as follows:

I have an idea of God, who is by definition the perfect being.
This idea of a perfect being possesses all perfections.
But existence is a perfection.
So, the idea of God must be conceived as having existence.
Therefore, God exists.

This ontological argument uses the definition of God that ascribes existence as a property of God in order to prove his existence. In this way, Descartes' entire argument is circular.

JOHN LOCKE

Locke’s famous “Tabula Rasa” argument asserts that the entirety of knowledge is constructed from the objects of perception. Whereas Descartes argued that “innate notions” are found in the mind’s action of perceiving, Locke argues that no idea is innate in a mind that starts as an “empty cabinet.” This is merely an unfortunate interpretation of Descartes' Cogito argument. Descartes does not argue that ideas are innate but merely thinking is innate, a distinction between the object of perception and the act of perceiving.

Descartes is a Rationalist that believes that he can have a proof of God using reason alone whereas Locke, as an Imperialist, believes that experience in the form of sensitive knowledge comes before our capacity of reason.

Locke’s distinction between ideas and qualities is pivotal in his metaphysics. He believes ideas to be “in the mind” whereas qualities are “in the bodies”. He believes the “primary qualities” to be essential to the existence of corporal substance whereas “secondary qualities” are observer relative and therefore uncertain. But Locke argues that primary and secondary qualities of substances are bound together with a certain “I know not what” or “metaphysical glue.”

For instance, think of a horse. Your thought may be of a horse-shaped animal that is either large or small, black or white. The shape of the animal is an example of a primary quality whereas the size or color is an example of a secondary quality. But your idea of a horse is influenced by your experiences with horses. In the same way, Locke attempts to argue that we have an idea of God because our experiences have shaped the idea into our minds.

Due to this distinction between mind and everything else, Locke's argument is snared by skepticism. The blank slate of our mind must learn of God through sensory perceptions but mind and substances are two different things. Locke fails to prove the existence of God because he cannot explain how the corporal world causes ideas, how the mind comes to learn of God.

GEORGE BERKELEY

Berkeley argues against Locke’s distinction between primary and secondary qualities using the Parity argument. The Parity argument contends that both primary and secondary qualities are observer relative. Since Locke concludes that secondary qualities are subjective, that our perceptions of secondary qualities do not “match up” with how they actually exist outside of our mind, he has no choice but to be skeptical of secondary qualities. The Parity argument is used by Berkeley to argue that Locke’s primary qualities are also skeptical because they too are observer relative since every idea held by our mind is inherently observer relative.

Berkeley’s success in defeating skepticism lies in his rejection of dualism. In Principles 7 he says, “From what has been said it follows there is not any other substance than spirit, or that which perceives.” The “Resemblance Principle” is Berkeley’s most powerful metaphysical argument for refuting dualism. This principle asserts that only ideas can cause ideas.

Using this radical idealism, Berkeley is successful in defeating skepticism at the price of defeating his own proof of God’s existence. He asserts that “esse is percipi” which he uses to prove the existence of a “Great Mind” is necessary in order for spirit to exist. Like Descartes and Locke, Berkeley is only certain of that which he clearly and distinctly perceives. He admits that he cannot be certain of anything that he cannot frame as an idea inside of his mind. But since he cannot frame the idea of infinity inside of his mind, he retreats back to a “best possible inference” that states that we can only have a “notion” of God. Berkeley’s own “Resemblance Principle” prevents him from proving that he can have an adequate idea of God because a “notion” is not an idea and therefore cannot interact with, let alone cause, the idea of God.