A long and rich history of philosophy reveals different beliefs concerning mind, God, and existence. Descartes and Berkley’s opinions on the relation of these ideas are worth reflection and consideration.
One can hardly ever meet a person, who heard several philosophical ideas and does not know the most famous statement in the history of philosophy “Cogito, ergo sum” or “I think, therefore I am.” This formulation is considered to be the core element of Western philosophy and Rene Descartes, the author of this sentence, is called the ‘Father and Progenitor of Modern Philosophy’ (Mannion, 2013; Kemerling, 2011).
Rene Descartes, as a rationalist, describes the nature of reality without relying on sense experience. Sensation is the owner of a deceiving character: “Seeing that our senses sometimes deceive us, I was willing to suppose that there existed nothing really such as they presented to us” (Kalntzis & Cope, 2012, p. 1).
Unfolding the nature of reality, Rene Descartes proposes to begin with the interpretation of the meaning of existence. He uses a method of radical and hypothetical doubt to arrive at the truth about the certainty of his existence. Descartes’ philosophical epistemological method suggests accepting only indubitable ideas as true, splitting every question into manageable parts, beginning the complex issues with the simplest one, and retaining the argument whole by its frequent review (Kemerling, 2011).
Descartes starts proving his existence from the skeptical point of view using radical doubt. This methodological doubt renounces every belief that can be doubted: “I ought to reject as absolutely false all opinions in regard to which I could suppose the least ground for doubt, in order to ascertain whether after that there remained in my belief that was wholly indubitable” (Kalntzis & Cope, 2012, p. 2). All further beliefs should be based on the indubitable belief. Only then they are justified. That is why, the French philosopher proposes a hypothetical doubt (dreaming and evil demon hypothesis), i.e. make all our knowledge questionable. In such a way, Descartes tries to find out one certain true belief which can be a criterion for testing other beliefs. Every notion and idea can be questioned in the world, but the mind and pondering of the thinker remains a fact. There is the judgment that his existence becomes a foundation belief for all his further proofs about the external world, God, and, mathematics. As Nquyen (2012) points out, “He one day concluded that even if he doubts he is thinking, he must exist in order to doubt; thus he concluded that he must exist, and "I think, therefore I am" was born” (p. 4).
Thus, Descartes’ rationalism, relying on a mathematical model and displaying pure reason, eradicates the distraction of information gained by senses. In such a way, the philosopher made an attempt to advance proper human knowledge through natural sciences.
Another famous phrase in the legacy of philosophy is “To be is to be perceived”, which belongs to George Berkeley, an Anglo-Irish philosopher. Propagandizing his subjective idealism, Barkley is a bright representative of empiricism, who followed John Locke and preceded David Hume (Boeree, 2000).
Berkeley claims that there are only two kinds of things: spirits, active creatures that produce and perceive ideas, and ideas, passive beings, produced and perceived by spirits. Therefore, ideas exist through perception. According to Berkeley (Yuksel, 2013), all things really exist only in the mind that perceives them. The philosopher asserts, “To be is to be perceived” (Esse est percipi). It is impossible for things to exist beyond the perception. Berkley believes that all ideas originate from the mind of God. What is happening within the mind of God, it really exists, no matter whether anybody has experienced it. Even if we are not looking at things, touching them, or listening to them, they do not disappear, they still retain in God’s mind. The tree in the forest does indeed fall if no one is there to experience it, because it is happening within the mind of God.
Idealism of Berkeley is based on the idea that perception of objects is hidden within us. Quality of the object is not part of the object, but part of our perception. An object is composed of a set of ideas that can be perceived by touch, smell, sight, or taste. All those senses are caused in the spirits of people by the spirit of God. Reality can be found only in ideas. As Boeree (2000) points out, “This is perhaps the purest, and most eloquent, version of idealism ever” (p. 6).
Both philosophers include the notion of God into their philosophical doctrines, treating Him with totally different attitude. For both, God is the cause of our ideas, but for Descartes, God is the only cause of the idea of God, and Berkley treats God as the only cause of all ideas (Yuksel, 2013).
Following Descartes thoughts, all the things preserve their existence due to the existence of God’s ideas. Descartes uses God’s existence in order to prove the existence of the physical world. The existence of God serves as the independent existence of the idea. As Yuksel (2013) states, “Since finite self cannot generate the idea of infinite being, the ideas come from somewhere, from Infinite Being himself. Descartes introduces God as a reliable warrant for our ideas about the external world or body” (p. 4). By means of God, he solves the problem of interaction between mind and body.
Berkeley keeps God at the heart of all (Boeree, 2000). He needs God to prove the existence of the material world, because all things must be perceived by Him. The philosopher believes that all ideas originate from the mind of God. According to Berkeley, our world is real because it is perceived by the eternal mind of God: “As sure, therefore, as the sensible world really exists, so sure is there an infinite omnipresent Spirit, who contains and supports it” (Boeree, 2000, p. 3).
To sum it up, both philosophers made a great contribution into the modern philosophy, trying to explain the existence of a human being, external world, mind, and God. They chose different doctrines. Rene Descartes with the help of rationalism declared to the whole world “I think, therefore I am.” George Berkeley using empiricism and developing idealism claimed “To be is to be perceived.” Both thinkers used a concept of God to get outside their own minds and prove the existence of material world.