Berkeley was an Irish philosopher born in 1685 in Kilkenny, Ireland. He is best known for arguing that the existence of the material world is an assumption, and that it is possible that matter does not exist. Instead, he puts forth the notion that the world is simply a collection of ideas that are constantly being contemplated by the “mind of God.” This bizarre idealism (the belief that the world is made up of ideas rather than material things) was rooted in his desire to defend Christian doctrine against the new “atheist Materialism” which had emerged in the 17th century. Berkeley was concerned with the scientists, mathematicians, critical philosophers, and “freethinking” of the time, and hoped to use reason to undermine the advances of both philosophy and science. Berkeley was also an empiricist, since he used Locke‘s belief that all knowledge comes through the senses as his starting point for denying the existence of the material world.
A firm believer in Christianity, Berkeley recognized that the various “materialistic” philosophies being put forth in Europe in the 17th century were causing many people to become skeptical of Christianity. Gassendi and Hobbes reduced the world to atoms and bodies in motion, meanwhile Diderot put forth an explanation of animal behavior based on internal physical process. These “materialistic” world views did not have much place for things like God or Angels. The French philosopher Juliden de la Mettrie went even further, explaining man as a “machine.” Being able to explain man’s functions in purely physical terms, la Mettrie’s system had no need to understand man as having a soul. Recognizing how these materialist philosophies were undermining the fundamental tenants of Christian faith, Berkeley sought to defend the Church by attacking materialism.
Berkeley found the starting point for his simultaneous defense of Christianity and attack of materialism, and the atheism which it had breed, in Locke’s empirical philosophy. Locke explained that our knowledge comes from sensory experience. Locke pointed out that our understanding of the world is an understanding of appearances, rather than it’s fundamental essence. Specifically, Locke says that things such as color and taste (what he calls “secondary qualities”) are caused by things such as solidity and extension (“primary qualities”), which exist in the things themselves. Although we are unable to have knowledge of these primary qualities, since we can only experience the secondary qualities which they produce, Locke assumes on the basis of common sense that these primary qualities exist in some form of substance i.e. matter.
Desiring to attack materialism, Berkeley asks why we should assume that there is any substance which has these primary qualities in the first place? How do I know a table actually exists as a material thing if I only know it on the basis of my perception of the secondary qualities such as it’s color or feel? Berkeley points out that there is no reason to grant this assumption, and as a Christian philosopher, he decides to offer a unique alternative. Berkeley says that material objects don’t exist. The only thing that exists is ideas. Famously, he writes “to be is to be perceived” (esse est percipi). Since we only know something based on our perception of it, Berkeley therefore concludes that our perceptions are the only thing that can truly be said to exist.
Berkeley explains, instead of assuming the existence of a material substance, let’s assume that the things which we perceive in our minds are simply the contents of the “mind of God.” All images are held in God’s mind, the Eternal Perceiver, which we are simply given access to. Berkeley explains that this is just as much an assumption, and therefore just as rational a belief, as the belief that material substance exists considering we cannot help but be trapped in our own “mental prisons,” knowing the appearance of things but not their ultimate cause. This view of the world as only being comprised of immaterial objects (i.e. minds: Gods and our own), is an intentionally extreme form of idealism. Berkeley was being intentionally polemical (i.e. argumentative), in order to show those who proclaim reason and atheism to go hand in hand that reason could be used both to undermine as well as support their convictions.
Berkeley’s idealistic understanding of the world challenged his contemporaries to offer a response. He was accused of “sophistry” for his attempt to rationally argue for what is contrary to common sense, and his friend Samuel Johnson explained that while Berkeley’s doctrine must be false, “it is impossible to refute it.” Johnson therefore is said to have kicked a large stone, exclaiming “I refute it thus!” Unfortunately, in doing so, he was only confirming Berkeley’s point. By kicking the stone, he experienced pain in his foot. However, based on this experience alone he could never know whether the ultimate cause of it was material, or if it just appeared to be.
In his quest to attack materialism, Berkeley attacked not only philosophy but also science and mathematics. He believed scientists overstepped their boundaries when they want beyond merely describing things, and instead postulated “real” principles such as gravity, force, and other such powers. Berkeley explained that these things are not “real,” but are simply words which help to understand consistent patterns in the appearances of things. Likewise, numbers are not “real” nor are equations. Numbers are mental constructs, and the equation 2 + 3 = 5 is simply a useful idea.
In this way, Berkeley was responding to the Scholastic belief that abstract ideas are real. As Locke explained, likewise Berkeley points out that abstractions are simply concepts created by the mind to stand for things in general. The truth, however, is that abstractions do not “exist.” Only particular things exist. “Man” does not exist, only particular men such as Tom or Frank. Likewise, a triangle or square does not exist. It is a mental construct or idea used to symbolize a thing with a particular set of features.
Berkeley in particular wanted to attack Newton’s physics and calculus. First, he explains that the concept of absolute space is absurd. Space is not a “thing,” but rather a mental construct which allows us to understand the relationship between different “things” which we perceive. Likewise, Berkeley criticizes time as an abstraction. Time is simply our experience of continuity. Further, Berkeley points out the relativity of motion. He explains that any object viewed individually would not seem to move. Motion only seems to exist when we look at things in relation to other things. Motion is therefore also a mental construct. The same thing is true of distance. What we really see are two-dimensional images, however mentally we re-create the experience in three-dimensions because of the practical value it affords us.
In presenting an idealistic worldview that is at complete odds with common sense, yet is based on logical argumentation, Berkeley sought to undermine the materialism which had taken hold of European philosophers, scientists, mathematicians, and “free-thinkers.” Berkeley took up reason in order to attack those who relied on materialism as the basis for their skeptical and atheistic attacks on Christian belief. By arguing that the world is completely immaterial rather than material, Berkeley found a new home for God, angels, and the soul.