Descartes, Locke, and Berkeley were three prestigious philosophers, all with differing thoughts about how we perceive our sensations and ideas in our reality. How we perceive our reality depends heavily on where our thoughts, ideas and sensations come from. If we think we imagine what we see and feel, then we might think everything we think exists is only in our head. If we refuse to trust our senses, then how do we know what we sense and feel really exists, and not just imagined, or placed upon us by a higher, deceptive power. Locke and Berkeley both believed that we must rely on our senses to gain knowledge, but their ideas about reality differ very much from then on out. Descartes on the other hand believes the exact opposite of those two, saying that we cannot trust our senses, and by experience alone can we find the truth of reality. Senses include everything we see, hear, taste, feel and touch. How these three philosophers perceive and embrace these senses differ greatly. Aside from senses, these three philosophers also think differently about where our ideas come from, and how we interpret them.

Descartes was a rationalist. He believed that only through reason alone, without aid from any senses, that we are capable of arriving at some explicit truths. Descartes once stated, “I have noticed that the senses are sometimes deceptive”.  He might mean that, when something is so cold, that it feels hot, or vice-versa. Descartes also stated that even though senses can be deceiving, there are some things that cannot be denied, such as existence. He thinks this because he himself can think, so therefore he must be able to exist, since he has a conscious. This revelation can be interpreted by his famous phrase, “I think, therefore I am”. Descartes believes that there is a God who created him, but how does he know that God is just having him imagine everything he sees and senses? Assuming that God is supposed to be a supremely good being, he would never take part in such deceptions. What if, instead of a supremely good being such as God, there is an evil genius that directs all his effort into deceiving him. How can he trust any external sense beyond himself? Anything beyond his own mind can be considered a deception by the evil genius, including colors, heavens, air, earth, hands, and his own body. Descartes then states that out of laziness he conforms to the genius’s illusions. He doesn’t want to be awakened into the truth, for he enjoys the dream he’s having. If any of this is true, then ultimately it proves that Descartes exists, since he must exist to be deceived. Descartes then states that even though he knows exists, how can he trust his senses to tell him what he is seeing is true, since after all, he states there might be an evil genius trying to deceive him. He states that senses can be deceiving between being awake and sleep. There are no definitive signs to prove he is awake, so how can he prove that he isn’t just dreaming everything? Considering that we are dreaming, how do we know what we see is in a dream actually exists in real life? How can we be sure we aren’t imagining our eyes, head, hands and bodies? Descartes explains that what we see in dreams are “painted images” from our reality and must reflect true things. Even things we have never seen before in dreams come from things we have seen in our waking state. These things may have just been combined with other things or distorted. Everything in our dreams comes from things we have seen or thought of in the waking state, so our hands; body etcetera must exist if they are in our dreams.

Locke’s views differed greatly compared to Descartes. In fact, his views were almost completely opposite. Locke was an Empiricist. Empiricists believe that the source of all knowledge can be found through experience. This is obviously the opposite of Descartes, since it says that we must rely on our senses and experiences as sole source of knowledge. Locke believed that when were born, we are a “white paper devoid of all characters”, on which “experience” writes. Exceptions to this statement are children and idiots, because they do not have enough thought in them. Children and idiots do not have the experience to gain knowledge, do not have the brainpower to take in the experience and turn it into knowledge. Locke explains that all ideas come from sensation and reflection. We come by senses like yellow, white, heat, soft, bitter, sweet, and reflect upon them in our minds, then understand them and gain that sense. We also gain ideas from sensations in our minds. To understand an event, we go through perception, doubting, believing, reasoning, willing, and all other types of actings within our minds, reflect upon them and recognize them. Locke says, “The mind furnishes the understanding with ideas of its own perceptions.”

The final philosopher is Berkeley. Like Locke, Berkeley is an Empiricist. Berkeley has his own philosophy, which he calls immaterialism. Berkeley has a rather unique philosophy, which states that nothing exists outside the mind. Everything that a person sees or thinks only exists in his or her mind. Whatever is thought of is an idea in the mind of the person thinking it. He states that nothing can be thought of except ideas in the minds, and anything else is inconceivable. He then further explains that what is inconceivable, cannot exist. Therefore, matter, which by definition is not an idea in the mind, cannot exist. Matter is not said to be an idea, but a material. So since matter is material and not thought of, it cannot exist, implying the fact that only things in the mind exist. Berkeley explains that the earth is not composed of both material and immaterial substances, as many other people have said. The earth is only composed of immaterial substances, or “spirit”. This idea is best termed as idealism. Idealism is the belief that reality is ultimately mental, spiritual or nonmaterial in nature, and all we know is our ideas.

So in conclusion, although both Descartes and Locke have almost exact opposite ideas, they both have certain things in common with Berkeley. Descartes and Berkeley both believe that reality is ultimately mental, and we cannot be certain that substances such as matter actually exist. Locke and Berkeley both agree on the fact that they are both empiricists, and believe that all knowledge can be found through experience. While Descartes believes that senses cannot be trusted, Locke and Berkeley both agree that we must rely on our senses to gain knowledge. While all three philosophers seem to believe in a higher power, Descartes believes that it might be an evil genius putting all his effort into deceiving him, compared to Locke and Berkeley who seem to believe in the supremely good God.