There is a distinct difference between rationalism and empiricism. In fact, they are very plainly the direct opposite of each other. Rationalism is the belief in innate ideas, reason, and deduction. Empiricism is the belief in sense perception, induction, and that there are no innate ideas.
With rationalism, believing in innate ideas means to have ideas before we are born.-for example, through reincarnation. Plato best explains this through his theory of the forms, which is the place where everyone goes and attains knowledge before they are taken back to the “visible world”. Innate ideas can explain why some people are just naturally better at some things than other people are- even if they have had the same experiences.
Believing that reason is the main source of knowledge is another clear distinction of rationalism. Rationalists believe that the 5 senses only give you opinions, not reasons. For example, in Descartes’ wax argument, he explains how a candle has one shape to begin with- but once the candle is lit, it begins to melt, lose its fragrance, and take on a completely different shape than it had started with. This argument proves that our senses can be deceiving and that they should not be trusted.
Deduction is the third characteristic of rationalism, which is to prove something with certainty rather than reason. For example, Descartes attempted to prove the existence of God through deductive reasoning in his third meditation. It went something like this: “I have an idea of a perfect substance, but I am not a perfect substance, so there is no way I could not be the cause of this idea, so there must be some formal reality which is a perfect substance- like God. Because only perfection can create perfection, and though it can also create imperfection- nothing that is imperfect can create something that is perfect.
Unlike rationalists, empiricists believe that sense perception is the main source of knowledge. John Locke explained this by dividing ideas into 2 parts: 1) simple, and 2) complex. Simple ideas are based only on perception, like color, size, shape, etc. Complex ideas are formed when simple ideas are combined.
Another belief of empiricists is that ideas are only acquired through experience, and not through innate ideas. Empiricists reject the concept of innate knowledge because, for example, if children had this knowledge, why do they not show it? Like why does a baby need to learn to walk or talk, why does he or she not have this knowledge at birth? Lock believed that only with experiences could one form simple ideas, which could then be combined into complex ideas.