Chomsky argued that language structures we have are innate. For example, Dutch, one of the hardest languages to learn, is known without any experience. Small children are able to grammatically construct sentences that make sense.
We can see in Descartes third wave of doubt that god is a concept that we are born with. Everything that we experience is false, as we are being deceived by a malicious demon.
A priori knowledge and innate ideas are two out of three viewpoints of rationalism. The final viewpoint of rationalism is logical necessity. This is when the relationship in a sentence must be logical. For example, in order to have three things you need to have more than two. Rationalists believe that we gain our knowledge from reason and logic. For example, a ball is thrown in the air. According to a rationalist, your logic will tell you that the ball will come down and the reason for this is because the laws of gravity.
However, there are problems with a priori knowledge. These problems can be explored through Empiricism, who believe that we gain knowledge from our senses and experience. In addition, a posteriori knowledge is important. A posteriori knowledge is best defined as a proposition that is known with reference to experience. Thus, a direct challenge to rationalism. According to empiricism, a priori knowledge is not important, as it is vital to establish reasonable grounds on that we can justify proposition that is known with reference to experience. For example, when the ball is thrown in the air, according to empiricism, we know that the ball will come back down as we have experienced this action before. Another example is, in order to know that one’s next door neighbour’s door is green, you would have to physically go and see the door.
Locke, a famous empiricism, believed that as we experience life it is written down on a blank slate. This is that Locke calls tabula rasa.
Empiricist and Rationalist both contain valid arguments. However, there are some areas where the theories lack. Rationalists solve the problem of the ball coming down, as if the ball had never been thrown before, an empiricist could never know the outcome of such an event. In such a case, rationalist’s viewpoint fits more logically. On the other hand, a rationalist will not know that his neighbour’s door is green unless you actually visit the door. In such cases, empiricist’s viewpoint stands. Another problem with rationalists is that they state mathematical truths are innate. However, this cannot be the case as some sort of concept of knowledge is require before, otherwise you will not be able to know, for example, what add means and how to use this mathematical formula.
Overall, priori and posteriori knowledge can be seen as over exaggerated. This is because in the practical life, we tend to have both parts of a priori and posteriori knowledge. Rationalists and Empiricism seem to be at two extremely different ends. However, though priori knowledge has problems, it seems more feasible in the practical world, as when making inexperienced decisions, we tend to follow logical reasoning.