Empiricism is the philosophy that deals with how we know things. Empiricism states that the only thing knowable is that which is discernible through our senses, such as seeing, hearing, touching, etc. Therefore, all of our understanding, all of our concepts, reflect what our senses have told us about the external world. Generally, empiricists would deny a priori knowledge (that there is knowledge which is innate). However, some empiricists grant a priori knowledge.