Plato and Descartes were among the first to claim that the development of scientific theory does not minimize the importance of other theories dealing with the visible world. However, even the visible world can never be fully understood. The certain knowledge deals with the world of pure ideas, the world that never changes. However, if “there is really a certain knowledge, it does not appear to be required for the ordinary purpose of life, nor does it even seem to be sought by people in the quest for answers to their questions” (Popkin and Stroll, p. 205). Therefore, instead of seeking absolutely certain knowledge about the real world, Locke and other philosophers tried to discover how people get information and whether this information is reliable. Empiricism is a theory that attempts to explain human knowledge in terms of sense experience.
The quest for absolute knowledge is fruitless because not a single person is able to claim with certainty that the specific idea or knowledge is absolute. I agree with Locke that knowledge comes to humans through their senses and that not a single person has innate ideas. Our knowledge is built from different experiences starting from the simple sense awareness to the compounds of qualities. There are no ideas or principles that are independent to our sense experience. When people examine any information, they discover that they do not possess innate knowledge. Any idea is the result of sense experience. From Locke’s perspective, the human mind is originally a white paper. Humans are born without observations or experience; knowledge is gained. All things and knowledge come from experience; all information is based on experience.
Information is gained either from experiences of reflections or of sensations. Simple ideas, as Locke argued, are the basic elements of knowledge that are not compounded of any other elements. Further, sensations can be classified as ideas of primary qualities and ideas of secondary qualities. Primary qualities, in particular, are items in experience that belong to objects humans are experiencing. Secondary qualities, on the contrary, are in objects themselves. Locke explained that when people observe several simple ideas appearing together regularly or conjointly, they assume that these ideas belong to one thing. Knowledge is the result of examination of ideas to see whether they agree/disagree in any respect. Thus, people compare diverse ideas to see if they are identical or different.
However, no one can be assured in ideas or knowledge. According to Locke, the greatest degree of assurance is when knowledge is intuitive. By looking at two ideas, for example, people can see immediately that something is true about them. Moreover, when people consider some ideas together, it is hard to tell if they have something in common. Sometimes it is necessary to connect the ideas to others of our knowledge. Locke defined this process as demonstration. Sensitive knowledge assures people of the actual existence of specific things. Locke argued that humans can know about those matters of which they can have ideas because knowledge is limited. “By means of sensitive knowledge, we can be sure only of the existence outside of us of some of the ideas immediately present to the mind” (Popkin and Stroll, p. 211). Since the knowledge is limited, science is not possible for either the physical world or the spiritual world because all of the information is restricted to empirical elements acquired from sensation or reflection.
Finally, even with the limited information gained from experience, people have some foundation for claiming that they know something about what goes outside of human minds. Knowledge of the own ideas is more than just imagination; there is a conformity between ideas and real nature of things. All simple ideas represent something real; the mind is incapable of inventing simple ideas because they cannot be formed from any other ideas that people already possess.