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Knowledge and the Physical World
Among philosophers a common matter of study has been the extent of knowledge as well as the methods by which it can be obtained. In order to begin the process of studying knowledge it is necessary to know what knowledge is. For example; to address the question: “Can it be known that trees exist?” it is important to understand what it means to know. In this paper I will first define knowledge, then I will introduce the ideas of four philosophers, who spent a great deal of time on the subject of knowledge, and I will use that information to address the existence of trees; I will finish by showing that according to the presented information trees exist in a physical world beyond the confines of the mind.
When first approaching the topic of knowledge it is best to discern what knowledge entails; according to Brigham Young University Professor Chris Foster “knowledge is belief that is justified by sound reasoning”. Beyond Professor Foster’s definition, knowledge is also the organization and structure of ideas that are used to determine said beliefs. For the purpose of this paper I will briefly address the studies of Rene Descartes, David Hume, Immanuel Kant, and George Berkeley on the subject of knowledge and their application of knowledge to the existence of a physical world that exists outside the mind. Following the information that I have gathered, I will conclude the paper by supporting my thesis and addressing any objections that may arise.
In the 17th century Rene Descartes began the “Meditations on First Philosophy” which led to the phrase “I think; therefore I am”. In his meditations Descartes approaches the subject of knowledge by first taking the stand of a skeptic. By doing so Descartes initially denies everything that has space for doubt. In the area of doubt Descartes denies everything that he has learned from his senses because his senses have deceived him in the past. By denying that he has a body Descartes leads into the possibility that nothing in nature exists and that everything is but a dream, or a fairy tale created by an evil genius. In his meditations Descartes uses the existence of God to refute the evil genius possibility; in order to refute the dream theory Descartes says that he knows that he is not dreaming when he is able to connect his memories along a sequence of time. By removing these sections of doubt Descartes takes a foundational approach and begins to build his knowledge upon the fact that he is able to doubt and to think.
Once Descartes determines that he exists, he is able to follow a succession of thoughts that connect his mind to his body, and his body to other corporeal objects in space. Through these connections Descartes suggests that the physical world does exist and can be known, but there must be certain logical reasoning applied to sense perceptions in order to determine justifiable knowledge. All of the steps that Descartes took in determining the existence of a physical world was based around the moment where as he was thinking, he was existing as a mind. After Descartes brings in the existence of his body as an extension of his mind he clarifies that the mind and body are distinct because his body can be destroyed, yet his mind will still exist. For Descartes logical reason and undeniable information are the main facets of knowledge.
The meditations by Descartes are done in six parts, and each section focuses on developing one main idea. The meditations that focus on the idea, “I think; therefore I am” have been looked at in great depth by Don Locke, who finds a great flaw in Descartes popularized statement. Locke suggests that according to Descartes’ statement when Locke ceased to think, he would also cease to exist, but Locke himself provides a solution to the flaw by saying that Descartes may have meant that there exists a thing which has the ability to think. Without the existence of the mind, and then the body, Descartes would not be able to show that through our minds we can determine the existence of physical objects beyond ourselves. While using sound reasoning the ability to perceive objects and determine their existence is possible and this idea is supported by Descartes meditations.
While Descartes was focusing on the reasoning and rationalization of the mind, in the 18th century David Hume was focusing on the conception that most knowledge is derived primarily through experience. Where Descartes was taking a foundationalist approach to determining knowledge, Hume rested entirely upon a skeptical view. Hume suggests that the only way of gaining knowledge is through experience and that reasoning in the mind has no part in determining knowledge. According to Hume all of the beliefs that a person has are based on experiences that have happened before and the belief has become a habit. Hume divides the mind into two parts: ideas and impressions. Ideas are thoughts and impressions are sensations and feelings. Hume has an empirical approach as he says that all ideas stem from impressions.
In order to make connections with ideas Hume says that it is from one of three ways: resemblance, contiguity, and cause and effect. He says that in experience provides the ideas and the mind creates the association with other ideas. Hume adds that “sense perception is a source of validity of all non-analytic knowledge” and according to Hume analytic knowledge is comprised of math and logic, whereas non-analytic knowledge encompasses everything that is not math and logic, including the corporeal world. Hume has no real conception of external objects, but he suggests that there is a continuity of objects because of the connections that the mind makes of the ideas that are caused by impressions. Even when we do not have a continued impression of the object our ideas make the connection based on similarities, thus causing the idea of “interrupted perception and continued existence.”
Hume’s ideas and impressions seem to remove the necessity of man being able to think and rationalize and reason. By suggesting that every thought is dependent upon an experience is suggesting that there is no such thing as creativity and that the imagination is simply a tool guided by relationships of ideas. Butts suggests in his article that Hume takes more of a psychological approach rather than a philosophical one, and that according to Hume’s Matter of Facts the experience that something has always occurred in the past, doesn’t imply that the experience will be repeated in the future. The example that Butts gives is the rising of the sun. Just because everyday up to and including today the sun has risen in the morning, it doesn’t mean that it will rise again tomorrow. There is no proof given in expectations and Hume cannot prove that external objects exist based on ideas from observations alone.
Immanuel Kant focuses on two parts of knowledge: a priori, which is based on inductive knowledge that hasn’t been experienced; and a posteriori, which is deductive and based on experiences. Along with these terms Kant includes the term transcendental empiricism and suggests that there are some mental representations which are non-empirical, or not based on experience. With transcendental empiricism a priori knowledge is necessary in certain cases to be able to have an entirely empirical experience of an object. This idea is very different from Hume because Hume found the experience to be necessary before the idea.
Kant also emphasizes the phenomena and the noumena of knowledge. The phenomena include the appearances that are part of an experience, and the noumena are the objects themselves that make reality. Kant focuses on a cause and effect that are different from Hume’s; in Kant’s version of cause and effect we can perceive and make judgments on the physical world based upon observable phenomena. According to Hume it would be said that the observable phenomena are all that are needed and that judgment would not be necessary. Some differences between Kant and Hume are that in the case of Kant metaphysics override experience and that “a priori knowledge [can] be acquired regardless of particular sensory experiences, just so long as they [are] sufficient for the knower to attain the relevant concepts.”
An important factor to keep in mind while studying Kant is that he says that knowledge is limited based on the structure and function of the human mind, and that the laws of nature depend on those structures and not on objects of perception. Kant also upholds his idea that all that we can know of objects is how they appear in our mind, that outside of the perception we have of them there can be no knowledge. This doesn’t take away from the idea that information can be known outside of experiences, but it does suggest that of physical objects we can only know what is perceived. The things that can be known without sensory perception include matters of God and the soul, which are metaphysical and cannot be perceived. Empirical philosophers who rely on experience solely would not agree with Kant and his idea that God and the soul can exist despite the lack of sensory or perceived knowledge.