Hume Enquiry Concerning Human Understanding

David Hume, in the fifth section of his work entitled, An Enquiry Concerning Human Understanding, dismisses the concept that reasoning is the foundation upon which conclusions are necessarily drawn. As an empiricist, Hume believed that it was essential that individuals obtain knowledge based upon their own experience and observations. He classified knowledge into two types: the relations between ideas and matters of fact. In Hume's mind, mathematics is the classic example of a relations of ideas type knowledge. This is the only form of reasoning that has complete certainty. He considered such knowledge as being a priori while the other style of knowledge, matter of facts, was a posteriori. Relations of ideas are true by definition or logic while matters of fact must be learned and tested by one's senses.

The essence of matter of fact knowledge is the process of observation and employing induction and probability. Acquiring this knowledge is dependent on one's experience in the present and what one can remember of these experiences. On the basis of one's past experience where the cause is repeatedly followed by the effect individuals begin to infer the effect whenever we experience the cause. The inference is drawn without reasoning and without any argument in a process that Hume describes as habit or custom.

Hume's classic example is the universal belief that the sun will always rise tomorrow. This is a viewed by everyone as a matter of fact. People have always believed that the sun came up every morning. It was not a certainty but it was probable. It became to be viewed as such through past observations. There was no rational basis for it but mankind believed it. This is the essence of matter of fact knowledge. The sun has always come up every morning and, therefore, there is a strong likelihood that it will happen tomorrow but it cannot be assumed that it is categorically true because there is a possibility that it might not. Experience tells us otherwise but there remains a chance.

Hume, however, is quick to point out that claiming that the sun will rise tomorrow is neither true nor false. As humans we use the process of induction to predict what will occur in the future and we use this process to predict that the sun will rise tomorrow but this habit of thinking occurs without our having any basis of actual truth to make this justification and just because it has happened in the past does not guarantee that it will rise tomorrow.

Hume believed that all reasoning concerning matters of fact, such as the sun rising in the morning, was based on the relationship between cause and effect but that even though the cause preceded the effect there is no proof that the cause is responsible for the effect's occurrence. In Hume's thinking, the effect could be purely coincidental. As an empiricist, Hume was well versed in its theoretical basis, and he did not believe that cause and effect could be proven through the use of scientific methodology but was, instead, based on reasonable probability that is reinforced through continuous reinforcement.This continuous reinforcement results in habits that are associations of one's distinct impressions or experiences. These impressions are derived as events that one observes from the outside world are, eventually, through repetition, incorporated into one's mind.

Hume's entire philosophy is based upon a healthy exercise of skepticism. According to Hume there is no certainty, no self-evident knowledge of anything. What is available is only a probability. There is no certainty. Particular causes may not always produce the same particular results. Everything is subject to doubt.

The skepticism that is inherent in Hume's philosophy disallows individuals from speculating beyond the limits of their present experience and memory. Our present experience and memory allow us to infer what might occur in the future given what has occurred in the past but there is no certainty.

In the example of the discovery of Humeum Hume would approach such situation with his required skepticism. The isolated incident of the Humeum's melting at 100 degrees Celsius would not cause Hume to view it necessarily likely that in future situation that the Hemeum would melt at the same temperature. It would only be through repetition that Hume would allow such an occurrence would develop into a matter of fact similar to the sun rising in the morning. Hume would treat the initial occurrence as being isolated and subject to contrary results in the future. Once the same procedure, however, had been on a number of occasions with the same result, however, the effects of repetition would take over and a habit or custom would necessarily develop relative to the melting of the Hemeum. This habit or custom would cause one to anticipate the melting with little thought as to its occurrence. It would then enter the realm of occurrences in life that are considered matters of fact. Prior to its being incorporated into one's mind as a matter of fact, however, an observer can rely upon the one prior experience to determine that Hemeum is likely to melt again at 100° Celsius. Until such time as a contrary result is observed, the observer has good cause to believe that it will occur precisely as he observed earlier. There remains, however, the possibility that a contrary result may occur.