Hume's Analysis and Skepticism of Causality
             David Hume was one of the most influential philosophers of modern times. Hume argued that man gains knowledge through experience and that we should be skeptical of all other knowledge. Hume analyzed various aspects of life, but was probably best recognized for his theory of causality. Hume set up criteria for determining cause and effect. These criteria explained his skepticism about causality and why he came to the conclusion that humans were not capable of discovering truth.
             In order to fully understand Hume's analysis of causality, we must first understand the importance he placed on the senses. Hume is skeptical of all that is not in some way connected to our senses. Hume separated human perceptions into two distinct categories: impressions and ideas. Impressions include sensations and emotions. They are original and more forceful and lively than ideas. They are what we see, hear, feel, love or hate. Ideas are copies or reflections of impressions and are less lively than the original impression. For example, if I place my hand on a hot pan and feel the heat, I have an impression. Later, when I go over the experience in my thoughts, I may recall the heat, I may remember the burning pain, but I cannot truly experience the sensation again. That reflection upon my experience is an idea. Hume also believed that there are simple and complex impressions and ideas. The impression of the color red, for example, is simple. Whereas a red cup can be separated into parts and is therefore is complex. Simple and complex ideas are always derived from simple impressions. Hume thought that because of this, there are no innate ideas, and that all ideas must come from experience, and therefore relies on our senses. If humans were to have no senses they would have no thoughts of any nature.
             The principle that all simple ideas derive from simple impressions plays an i...