Hume’s Empiricism: Perceptions, Ideas, and Causality
Empiricists argue that there are no innate ideas and that all ideas come from sense experience. Hume stated that all sciences are relevant to human nature, i.e., all sciences fall under human capacities and are judged by man. The only valid approach, according to Hume, is that of Newton, but applied to the science of man.
Understanding Perceptions and Ideas
Perceptions are the contents of the mind in general and are divided into impressions, which are the immediate data of experience, and ideas, which are representations or copies of impressions in thought (images of weakened impressions). Ideas have their origin in impressions. When the mind has received impressions, they may return in two modes: memory and imagination.
The ideas of memory are stronger than those of the imagination, for memory preserves the order and manner of the originals. The imagination, however, is free to alter and subvert ideas. The qualities from which the association of ideas emerges (laws of association) are: resemblance, contiguity, and cause and effect.
Types of Knowledge and the Limits of Impressions
For Hume, there are two possible types of knowledge: the relationship of ideas (which include all propositions of mathematics, geometry, etc.). According to Hume, an idea is true if we can determine from which impression it is derived, as the limit of our knowledge is impressions. However, we take future events for granted without having the impression. According to Hume, these anticipations are based on a cause-effect relationship.
Our knowledge of future events is justified only if a necessary connection exists between what we call cause and what we call effect. But the only observable connection between facts of which we have no perception is that there is a constant succession between them. For Hume, substance is a concept that does not correspond to any impression. Ethics is of an emotivist character because it asserts that the basis of moral judgments is in feeling. The moral sense gives us a feeling of approval or disapproval of human actions.
Hume’s Critique of Causality and External Reality
Hume thought that both Descartes and some empiricist authors had based their theory of knowledge on the concept of causality without having given it prior thought. Previously, we saw how our certainty about observed facts was a subjective certainty that relied not on knowledge of the facts but on belief. This assumption was the result of the regularity with which the past presents itself, which Hume called habit or custom.
Thus, we infer facts of the future, provided that previously we had the impressions that we now link when talking about the future. Thus, we move from one impression to another, but NOT from an impression to something that has never been experienced as an impression. John Locke argued that the existence of bodies as a different reality, and external impressions, were the cause of such views. For Hume, this is trying to apply causality between something of which there is no impression (the world itself) and the impressions I have; therefore, causality could not justify the existence of a reality outside my own impressions.
Critique of God and the World
According to Hume, belief in the existence of a non-corporeal reality may be based on causality. Descartes, Locke, and Berkeley used the idea of cause to assert that God exists. They say God is responsible for the views and ideas I have, but for Hume, that is to apply causality between something that would not be an impression (God) and the impressions that I have. Therefore, one could not justify the existence of God. The criticism of these two substances (World and God) is based, as we see, on the critique of causality.
Now, if for Hume neither the world nor God are responsible for our impressions, where do they come from? However, Hume’s empiricism cannot answer this question. It simply cannot answer because doing so would go beyond its own impressions, and those are the limits of our knowledge. We have impressions; we know not whence they come.
The Dismantling of Cartesian Metaphysics
Criticism of the idea of self, along with criticism of the idea of the world and God, is the dismantling of the three foundational substances in Cartesian metaphysics. For Hume, the existence of the self as a substance, as a permanent subject of our mental acts, is not an intuition, as Descartes would have it. We only have intuition of our ideas and impressions, and none are permanent, but rather succeed each other uninterruptedly. Similarly, we never manage to “catch” the self alone, without a thought, without a will, etc. There is, therefore, no ego as a substance other than impressions and ideas, as the subject of a series of mental acts.
Phenomena and Skepticism
These three critical empiricist principles of Hume’s philosophy lead, inevitably, to phenomena and skepticism. On the one hand, impressions are the ultimate data of my knowledge, and I cannot go beyond them. Furthermore, I can never find real connections between impressions, only succession or contiguity. We know only impressions, and therefore REALITY is reduced to these, mere phenomena (that which appears or is displayed). This is the meaning of the phenomenon in Hume. And while this may serve me for daily living, from an epistemological point of view, we are committed to skepticism.