Hume is faithful to the general principles of empiricism (that is, the "whiteboard" theory, accepting Occam's razor, denying the concept of talent, and thinking that all knowledge comes from sensory materials), but he thinks that Locke and Becker have not carried these principles through to the end.
The best way to explore Hume is to start with his distinction between two kinds of statements: the statement expressing the relationship between ideas and the statement expressing facts. (Later philosophers inherited the term invented by Kant in19th century, that is, they divided these two categories into "analysis" and "synthesis". We follow this tradition here. ) analysis proposition ("the relationship between ideas") has the following characteristics:
A. denying such a proposition will lead to self-contradiction.
B.they are natural propositions.
C. by definition, they are true.
D.they must be true
Take the sentence "All triangles have three angles" as an example:
A. If you deny it (that is, "not all triangles have three angles"), what you say is not only wrong, but also contradictory, because a figure without three angles is not a triangle.
B. this proposition is innate. You don't need to look around or measure to find it is true, you just need to understand its meaning to know it is true.
C. by definition, this proposition is correct. That is to say, given the definition of a triangle "a closed figure with three sides", we know that a triangle must (and only) have three angles. Another way of saying it is that this sentence is defined as true, that is to say, it expresses the conceptual truth, because the concept of a triangle logically contains three angles. )
D. This proposition must be true. As long as it conforms to the current English grammar, it can't be fake.
So far, these characteristics seem to be concerned by rationalists. But ... Hume added another feature to the analytical proposition:
E. It's all tautology. In other words, they are all redundant and repetitive. Predicates (such as "there are three corners") just repeat the existing meaning in the subject (such as "triangle").
Therefore, even if you have innate knowledge, it is only about your own knowledge. The innate truth never tells us anything about reality, so the dream of rationalism, that is, the knowledge deduction system composed of pure innate truth, is just an illusion. Generally speaking, analyzing truth includes definition, components of definition, mathematics and logic. Although they are all true, they just show how we relate our ideas, such as "A=A", "2+3 = 5" and "Brothers are human beings". )
The comprehensive proposition ("fact") is just the opposite of the analytical proposition in content. They must come from sensory materials (Locke's "second nature", Becker's "concept" and "feeling"). In order to test whether the sentence "Jill has a brown dog" is meaningful, we must ask whether the key concept here can be simplified to simple perception. At least we need to know what it will be like to restore sensory perception. It may prove that Jill's dog is green, or it may prove that she doesn't have a dog at all [one feature of the comprehensive proposition is that they are not necessarily true], but in the end we know what the situation is. )
In Hume's view, the real empiricist's theory holds that only analytical propositions and comprehensive propositions are meaningful. Any proposition that is neither analytical (non-tautology) nor comprehensive (its concept cannot be reduced to sensory perception) is meaningless-nothing more!
Becker's view of God ends here! Denying "God exists" (that is, "God doesn't exist") will not lead to self-contradiction. The idea of God cannot be reduced to sensory materials. The concept of God is actually meaningless. Occam's razor is here again!
But Becker believes that without the concept of God, we can't explain what keeps the center unchanged. That is to say, if there is no God, how can there be something harmonious in reality (that is, the representation of sensory matter)? Hume has to admit that it is difficult for us to answer this question from the standpoint of pure empiricism. It is difficult to answer because Hume has assumed that it is not God who connects things, but the universal law of cause and effect. Without reason, we can finally boil down the concept of reason to its own sensory materials. That is to say, there is no difference between causality and repetitive continuity in perception. (The propositions "X leads to Y" and "X occurs and then Y occurs", although they can be confirmed by the same sensory materials, they seem to have completely different meanings. Hume doesn't seem to seriously doubt the existence of causality between things in the world (in Hume's terminology, it is "inevitable connection"), but he admits that he can't provide a rational defense for causality in common sense. Although he made this huge concession, as an empiricist, it was a bad concession. After all, some people suspect that the center is different, or think that it is unreasonable for the center to remain unchanged. (soren kierkegaard, the pioneer of existentialism, carefully studied Hume's works. It is said that another early existentialist, friedrich nietzsche, was the first person who felt that Hume was a person who experienced things completely by reason. We will talk about Kierkegaard and Nietzsche later. )
What about Descartes' absolutely certain concept of "self"? Both Locke and Becquerel think it is unnecessary to criticize the concept of "self". But Hume also doubted the origin of this concept, just as he doubted the origins of knowledge of nature, God and causality. In the theory of human nature (1735), he wrote:
Some philosophers believe that we are deeply aware of the so-called self all the time, and we feel its existence and continuity, which goes beyond the proof of being convinced of its complete identity and simplicity ... As far as I am concerned, when I feel the so-called self deeply, I will always encounter one kind or another special perception, cold or hot, bright or dark, love or hate, pain or joy, and so on. At any time, I can't catch an unconscious, I can't observe anything, I can only observe one perception ... But aside from these metaphysical experts, I can boldly tell others that they are just a collection of perceptions that are connected with each other at unimaginable speed and are in eternal flow and movement, or a bunch of perceptions. Every time our eyes turn, it will definitely change our perception. Our thoughts are more changeable than our vision, and our other senses and faculties can promote this change, while the soul has no ability to remain unchanged for even a moment.
This passage is surprising. "Self" is the foundation of certainty and the central concept of Cartesian rationalism, but "self" has become an empty concept here (therefore, there is no such concept as "self"). "Self" has no continuity of experience. In fact, there is no self-experience at all. In Hume's view, this discovery made us ordinary people very disgusted, so "we invented the continued existence of sensory perception ... and acquired the concepts of soul, self and entity to cover up this change." This discovery not only hurts rationalist philosophy, but also hurts western religions and common sense itself.
Therefore, Hume's extreme empiricism failed to demonstrate the rationality of concepts such as "God", "causality" and "self". In fact, Hume's view leads to extreme skepticism, so his view seems untenable. In the process of reading Hume's works, we felt that the ground under our feet began to collapse and the center began to break. However, in the 20th century, a group of influential philosophers absorbed Hume's ideas with only minor modifications. Their thoughts are famous logical empiricism or logical positivism.