Hume’s Philosophy: Causality, Human Nature, and Knowledge
Hume’s Analysis of Ideas and Causality
According to Hume, all objects of human reason or inquiry can be naturally divided into two classes: relations of ideas and matters of fact.
Relations of Ideas
The first class encompasses the mathematical sciences. Any statement within this realm is either intuitively or demonstratively certain.
Matters of Fact
The evidence for the truth of propositions related to matters of fact is not the same as the former. Whenever it is likely, the opposite of any matter of fact never implies a contradiction. All arguments on questions of fact are based on the cause-effect relationship.
Hume’s Idea of Cause
Every idea originates from an impression. If it is impossible to assign any impression to a term, then our suspicions are confirmed, and we are authorized to reject the term in question. The idea of causality is one of these empty terms. Thus, we deny the legitimate existence of an idea of causality, even though all factual sciences rely on this idea.
Objects that we consider causes and effects are temporally contiguous, and there is a priority in what we call the cause over what we call the effect. However, these two relationships still do not provide us with the complete idea of causation. The decisive relationship regarding the causal relationship is the necessary connection.
When a natural object or event is presented for the first time, it is impossible to discover or assume, without the aid of experience, what will actually occur. Neither reason alone nor a single experience can allow us to discover any necessary connection between one fact and another. Two events occur in constant conjunction, and this authorizes us to anticipate the appearance of one based on the other. We then call the first the cause and the second the effect, and we assume that there is a connection between them.
The experience of constant conjunction between events has developed in us the idea of a necessary connection. Therefore, the idea of cause must be sought in the peculiar circumstances that are present in constant experience, which are absent in a unique experience.
From the repetition of similar experiences, a habit appears that leads our minds to expect the corresponding fact and believe that it will occur. That is, we feel in our minds a connection between the facts, a propensity to move from one to the other.
The connection is not necessary, but it is produced by experience in our minds.
The idea of cause, therefore, does not have a basis in the ontological nature of things but rather a psychological basis in the nature (habit) of our mind.
Hume on Human Nature and Knowledge
Hume’s knowledge of human nature must be based on empirical data, the experimental method, observation, and experience. It must adhere strictly to the data as presented through introspection and the observation of life and human conduct. This involves an investigation of psychological processes and human behavior to uncover their principles and causes.
Difference from Descartes
On the question of method, Hume clearly differs from the rationalist approach (Descartes), which relies on mathematics and inherent tenacity. Hume’s approach, in contrast, relies on the natural sciences.
Principles of Knowledge
- Empirical Principle: All materials of thinking are derived from our internal or external perceptions. Reason itself cannot beget anything original.
- Principle of Immanence: Nothing can be present in the mind except an image or perception. All our ideas are nothing but copies of our impressions.
- Principle of General Ideas: All abstract general ideas are individual ideas tied to a general term of association.
- Principle of Association of Ideas: Ideas are not maintained disconnected in our minds but are associated according to similarity, contiguity, and cause and effect.
- Principle of Discrimination: No idea is valid unless there exists a corresponding impression or impressions from which it is copied.
Similarities and Differences Between Impressions and Ideas
Impressions are immediate data of experience, such as sensations or passions. Ideas are copies or images of impressions.
Relationship 1: Simple ideas always correspond to simple impressions. Complex ideas may come from either complex impressions or operations on simple ideas.
Relationship 2: Impressions derived from our internal states are derived from ideas. Once an impression has ceased, a copy remains in the mind. This copy is called our idea and can produce new impressions, which are impressions of reflection.