Substance, Empiricism, and the Limits of Knowledge
Guaranteeing my ideas a reality is extramental: world, extension, and movement. The structure of the three substances of reality: God is infinite substance, thinking substance, I, and extended substance.
Concept of Substance
The substance is anything that does not need anything else to exist (you can only apply this in an absolute way to God).
Body and Soul
Descartes states that the soul, mind, and body are distinct substances. Extension is to safeguard the autonomy of the soul concerning matter.
Hume
Empiricism
English philosophy without frills, the reaction against rationalism. The source and limitation of knowledge: empiricism is characterized by a radical rejection of innatism. According to empiricists, there are no innate ideas or principles. We can define empiricism as a theory that denies the existence of innate knowledge and states that our knowledge comes from experience. From this thesis follows the restriction of our knowledge: because our knowledge comes from experience, it cannot go beyond experience, and we can only be certain about what is inside the limits of experience.
The genesis of knowledge: as our ideas proceed from experience, a central matter of philosophical empiricism will be the study of its genesis, that is, how our ideas arise from experience. The analytical method consists of taking simple ideas and studying the psychological mechanisms of the association and combination of ideas.
Theory of Knowledge and its Limits
Impressions and Ideas
Hume reserves the word “idea” to designate only certain contents of knowledge and perception. He calls the first type of perception “impressions” (known through the senses) and the second, “ideas” (copies or representations of impressions in thinking). Ideas are weaker than impressions. Ideas come from impressions; they are pictures or representations of them.
Perception: all that is present to the mind. Hume distinguishes two types of perceptions: impressions and ideas.
Impression: a perception that affects the mind with a singular force and vivacity, appearing before it in an original way through the senses.
Idea: a copy of impressions. A weak perception consists of the image of an impression.
Types of Knowledge
- Relationships between ideas (math and logic): formulas of analytic propositions (in the predicate that is contained in the subject and is necessarily true; if it were not, it would fall into contradiction).
- Knowledge of facts: it cannot have another justification in the last term than experience. Impressions as a criterion of truth in ideas.
Critique of Facts
A critique of the idea of cause: applying this criterion in its strict sense, our knowledge is limited to current impressions, memories of past impressions, but we cannot have knowledge of future events, and we do not have any impression of what will happen in the future. Now, in our lives, we permanently count on certain events that will happen in the future. Hume notes that all our certainty about the future is based on causal inference.
Causality and Necessary Connection
The idea of cause is thus the basis of our inferences about events of which we do not have an actual impression. Hume notes that this relation is usually conceived as a necessary connection between the cause and the effect. This connection is necessary to know with certainty that the effect will necessarily occur.
Blasts the Required Connection
A true idea comes from an impression, but we have never observed a necessary connection between both events. The only observable thing is that after one event, the second always happens, that between both events, a constant sequence is given, but there is no necessary connection between them. And as knowledge of future events can only be justified if there is a necessary connection between what we call cause and effect, we do not know if the water will get hot; we just suppose it will be so. Our assumptions and beliefs do not mean that we are not absolutely certain about these events: we all affirm with absolute certainty. According to Hume, this belief stems from the habit of having observed in the past that whenever the first event happens, the second one also happens.
World, God, and the Existence of the Self
Our certainty about unobservable events is not based on knowledge but on practical belief. Hume thinks this is enough to live. Causal inference is only acceptable between impressions. We can move from one impression to another but not from one impression to something we have never had experience of. Impressions of external reality to a reality that is beyond them and of which we do not have any impression or experience. The belief in the existence of a corporeal reality distinct from our impressions is therefore unjustifiable by appealing to the idea of cause.
Phenomenalism and Skepticism
Hume’s limits lead to phenomenalism and skepticism about human knowledge, which is an entanglement of impressions and ideas associated with each other. Firstly, regarding impressions considered in isolation, they are primitive elements for which it is not possible to find any foundation or explanation. Secondly, regarding perceptions associated with each other, we cannot find real connections between them but only their sequence or contiguity. There is no real basis for the connection of perceptions, no principle of unity that is different from them. This is the meaning of Hume’s phenomenalism, which concludes in a skeptical attitude (compare with Descartes).