Rene Descartes and David Hume: Methods and Metaphysics

Posted on Dec 12, 2024 in Philosophy and ethics

Rene Descartes

The Cartesian Method

Descartes states that the method is “a certain set of rules, and easy, such that anyone observing them will never take something false as true, and without the cost of mental effort, but by increasing their knowledge step by step, reaches a true understanding of all the things that do not exceed their capacity.”

The method is to be applied logically to the operating mode of reason and is thus proposed here as we see Descartes‘ intuition and deduction as the only two ways of knowing and, therefore, as those elements that must be built into the method, offering its definition in Rule III: “I understand by intuition not the fluctuating belief in the testimony of the senses or the deceptive judgments of the imagination, but a concept of pure and attentive mind, so easy and distinct that there is no doubt about what we think; that is, a concept of pure and attentive mind which arises from the mere light of reason, and is more certain than deduction itself.”

Intuition is therefore the basic element of knowledge. Intuition necessarily establishes a direct relationship with the object, so the character of immediacy should be emphasized. Intuition is a kind of light or natural instinct that leads to simple natures: on average they immediately grasp simple concepts emanating from reason itself, without any possibility of doubt or error. It’s how we understand simple truths.

He says that intuition leads us inevitably to a deduction, which consists of a succession of intuitions, supported by memory.

The deduction “is a transaction by which we understand all the things that are a necessary consequence of others known to us with certainty.” Later, we distinguish intuition by saying that deduction envisages a movement and not the former, because deduction and intuition need not present evidence. In short, intuition gives us knowledge of the principles and deduction of distant consequences, which cannot be reached otherwise.

Rules of the Cartesian Method:

These rules of the method can be summarized in four principles: evidence, analysis, synthesis, and counting.

1. Rule of Evidence: Accept nothing as true that is not known with certainty to be so.
2. Rule of Analysis: Divide each difficulty to examine into as many parts as possible and as required to solve them better.
3. Rule of Synthesis: Conduct my thoughts in order, starting with the simplest objects and easiest to learn, to climb gradually, as by degrees, to the knowledge of the most complex, even assuming an order among them that naturally precede one another.
4. Rule of Enumeration: Conduct tallies so complete and reviews so general that one could be sure not to omit anything.

Conclusion: The truth does not depend on any external experience ourselves. True understanding is a design in mind. This is the method: a set of rules of bringing the mind to its own laws. Descartes’ error is trying to escape back to the most absolute, that is what the spirit has by itself and does not depend on any external factor.

Doubt as a Method

Descartes used doubt just to seek the truth. Doubting everything is only a methodological procedure to find an indubitable truth.

1. Distrust information from the senses. The senses are presented as the main source of our knowledge; however, I have often found that the senses deceive me. I consider, therefore, that by no means certain is the knowledge, and consider false all derived from the senses.
2. Inability to distinguish when we dream or when we are awake. However, it might seem exaggerated to doubt everything that I perceive through the senses, since it seems obvious that I’m here and things like that, but, says Descartes, that security in immediate sensitive data can also be questioned. The indistinguishability between sleep and wakefulness leads me to doubt, expanding the sensible to the intelligible, so that all my skills now seem to me highly uncertain, and do not serve to justify an absolute certainty.
3. Distrust of reason. He seems to have some knowledge of which can not reasonably doubt. However, Descartes raises the possibility that the same God who created me was able to create me so that when I judge that 2 + 2 = 4, I’m wrong. In fact, sometimes He allows me to be wrong, so it could allow that I am always mistaken, even when I judge of truth as “obvious” as mathematical truths. In that case, all my skills would be doubtful as the criterion, all should be considered false.
4. Scenario of an evil genius bent on confusing or misleading. However, since the former possibility may seem offensive to believers, Descartes raises another option: that there is an evil genius who is always interfering in my mental operations that do so consistently take the false for true, so I am always fooled. In this case, since I am unable to eliminate that possibility, because sometimes I really am cheating, I consider all my skills are suspect. Thus, the question also extends to all knowledge that does not seem to derive from experience. This hypothesis is to assume that maybe my understanding is such that it necessarily and always is wrong when it believes it has grasped the truth. But Descartes, as a rationalist, believes that man, his reason properly used, can get at the truth in all fields of knowledge.

Reality (Metaphysics)

First Truth: I Think, Therefore I Am

As we have seen, doubt has bracketed certainties even more common: Descartes now distrusts all. The question does not, despite its radicalism, bracket a first absolute certainty: I am. If I were not, I could not be deceived. Therefore, while thinking I’m wrong, it is undeniable that I am.

The very act of doubting comes with an indubitable truth: I think, therefore I am. This truth is taken by Descartes as the first principle of philosophy evident. It is a truth clearly and distinctly to be drawn from all the other truths.

For Descartes, thinking is all that happens within us: doubt, understand, affirm, deny… enjoy every thought, the obvious nature of the doubt. This implies a subjectivist stance: the evidence occurs only inside the subject. This evidence, “I think, therefore I am,” is not the result of a deduction; it is an intuition, that is immediately evident. It is an immutable principle, which no doubt is absolutely true. Descartes says “I think, therefore I am” is the intuition that I exist as a substance whose whole essence or nature is to think. This will start building the Cartesian philosophy from that first truism, and using a fundamental concept: the concept of substance.

Therefore, we have the criterion of certainty: it will be true all that is perceived with equal clarity and distinction.

David Hume

Knowledge

– The origin of knowledge and its classes: Empiricism sees experience as the source and the limit of our knowledge. This will involve the denial that there are “ideas” not coming from experience. For Hume, the experience is constituted by a series of impressions, whose cause is unknown and, strictly speaking, not to be identified with “the world” or with “things.”

Empiricism takes as a starting point of philosophical analysis of consciousness. Empiricists begin their research by analyzing the contents of consciousness.

– Impressions and ideas: Hume found two different types of content: impressions and ideas. The difference between the two is simply the intensity with which we perceive them, impressions being more intense mental contents and ideas less intense mental contents. The relationship between them is that ideas are derived from impressions; the impressions are original elements of knowledge.

• Impressions: immediate data of experience
• Ideas: copies weakened the impressions in the mind

Impressions can be of two types:

• Sensations: whose cause is unknown, and they are what we perceive through the senses.
• Reflections: those which are associated with the perception of an idea.

In addition, impressions can also be classified as simple or complex. A simple impression would be the perception of a color; a complex impression would be the perception of a city.

– The laws of the association of ideas: “It is clear that there is a principle of connection between the different thoughts or ideas of the mind and introduce us to others with some degree of order and regularity.” The ability to combine ideas seems limited. But little that we are held to reflect on how does this combination of ideas we can see how, “even in our wildest imaginings,” that association is always following certain laws, that of resemblance, contiguity in time or in space, and cause or effect.

– Relations of ideas and matters of fact: Hume raises the question of what forms of knowledge are possible. He said that all objects of reason can be divided into two groups: relations of ideas and matters of fact.

a) Relations of ideas: The objects of reason in the former group are “the science of geometry, in short, every affirmation which is intuitive or demonstrative.” The characteristics of these objects can be known is that regardless of what exists “elsewhere in the universe.” They depend only on the activity of reason.

b) Matters of fact: Matters of fact cannot be investigated in the same way, as the opposite of a fact is, in principle, always possible. If we are convinced that an event has to occur in a certain way, it is because experience has made us always associate it with another event that precedes its cause or effect.

We can therefore speak of two types of knowledge in Hume: knowledge of relations of ideas and knowledge of facts.

Reality

– The criticism of the principle of causality:

But what does the idea of causation contain exactly? According to Hume, the causal relationship has been traditionally conceived as a “necessary connection” between cause and effect, so that we know the cause, reason can tell the effect is to follow, and vice versa. What happens if we apply the criterion of truth established by Hume to determine if an idea is true or not? An idea will be true if there is an impression that corresponds. Is there any impression that corresponds to the idea of “necessary connection,” and therefore its use is legitimate, or is it a false idea that does not correspond to any impressions? If you look at any issue of fact, for example, the collision of two billiard balls, says Hume, we observed the movement of the first ball and its impact (cause) on the second, which is set in motion (effect). In both cases, both the cause and the effect are, for them, an impression; if true, those ideas. We believe that if the first ball hits the second, it will move to assume a “necessary connection” between cause and effect: But is there an impression that corresponds to this idea of “necessary connection”? No, says Hume. All I see is the sequence from the first ball movement and the movement of the second; the only thing we sense is the idea of succession, but nowhere appears an impression that corresponds to the idea of “necessary connection.” Thus, we must conclude that the idea that there is a “necessary connection” between cause and effect is a misconception.

How does, then the idea of substance, on which many philosophers have agreed? The idea of substance is produced by the imagination; it is merely a “collection” of simple ideas united by the imagination in a term that allows us to remember that collection of simple ideas, a collection of qualities that are related by contiguity and causation. For Hume, the idea of substance is a misconception, whether conceived as material as if it is like a spiritual thing, since it is not for any impression. A critique of the idea of substance is added to the study of the alleged abstract ideas or concepts. Can we accept the existence of ideas, abstract concepts, general, universal? Or, conversely, are all our thoughts private? Talking about abstract concepts is to accept the possibility of a universal way to represent reality and, by extension, the essence, the substance of reality. But do we really have a single abstract concept, a single abstract idea? Is it possible to conceive of a triangle that is not isosceles, scalene, or equilateral, but that is all and each of the triangles can exist? No, says Hume. When I speak of the abstract concept of the triangle, in my mind is the image, the representation of a particular triangle, particular to which I add the attribute, fiction, that represents any triangle, just as if I conceive the idea of “dog,” I represent a particular dog, to which I add the attribute, fiction, to represent all the dogs. All ideas are therefore private. What we call concepts or abstract ideas are the result of an inductive generalization from experience, which end up giving the same name to all objects that match some resemblance or similarity.