Rationalism vs. Empiricism: 17th-18th Century Thought
The Modern Age (17th – 18th Centuries)
The 17th century saw the Renaissance, and the 18th century, the Enlightenment. What happened in the 15th to 16th centuries changed the way people thought, due to a scientific revolution. This involved a shift from Aristotelian physics, which had prevailed since the 4th century BC, to the emergence of modern physics.
The transition from a geocentric to a heliocentric model was difficult for the church and the scientific community to accept. Why, if God created us, are we not the center of the universe? The acceptance of heliocentrism was challenging because it meant that man was no longer the center of the universe.
Once this was accepted, the path to the mathematization of the universe opened, suggesting that the universe could only be explained by mathematics and that it was infinite.
The hypothetical-deductive method, based on induction and deduction (experience and reason), was also adopted, particularly in light of Galileo’s work.
Steps of the New Scientific Method:
- Observation of a phenomenon.
- Scenario (based on analysis performed).
- Theory (abstract).
- Verification, leading to a scientific law.
Due to all these changes, the Modern Age is characterized by the secularization of thought. Human knowledge became separated from faith, with reason and the senses becoming the new sources of knowledge.
The 17th century saw the rise of rationalism and empiricism.
Rationalism posits that the source of knowledge is reason, the object of knowledge is innate ideas, and that the senses deceive us and should not be relied upon.
For rationalism, consciousness is the source and is full of content.
Rationalism | Empiricism | |
SOURCE OF KNOWLEDGE | Reason | Senses |
OBJECTS OF KNOWLEDGE | Innate ideas | Acquired ideas |
ORIGIN OF KNOWLEDGE | Consciousness (loaded with content) | Consciousness (empty of contents) |
Descartes (17th Century)
Descartes was a French philosopher who advocated for rationalism.
The Cartesian method consists of a set of simple rules that, if followed, prevent one from confusing truth and falsehood, gradually leading to knowledge of everything within reach.
The Four Rules of the Cartesian Method:
- Subjecting knowledge to doubt.
- Hypothesis.
- Synthesis.
- Verification.
Only the first rule differs from the hypothetical-deductive scientific method.
Descartes subjected all his knowledge to doubt to determine its truth and correctness. This is his major difference from Galileo.
Types of Doubt:
- Senses.
- Confusion between sleep and wakefulness.
- Mathematical propositions.
Our senses often fail us, so they must be subjected to doubt.
The confusion between sleep and wakefulness is a problem. Descartes questioned whether genuine reality is the waking state or the dream state, as we have no certainty of it.
Descartes asked, “Is there something that is impossible to doubt?” What we cannot doubt is the fact that I doubt; therefore, I think.
“I think, therefore I am.”
- Thinking substance.
- Corporeal or extended substance.
- Infinite substance.
The thinking substance produces ideas. Ideas can be acts of thought or representations of designed objects.
As acts of thought, all ideas are equal. However, as representations of designed objects, they are divided into three types:
- Adventitious ideas: Represent objects received through the senses (ideas that come from outside).
- Factitious ideas: Represent ideas created by the subject, based on others they already have.
- Innate ideas: Ideas that we are born with, such as the idea of infinity.
The idea of infinity is represented by God, but not the God conveyed by the church. Instead, it is an external and perfect God.
Descartes argues that there can be no idea without an object, and that object is God, his trademark, like a painter signing their work.
The answer is the corporeal or extended substance because God, or the infinite, guarantees your life. Your senses may deceive you, but the infinite does not.
Once the three substances are shown, how do they connect? Substance is defined as that which does not need anything or anyone to exist, which is the infinite, or God.
This also applies to thought and extension. Descartes uses Cartesian dualism because thought does not need the body to exist, nor does the body need thought.
But how do they communicate? This remains unknown, leaving the problem of “THE REPORTING OF SUBSTANCE.”
How many people have awakened from a coma, unable to move but still able to listen and think? What is the relationship between body and mind?
Empiricists have shown that we cannot have experience of these three substances because they are beyond us. This leads to atheism, as there is no sensible experience of God or ourselves. We only have the deposits of our senses, which vary. So, should we believe that we have experience of ourselves?
The body, or res extensa, is like a machine with no hidden forces that encourage it, leading to ideas contrary to rationalism.