Rationalism

René Descartes broke with scholastic tradition, starting modern philosophy in general and rationalism in particular.

Rationalism is a philosophical current that emphasizes the role of reason in the acquisition of knowledge. It contrasts with empiricism, which highlights the role of experience, especially the sense of perception.

Rationalism developed in continental Europe during the 17th and 18th centuries. Traditionally, it is considered to begin with René Descartes and his expression "I think, therefore I am". Descartes said that geometry represented the ideal of all sciences and also of philosophy. Descartes claimed that certain universal truths could only be discovered through reason, totally contrary to the idea that the empiricist movement was driving. From those truths it is possible to deduce the rest of the contents of philosophy and science. He claimed that these self-evident truths were innate, not derived from experience. This type of rationalism was developed by other European philosophers, such as the Dutchman Baruch Spinoza and the German thinker and mathematician Gottfried Wilhelm Leibniz. It was opposed by British empiricists such as John Locke and David Hume, who believed that all ideas come from the senses.

Rationalism maintains that the source of knowledge is the reason given by God and rejects the idea of the senses, since they can deceive us; defends the exact sciences, specifically mathematics. Descartes wanted to return philosophy to scientific knowledge, therefore, give it a scientific method, so it was based on mathematics, which was considered a safe science, for this reason it was given the task of describing the principle of mathematization, in his book Method Discourse, to carry out a philosophical investigation. The method consists of four rules:

1. Evidence: It is only true that which gives no doubt to thought.
2. Analysis: reduce the complex to simpler parts to understand it correctly.
3. Deduction: To allow the rational deductive operation the weight of the research, to find the complex truths from the deduction of the simple.
4. Check: Check if you discovered it from reason was obtained through these above-mentioned rules.

Nasistodological rationalism has been applied to other fields of philosophical inquiry. Rationalism in ethics is the claim that certain primary moral ideas are innate in the human species and that such moral principles are self-evident to the rational faculty. Rationalism in the philosophy of religion asserts that the fundamental principles of religion are innate or self-evident and that revelation is not necessary, as in deism. Since the late 19th century century, rationalism has played an anti-religious role in theology.

The term rationalism has a very broad meaning: in general, we call rationalist any philosophical position that prioritizes the use of reason over other instances such as faith, authority, the irrational, the empirical experience, etc. Anyone who believes that the foundation, the supreme principle, is reason is a rationalist. Along with this, it is possible to be a rationalist in relation to one genre of questions and not to be so in relation to another. The term rationalism is commonly used in the history of philosophy to designate a certain way of founding knowledge: it is possible to think that knowledge rests on reason, values reason more than the senses, we can call rationalists Parmenides, Plato and Descartes; and we can say that Aristotle, Saint Thomas and, of course, Hume, tend towards empiricism, given the value they gave to sensible experience or perception.

Influential rationalists included Christian Wolff, René Descartes, Baruch Spinoza, and Gottfried Leibniz.

Historical context

In the early 17th century century, most philosophy was dominated by scholasticism, written by theologians and based in the writings of Plato, Aristotle and from church writings. Descartes argued that many prevailing scholastic metaphysical doctrines were meaningless or false. In short, he proposed starting philosophy from scratch. In his most important work, Metaphysical Meditations, he attempts just this, in six short essays. He tries to get rid of all his beliefs to determine what he knows for sure. He finds that he can doubt almost everything: the reality of physical objects, God, memories of him, history, science, even mathematics, but he cannot doubt that he is, in fact, doubting. He knows what he is thinking about, even if what he thinks about content is false, he knows that something must exist to be thinking about it. From this base he rebuilds his knowledge. He finds that some of the ideas he has could not have originated from him alone, but only from God; thus, he tries to prove that God exists. Then he tries to prove that God would not allow him to be systematically deceived about everything; in essence, he vindicates the ordinary methods of science and reasoning, as fallible, but not false.

Rationalism is a European philosophical current that was later subdivided by historians into two antagonistic blocks: rationalism and empiricism. It covers the entire 17th century and is a long and intense metaphysical epilogue to the great advances in Renaissance science. In it, philosophy adopts the mathematical paradigm of geometry and the experimental paradigm of physics, opposing both Pyrrhonic skepticism and scholastic formalism. Its main features are:

• Trust in the power of reason.
• Postulation of innate ideas.
• Use of the logical-mathematic method to explain empirical reasoning and confirm them when possible.
• It's a total truth.
• They treat abstract notions as a duty, a law and justice.
• The rationalists believe in the principle of [Idealism] which refers to everything that exists in the mind of God and the creation of the world from ideas and numbers.

Rationalism vs. empiricism

Rationalism and empiricism are totally opposite, below is a table with some differences between these two:

Notable rationalists

• René Descartes: Founder of rationalism (which continued Antoine Arnauld, Malebranche, Spinoza and Leibniz)
• Blaise Pascal: Founder of modern existentialism (which will continue Jacobi and Kierkegaard)
• Spinoza: Founder of modern pantheism (to continue d'Holbach, Schelling and Hegel)
• Malebranche: Founder of spiritualist monism (which will continue Berkeley and Bergson)
• Pierre Bayle: Founder of deism (to continue Voltaire, Rousseau and Kant)
• Leibniz: Precursor of German idealism and remote founder of analytical philosophy (which will continue respectively Kant, Fichte, Schelling and Hegel, on the one hand; and Frege, Russell and Wittgenstein on the other)