Philosophy of the Enligthenment

* Book: Ernst Cassier. La philosophie des Lumieres.

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Summary

Based on the booknotes of Michel Bauwens, 2005:

Chapter 1

The 17th cy. was the century of systems: Descartes, Leibniz, Malebranche, Spinoza. It was a whole system of deduction, starting from first principles, to build a self-enclosing total explanation.

In the 18th cy., this form of reason, or 'esprit de systeme', is abandoned for an 'esprit systematique', which starts by examining the phenomena, and tries to develop the principles behind them. It is an analytical method, which decomposes, then recomposes, in order to understand. Whereas the 17th cy desired a mathematical physics, and therefore almost elevated math to a new metaphysics, the 18th cy wanted a purely descriptive and empirical reality, no matter if it could also be described by beautiful mathematical formulas. Reality comes first!

Reason is no longer the discovery of 'innate ideas', common to all mankind and the divine, but it becomes the path of analysis-synthesis, a 'discovery'. Cassirer clearly shows that reason has a history! The 18th cy started to see everything as a physical reality that could be analyzed: the sensations from nature, mental events, and society. Everything is considered to exist from fundamental building blocks, which have to be discovered, their relations if possible explained through mathematics. The aim of the use of Reason, is to bring unity to the diversity of phenomena.

Chapter 2

The next chapter discusses physical-mathematical reasoning and explains how this means a new form of Truth is invented, one that is outside of Revelation, located in nature, and much more trustworthy because expressable in mathematics. Newton, following Galileo-Kepler, had gone beyond particular findings to discover the 'basic law of the cosmos'. A novelty of the 18th cy is that individual entities are now seen as independent, that they can affirm their singularity vis a vis the universal (Leibniz's monad). The Newtonian revolution meant, and this is why he was venerated during the Enlightenment, that physical reality now had a sound foundation; and was matched by humanity's capacity to know these natural laws.

The Enlightenment, according to Cassirer, is a further working out and solving of the problems posed by the pioneers of the Renaissance. The 18th cy overturns Cartesian physics and the system philosophies which start from general principles. Reason moves from rationalism to empiricism. The intellect is now focused on the relationships between things and phenomena, and explicitly refuses to venture into the essence of things. Thus, Cassirer, refutes that mechanism and materialism were central tenets because this would already be a metaphysical affirmation. A key problem was the 'uniformity of nature', which made it necessary to develop scientific hypotheses, but were themselves not provable. Thus the move to the scepticism of Hume, who divorced certainty from metaphysics, and made it immanent, i.e. a component of human nature.

Any transcendence is therefore abandoned, as nature and knowledge have only immanent principles. Knowledge has therefore henceforth to be grounded in reality, through observation and experimentation, i.e. the approach has to be empirical, and the model for the sciences becomes the model for all knowledge, including morality.

The activism of the Enlightenment, very strong in Voltaire, consists in demolishing any theological hold on physics. Descartes had tried to reduce the natural world to geometry, but failed, so Newton abandoned it to focus on induction, experimentation, and analysis. Never start from abstract principles! And never anticipate experience. Thus knowledge is always provisional.

France had been thoroughly dominated by Descartes and Cartesian thinking; Germany had been subtly influenced by Leibniz, while England had been divided between the empiricists and the 'Cambridge Neoplatonists'. The great debate throughout Europe had been between the visions of Descartes and Newton however.

Using a 'genetic' and historical method to uncover the basis of our knowledge, Locke's contemporaries and successors were not 'intellectualists', as we may now think. On the contrary, they agreed that it was the passions who were primary, based on the pleasure/pain polarity, driven by survival instincts, and that therefore, higher logical operations could only be derivative. 17th cy. thought had already payed a lot of attention to the role of emotions and instincts, but saw them eventually as perturbations coming from the body, and therefore called for rational mastery. 18th cy thought however, saw them as the basis of a derivative rationality.

The 18th cy further eliminates any notion of substance, replacing it by causality. However, La Mettrie and Holbach espoused radically materialist, and even 'fatalist' positions, arguing that only necessity existed in nature, and that liberty was an illusion; and therefore, that atheism was an obligation. Against this, not only the religious forces reacted, but also other 18th cy thinkers, who wanted to preserve human creativity. Diderot, who changed his positions many times, introduces a dynamic element in the 18th cy thought: nature is too rich and moving to fix it in any static theory, thus we have no choice but to perpetually refine and adapt our descriptive theories.

Chapter 3: Theory of Knowledge

The 18th cy thought was self-critical: it was not just directed outward but to itself as well, motivated by positing clear epistemological principles to establish validity. 17th cy Cartesian rationalism has a metaphysical basis: we can know nature through our senses, only because we have corresponding ideas (numbers, extension, etc ..) which are a reflection of the divine inside us. But the 18th cy wants to establish knowledge on its own basis. From then on, it was held that knowledge can only come from the impression that it receives. The towering figure in the first half of that century was therefore John Locke. His contemporaries valued him more highly than Plato, and added that between Aristotle and him, no advances had been made. But whereas Locke still distinguished exterior sensation and interior reflection, his successors would unify this dualism.

Mental operations are not innate, but derive from sensations that originate from the body. Reducing mental life to primary emotions, Hume goes so far as to explain religion as innate because it is born from fear. A key issue was: is sense perception sufficient "to form our picture of the world, or does it need the cooperation of other faculties ? Is space a quality of the universe, or a feature of our perception ?

When the latter hypothesis became verified, it became clear that the different senses each have their own spaces, which are only coordinated through repeated habit. From there, it was an easy step to recognize the relativity of knowledge, another important tenet of Enlightenment thinking. It became clear that reality was not just objective, but a subjective-objective relation, dependent on our perception. Berkeley was the only 'idealist' of the 18th cy, going against the grain.

Chapter 4: Religion

The Renaissance had already given a new impulse to religion, by combatting its world-denying forms and stressing the material world was a manifestation of the divine. This religious humanism of the XVI-XVIIth cy, re-interpreted the dogmas of the Church (and was 'Pelagian' in spirit), but was combatted by the Reformation, even if the latter shared the engagement with the world. Thus the 17th cy was one of religious movements opposed to the spirit of the Renaissance, and opposed to the autonomy of Man. It was a century of religious war and dogmatism. The 18th cy would retake, conscious of historical evolution, the legacy of the Renaissance.

A key transition was Pascal, who defended Augustinian original sin, but using the form of awareness of the Enlightenment.

The key issue was the following: could philosophers explain evil in naturalistic and immanent terms ? Thus the great debates involving the doctrine of optimism (Leibniz) vs pessimism. Rousseau f.e. accepted the dire reality of man, but refused original sin. He was the first to distinguish natural man from cultural man, and to impute some of the evil to society, to the social order.

Generally, the Enlightenment was not against faith, but against superstition. Not the lack of knowledge is the problem, but a spirit full of prejudice. Thus they saw faith and science as going together, not as opposed to each other, but both equally distant from ignorance.