The Enlightenment of the 18th Century

The Enlightenment Project

When? 1687 (Sir Isaac Newton's Principia Mathematica)

Who? The intellectual elite of Europe (a tiny, but highly influential group)


Natural Laws 

  • The Universe is governed by natural laws. It is a mechanism with patterns built into it. 

Science and Reason

  • These natural laws are discoverable through the use of reason, specifically through the use of the scientific method: deductive and inductive reasoning.

Applied to Human Affairs


  • The same paradigm applies to human nature and to human society. There are proper political systems and proper economic systems.


  • We are rational beings. We are born with an innate rational ability which, if properly trained, enables us to develop a moral sense: an understanding of correct and incorrect behavior.

Therefore Progress is possible

  •  If we fit our political and economic systems to the appropriate natural laws and if we fit our legal system to our moral values, then progress is possible towards a better world. Education is the key to achieving progress.

A Universal Civilization

  • We are all alike, no matter what our cultural, religious or racial background might be. There is a path which will lead us to a better place: emancipation, affluence, and a civil society.


II. Enlightenment Goodies

Science and Technology

  • Modern technological advancement is the result of the Enlightenment belief that progress is possible by taking advantage of our understanding of the laws of nature.

Our Political Values

Liberal political values are based on the enlightenment search for a perfect political system:

  • one which protects our natural rights,
  • guarantees equality before the law,
  • protects the freedom of speech, press and religion,
  • provides checks and balances between separate branches of government
  • separates church and state.

Our Economic Values

  • Our economic systems should follow a rational pattern governed by laws that have been demonstrated by history. Both capitalism and socialism are children of the enlightenment because both rely on rational approaches to the regulation of society.


III. The Enlightenment and Religion

Anti- Christian

  • The philosophes held that Christianity was harmful. Irrational beliefs held the world back from progress: superstition, myth, unverifiable truths.

But also parallels

  • You could call the philosophes' belief in progress a secular religion: the philosophes were engaged in a mission to improve the world which imitated the missions of Judaism, Christianity and Islam. Although Voltaire, D'Holbach and Hume were agnostics or even atheists, their belief in progress had been shaped by Christianity. In its essence the conception of natural law requires the will to believe in a primary cause.


  • Many philosophes believed that religion served a useful function as a controlling ideology for the masses which taught obedience through the fear of God.

Human Nature

  • Many philosophes believed that human nature had been so warped by environment that it had been irremediably corrupted. Therefore, religion became a necessary evil.
  • Voltaire said, "I want my lawyers, my tailors, and even my wife to believe in God." He also said, "If God does not exist, it would be necessary to invent him."


An Alternative: Deism

Deism Defined:

  • Belief in god based entirely on reason, without any reference to faith, revelation, or institutional religion. 
  • Many philosophes tried to resolve the conflict between science and religion by inventing a 'rational religion'. Deists believed that God had created the universe and then retired. The world works according to the laws he created. The fact that the natural world is so well designed is evidence that God must exist.

The Theodicy Issue

Theodicy Defined:


  • "God's justice": an attempt to explain or defend the perfect benevolence of god despite the apparent presence of evil in the world.
  • Deists had to resolve a major philosophical dilemma to align their belief in God with reason: If God is good and omnipotent, then how can evil arise?

In the Deist's Universe

  • The solution to this dilemma was the doctrine of optimistic determinism which argues that the universe is a wonderful mechanism governed by laws which work to the benefit of human beings... but which can also create natural disasters... which somehow must exist for the benefit of mankind, if not the benefit of individual humans. (The Argument According to Design: Leibniz's Theodicy)

On a Human Scale

  • Furthermore, contrary to the Christian belief in original sin, humans are born good in that we possess reason and the ability to develop a moral sense.


IV. The Enlightenment and Cultural Pluralism

  • The philosophes asserted that all people are governed by the same natural laws and are bound for the same universal future. They were cosmopolitan, members of an international community which did not acknowledge national, cultural or religious identity. Furthermore, the philosophes believed that all humans possess certain natural rights regardless of their religion, culture or nationality.
  • Other thinkers will argue that cultural differences create people with different values that should be respected, not homogenized into one universal system (and that is not necessarily wrong.)

V. The Enlightenment and the Heart

  • The philosophes held that human emotion is bad. Irrational passions are the source of most of society's problems. Is reason always right?

VI. The Enlightenment Against Itself

  • There are logical contradictions in some of the assumptions of the philosophes:
    • Are the philosophes right to assume that the universe was created according to rational laws?
    • Are they right to assume that all people possess natural rights?
    •  If these premises are not provable, shouldn't we doubt them?