Death of Socrates
The Death of Socrates, by Jacques-Louis David (1787)

In the 17th and 18th centuries, an intellectual shift moved the scientific and social tectonic plates of Europe. This Enlightenment, drawing from the legacies of the Protestant Reformation, which challenged medieval religious thought; the Renaissance, which challenged medieval scientific and social thought; and the Scientific Revolution, which challenged medieval and traditional Judeo-Christian beliefs about science and nature, launched as a response to medieval superstition and to the question of man’s place in the universe.

An emphasis on reason characterized the Enlightenment, which made philosophy a matter of individual interpretation. Through reason man could find release from the old and improve his condition. A criticism of absolute monarchies led to championing of various ideals that would influence emerging nations like America, including the rule of law, freedom of speech and religion, private property, and impartial judiciary.

Francis Bacon (1561-1626)

Sir Francis Bacon
Francis Bacon (Artist unknown)

“Man, being the servant and interpreter of Nature, can do and understand so much and so much only as he has observed in fact or in thought of the course of nature: beyond this he neither knows anything nor can do anything.” – Francis Bacon, from Novum Organum

While more a thinker of the Scientific Revolution than the Enlightenment, Bacon deserves a mention because his Baconian method of science greatly shaped the Enlightenment belief in the ability of human intellect to improve society.

In his major political essays, Bacon presented natural science as an instrument to strengthen a nation. Unlike Plato, who proposed in Republic that philosophers should lead society, in his utopian vision New Atlantis Bacon presented the scientist as the ideal leader, for such a figure possessed the intellectual skills to ward off the Idols (discussed below) that hindered scientific, and thus social, progress. Knowledge, he argued, is “a rich storehouse, for the glory of the Creator and the relief of man’s estate” (Advancement of Learning, introduction, par. 6).

Bacon's New Atlantis
Bacon’s New Atlantis (Artist unknown)

According to Bacon in his most famous work, Novum Organum, “science” to that point had relied on easily confused and overhastily abstracted syllogisms, easily accepted generalizations, and little observation (Book I.XIV). This type of exploration he termed Anticipations of Nature, and remarked that men made no great scientific progress through it.

Rather than Anticipations of Nature, Bacon promoted Interpretations of Nature, which involved analysis of nature based on much and widely-dispersed data. Observation, experimentation, and induction was key to finding any real truths. This method required the rejection of four Idols, false notions that blocked the possibility for good empirical investigation:

  • Idols of the Tribe (belief that one’s individual perceptions are universal)
  • Idols of the Cave (perceptions affected by personality and experience)
  • Idols Market Place (confusions of meaning caused by the errancy of language)
  • Idols of Theater (dogma)

Rene Descartes (1596-1650)

Rene Descartes
Portrait of Rene Descartes, after Frans Hals (c. 1649-1700)

Rene Descartes echoed Bacon’s interest in experimental science, with the exception that while Bacon believed that knowledge began in sense experience (empiricism), Descartes believed that it began in the human mind (rationalism). He lived in the context of post-Protestant Reformation and -Enlightenment Europe, when religious and social divisions led to confusions about authority and new tensions arose between the church and science.

Descartes yearned for knowledge, and by the instruction of teacher he sought it in books, only to find that they left him, by their diversity of thought, “involved with so many doubts and errors” (Discourse on Method, pt. 1, par. 6). Thereby he abandoned his studied to seek knowledge through nature and his own devices – that is, by reason alone. Ultimately, he focused his attention on study of self.

Descartes began this study by relinquishing all preconceived notions and unsupported childhood principles. In his travels he realized how greatly custom more than certain knowledge shaped opinion, and concluded that he could not accept as true the opinion which the majority held. From this perspective, he rejected as false whatever smacked of the least doubt, including perception of the senses, previously accepted reasoning, and thought.

Image from kissPNG

He left only what was self-evident – statements with essences similar to mathematical axioms. What remained: the incontrovertible truth and first principle of modern philosophy, “I think, therefore I am [cogito ergo sum].” Awareness of himself doubting affirmed that he existed.

From this breakthrough, Cartesian dualism emerged, which acknowledged the existence of a soul and a body (or mind and matter) and their distinction. Mind and matter interacted, but destruction of the body did not affect the mind. Where Descartes could reject that his body existed, given his skepticism toward sense experience, he could not reject that his mind existed. Therefore, they must exist on separate planes.


In the next Enlightenment post, I delve into the main philosophical ideas of John Locke, David Hume, and Immanuel Kant.