The Impact of the Scientific Revolution

Of all the changes that swept over Europe in the seventeenth and eighteenth centuries, the most widely influential was an epistemological transformation that we call the "scientific revolution." In the popular mind, we associate this revolution with natural science and technological change, but the scientific revolution was, in reality, a series of changes in the structure of European thought itself: systematic doubt, empirical and sensory verification, the abstraction of human knowledge into separate sciences, and the view that the world functions like a machine. These changes greatly changed the human experience of every other aspect of life, from individual life to the life of the group. This modification in world view can also be charted in painting, sculpture and architecture; you can see that people of the seventeenth and eighteenth centuries are looking at the world very differently.

The scientific revolution did not happen all at once, nor did it begin at any set date. Realistically speaking, the scientific revolution that we associate with Galileo, Francis Bacon, and Isaac Newton, began much earlier. You can push the date back to the work of Nicolas Copernicus at the beginning of the sixteenth century, or Leonardo da Vinci in the middle of the fifteenth. Even then, you haven't gone back far enough and you haven't included all the factors that contributed to the set of epistemological transformations that we call the scientific revolution.

Somewhere along the line, though, the astrologers and astronomers of the Islamic world decided that the Ptolemaic universe was, in fact, an accurate physical description of the motion of the universe. When Arabic science entered the European world in the twelfth and thirteenth centuries, so did the Ptolemaic world view. This view would go largely unchallenged for hundreds of years while the universe squeaked and wobbled in its eccentrics and epicycles.

Arabic numerals: We need to step back and briefly discuss one other innovation of the Middle Ages: the adoption of Arabic numerals. For Arabic numerals made the Copernican revolution possible in a way that can't be overstressed. Before the adoption of Arabic science in the twelfth and thirteenth centuries, Europeans used the Roman numeral system. This is a subtractive number system: numbers are indicated by letters and the transition to higher letters is first preceded by subtraction:

I - II - III - IV - V

While people were fairly proficient at working with these numerals, calculation was not exactly a blazing fast process. Try multiplying MDMCXLVII by CCCLXXIII without converting them to Arabic numerals and see how fast you can do it.

The immense advantage of a place system (only the Mayans and the Hindus also developed place systems) is that you can do calculations extremely rapidly. When this system was introduced into Europe, learned people began to calculate like mad. Books upon books piled up filled with calculations from the hands of monks and students and university teachers. Books of astronomical calculations especially began to pile up: this was the beginning of mathematical astronomy. As astronomical observations and calculations piled up, the problems with the Ptolemaic universe also piled up. More than anything else, it was this pile of mathematical calculations that pushed Copernicus to radically revise the Ptolemaic universe.

Nicolas Copernicus: Copernicus (1473-1543) was the first major astronomer to challenge the Ptolemaic universe. Let's keep in mind, though, that Ptolemy had his critics starting with Ptolemy himself. The Ptolemaic universe was, after all, a nonsensical affair; when King Alfonso of Spain was introduced to the system in the thirteenth century, he said, "If God had made the universe thus, he should have asked me for advice first." The result of this criticism was not one, but hundreds of versions of the Ptolemaic universe. Copernicus, in the year of his death, published On the Revolutions of the Heavenly Spheres. This book did not revise Ptolemy's system, as all previous criticisms had, but rather challenged the fundamental assumption of the Ptolemaic universe: that the earth was the center point of the revolution of the heavens. In many ways, Copernicus attempted to solve the problem of precession by coming up with the simplest possible explanation. By simply moving the sun to the center of the universe, almost all the problems with planetary precession disappeared (almost all). Copernicus was also a mystical philosopher; he believed that the sun not only symbolized but also contained God; putting the sun at the center of the universe was more than a mathematical solution, it also better explained the spiritual structure of the universe. The Copernican universe, however, was still nothing like our own. It was still a small and intimate place; moving the orbits of the stars out too far meant that they'd travel at impossible speeds. Copernicus also kept the Ptolemaic epicycles and argued that the planets moved in circular orbits. His system, though, was a far more accurate predictor of planetary motion than any that had been previously put forth. That, argued Copernicus, was more than enough to justify its adoption.

The Cartesian model Rene Descartes (1596-1650) had initiated a new mode of deduction. I n his Discourse on Method, (1627) he rejected every idea that could be doubted. He concluded that he could be certain of nothing except the facts he was thinking and that he must therefore exist. Descartes presents three main arguments to prove his thesis that the essence of a person is an immaterial thinking substance: Firstly, the famous "Cogito, ergo sum" "I am... only a thing that thinks." He says, not that our essence is only thinking, but rather that all we know of our essence is that at least part of it certainly is thinking.

The second of the three arguments requires a prior proof of the existence of a good and all-powerful God. Descartes launches into this argument:  God is good;  So, God does not deceive.  Everything that is clearly and distinctly perceived may be created by God to accord exactly with my understanding.  I have a clear and distinct idea of myself as a thinking, non-extended thing.  I have a clear and distinct idea of my body as a non-thinking, extended thing.  Therefore, I am distinct from my body. Sum res Cogitans.

He ultimately conceived of a unified and orderly universe, which operated as a perfect mechanism. In the Cartesian Universe supernatural processes are impossible, everything could be explained rationally, preferably in mathematical terms.

Tycho Brahe: The man who most greatly influenced the adoption of the Ptolemaic system was Tycho Brahe (1546-1601), who was one of those fanatics doing all those mathematical calculations of the motion of the universe. Tables and tables and tables of calculations. For a man with a boring profession, however, he led a singularly interesting life: temperamental, he had lost his nose to syphilis, or, rather, to the cure for syphilis; he was a raucous heavy drinker and he died a particularly just death for a heavy drinker. At a dinner with a prince, he drank a bit too much, and, since you were not allowed to leave the table until the person outranking you left the table, he waited out his full bladder until it burst and sent him to the heavens he had so lovingly observed and calculated.

Brahe opposed the Copernican universe and vehemently argued that the earth was the center of the universe. In order to prove this, however, he cataloged a superhuman number of astronomical observations and calculations. These tables of calculations made up the best astronomical observations in any culture at any time up to that point and would become the basis for proving the Copernican system to be a more accurate model of the universe.

Johannes Kepler: Like Copernicus, Kepler (1571-1630) believed that the sun represented the spiritual essence and presence of God and should be placed at the center of the universe. He discovered Brahe's observations and calculations and set about using them to develop a new, sun-centered universe. He rejected two major aspects of the Copernican universe: epicycles and circular orbits. In the Keplerian universe, the planets orbited around the sun and remained in their orbital paths; these paths, however, were elliptical rather than circular. This was the big prize: by revising Copernicus's model through the use of Brahe's calculations, he produced a mathematical model of the universe that perfectly predicted planetary motions and accounted for every instance of planetary precession. This model he published in the book New Astronomy in 1609, and it instantly created a sensation. It would also inspire an Italian astronomer, Galileo Galilei, to fit his new observations into this Keplerian universe. Even though the model was perfect in terms of its predictive power, it still had a number of problems. It still didn't explain why the earth didn't move out from under us when we jumped in the air. Also: why would the planets move elliptically? Circular orbits made sense, but elliptical orbits? Both of these questions would be answered by Newtonian physics a few decades later.

Galileo Galilei: Galileo (1564-1642) combined the two roles of observer and theorist and, more than anyone else, provided the empirical discoveries that cinched the Copernican-Keplerian universe. First, in 1609, he eagerly read Kepler's New Astronomy and bought into it completely. That same year he bought a curious new Dutch invention, the telescope. While the telescope had been around for a few years, he was the first to use it to systematically look at the heavens. What he saw amazed even him.

The first thing he saw was mountains on the moon. Until this time, the moon was regarded as more or less gaseous; the presence of mountains meant that the moon was terrestrial, just like earth. If it had mountains, it could also have plants and people. The second thing he saw were planets orbiting around the planet of Jupiter. Five, to be exact. This was the big banana. For if the planet of Jupiter was an independent orbital system orbiting around a larger system, that meant that the sun could also be an independent orbital system orbiting around a larger system. The universe, which until Galileo's time was a small and homey place, suddenly expanded infinitely outwards and became a vast and incomprehensible place.

Galileo announced his findings in The Starry Messenger, which he published in 1610, one year after the publication of Kepler's New Astronomy. The Starry Messenger was really only a pamphlet, and Galileo would not write a full exposition of his observations and his model for a much larger universe until his Dialogues on the Two Chief Systems of the World. It was this book that inspired the Roman Catholic Church to closely examine his observations and models and compare them to church doctrine and the texts of the Old and New Testament. The Church concluded that his ideas were at variance with both doctrine and Scriptures and demanded, on pain of death, that he recant his views.

The one part of Galileo's system that most greatly influenced all subsequent European inquiry into the nature of the universe was his insistence that the universe operated according to mathematical principles. The circle, you might say, had been completed. The Ptolemaic universe was a mathematical model designed to assist predictions but was not designed to be a physical description of the universe. Both the Copernican and Keplerian systems were primarily proposed as mathematical rather than physical models. Galileo insisted that the two were coterminous, that all physical description of the universe would of necessity be a mathematical description. His revolutionary argument was this: if a physical model did not fit the mathematical properties of that phenomenon, the physical model was wrong. This would become the basis of a profound shift in European knowledge: classical mechanics.

Francis Bacon: The grounds for a mechanical universe, that is, a universe that operated like a machine, was laid down by Galileo's insistence that the universe operated by predictable mathematical laws and models. In addition, Francis Bacon (1561-1626), added a key element to the genesis of the mechanical universe in his attacks on traditional knowledge. Bacon wasn't a scientist in our sense of the word, but he did take great joy in telling everybody why they were wrong. In particular, he argued that all the old systems of understanding should be abandoned: he called them idols. He believed that knowledge shouldn't be derived from books, but from experience itself. Europeans should move beyond their classics and observe all natural and human phenomena afresh. He proposed the Aristotelian model of induction and empiricism as the best model of human knowledge; in inductive thinking, one begins by observing the variety of phenomena and derives general principles to explain those observations. (In deductive thinking, one starts with general principles and uses these principles to account for the variety of phenomena). This model of systematic empirical induction was the piece that completed the puzzle in the European world view and made the scientific revolution possible.

Isaac Newton: The mechanical universe in all its glory would emerge from the work of Isaac Newton (1642-1727) in his compendious The Mathematical Principles of Natural Philosophy (1687), which is primarily known by the first two words of its Latin title: Principia Mathematica. The fundamental arguments of the book were the following:  The universe could be explained completely through the use of mathematics; mathematical models of the universe were accurate physical descriptions of the universe.  The universe operated in a completely rational and predictable way following the mathematics used to describe the universe; the universe, then, was mechanistic.  One need not appeal to revealed religion or theology to explain any aspect of the physical phenomena of the universe.  All the planets and other objects in the universe moved according to a physical attraction between them, which is called gravity; this mutual attraction explained the orderly and mechanistic motions of the universe.

Newton was not alone in developing his views; he built heavily on those who came before him. He used pieces of other’s work, creating a far greater result than the individuals before him created separately. He was the “Great Synthesizer.”

Newton's mechanistic view of the universe is an idea that derives from Greek atomism, but Newton's mechanistic universe would become the dominant model in European thought for the next several centuries. According to Newton, the universe was like a massive clock built by a creating god and set into motion. Actually, even though Newton was a devout Christian, this argument has a philosophical basis. For Newton based his entire view of the universe on the concept of inertia: every object remains at rest until moved by another object; every object in motion stays in motion until redirected or stopped by another object. (This latter principle explains why we can jump in the air without the earth moving out from under us). According to the concept of inertia, no object has the ability to move or stop itself. The universe, then, becomes a vast billiard ball table, in which everything moves because something else has just knocked into it or caused it to move.

But this leads to a serious philosophical problem: who moved the first object? How did the universe get going if no object can move itself? The Greek atomists, who believed that the universe consisted of atoms (in Greek the word atoma means "indivisibles") that create all phenomena by colliding into and combining with each other, explained this with the concept of "swerve": somewhere at the beginning of time, one atom swerved all by itself and knocked into another and hence the universe came into being. Aristotle, on the other hand, who also based his thought more or less on a mechanistic view of the universe, solved the problem by positing an "Unmoved Mover": somewhere at the beginning of time, an "Unmoved Mover" (which he calls God), was able to set things in motion without having to be moved itself. This idea was appropriated in the middle Ages by the Scholastics, who, like Aristotle, believed the universe functioned in a rational and mechanistic way and was set in motion and ruled over by a rational and unmoving mover, God. Newton adopts this idea whole-cloth: although the universe is a vast machine of objects moving and colliding into each other and functioning by its own laws, it still requires some original thing that set it all in motion in the first place. That thing, for Newton, was God.

But God did not interfere with the day to day workings of the universe (although Newton never denied that God couldn't, just that God didn't become involved). If the universe was a vast machine of interacting objects, which meant that it could be understood as a machine. Human reason and the simple observation of phenomena were sufficient to explain the universe; one need not drag religion or God into the explanation. If physical phenomena were mechanistic, that means that physical phenomena can be manipulated, that is, engineered. This mechanistic view of the universe, called classical mechanics, focuses entirely on the concept of motion, that is, at the base of Newton's thought is an attempt to explain why the universe moves. This is what physics is all about: why things change.

Newton's mechanistic view of the universe would soon be applied to other phenomena as well. If the universe was a machine and could be understood rationally, then so perhaps could economics, history, politics, and ethics (human character). It also followed that if economics, history, politics, and ethics were mechanical, they could be explained without recourse to religion or God and they could be manipulated as if they were machines, that is, they could be improved, engineered, and made to run better. As the Enlightenment developed, classical mechanics would give rise to a larger phenomenon, Deism, which is founded on the idea that all phenomena are fundamentally rational and mechanistic and can be explained in non-religious terms. All of modern Western knowledge and the majority of your experience is ultimately derived from this principle. Newton's separation of the mechanical universe from religious explanation and the Enlightenment concept of deism went further than this, however. If the universe was created by God and the universe was a rational place, which meant that God was rational. If one understood the workings of the universe, one understood the workings of the mind of God. So the separation of physical explanation from religious explanation was not as tightly enforced as it seems at first glance. The great innovation of this view for Western religion would be the Enlightenment insistence that religion itself be rational.

All the pieces were now in place, fused there by Newton's elaborate concept of a mechanical universe. Eighteenth century science saw an explosion of empirical knowledge about the physical world. A virtual flood of empirical observations and calculations inspired not only an increase in knowledge, but a massive effort to systematize that knowledge as Newton had done. The scientific revolution of the eighteenth century is, above everything else, characterized by fanatical conversion of knowledge into rational systems.

Newton’s revolution paved the way for new conceptions of human purpose. Although Newton was a religious conservative, many people would view his ideas as the backdrop for NOT viewing the universe as a stage for the creations of God. They sensed that there is more human potential than had been promised by Christian free will.

The Growing Appeal of Science The achievements of science completely transformed its social role. After long being suspect among leaders of society, science now became respectable. By the beginning of the 18th century, scientists frequented the best salons, the scientific academies gained public support as they sprang up all over Europe. The most famous were the Royal Society of London (1662) and the French Academy of Science (1664). Most academies published journals that circulated widely. Scientists and would-be scientists carried on voluminous correspondence, developing a cosmopolitan community with its own language, values and common beliefs. Rising enthusiasm on the public fringes of the scientific community was matched by a mania among leaders of society. Frederick the Great dabbled in scientific experiments, as did hundreds of bored nobles, wealthy merchants and progressive minded craftsmen. Kings endowed observatories; cities founded museums; well to do women helped establish botanical gardens; and learned societies sponsored well-attended lectures. Scientists became respected heroes. Giordano Bruno was burned for heresy in 1600 by the Inquisition; Galileo was hounded by the Church through most of his productive years and ended his life under house arrest; but Newton received a well-paying government position.

For many, science was a practical tool, ensuring profit and progress. Since Bacon’s time, some had foreseen a great future when science would solve many problems in agriculture and medicine. By 1700 science was being applied to the draining of mines, pumping water, irrigating fields, drying fibers, producing gunpowder, manufacturing pottery and building ships as well as in navigation.

Discoveries during the Scientific Revolution would usher in the Industrial Revolution. But first it would call into question the role of God in directing human affairs...the Enlightenment. The Impact of Science on Philosophy: The Enlightenment

Enlightenment. The term Enlightenment, as used by historians, describes one aspect of 18th-century thought and life. It is usually applied to the often radical philosophy of the age, particularly in England, Italy, and Germany but most of all in France. In its strictest sense, Enlightenment characterizes the efforts by certain European writers to use critical reason to free minds from prejudices, unexamined authority, and oppression by church or state. It is, however, difficult to limit the use of the term to one group or to a definite time. Although the Enlightenment embodied elements that clearly were represented in earlier periods, these elements are distinguished in the Age of Enlightenment by their peculiar union, their strength and influence, their diffusion, and their domination of intellectual life. The character of the Enlightenment is contradictory and still controversial.

Characteristics The Enlightenment was marked by a questioning of tradition and a growing trend toward individualism, empiricism, and attempts at scientific reasoning. Committed to freeing human minds from the oppression of dogma and authority, the Enlightenment especially challenged theology and the church. Ultimately, however, all institutions of the ancient regime inevitably became involved, and the movement's ramifications thus were religious, political, scientific, moral, and even aesthetic. The characteristics of the period were most highly visible in France. Only in France was there an organized movement (le parti philosophique—the philosophes) acutely aware of its goals and determinedly combative. The watchwords of the philosophes were reason, tolerance, and progress; their enemy, the status quo.

These general characteristics notwithstanding, the Enlightenment was a diffuse phenomenon. Enlightenment thinkers included atheists, deists, and liberal Christians. Despite agreement on problems and on certain aims, the application of critical reason to these questions led inevitably to attempts at reconstruction in all domains of life, and the results were diverse, contradictory, and often incoherent.

In France the substitution of secularism for the Christian worldview was at the core of the movement, although religion was usually considered a social and moral necessity for the generally despised common people. In England and elsewhere, however, deism coexisted relatively easily with a liberal Christianity. Still, the Christian interpretation of history, with its concepts of the fall of humanity, redemption, grace, and eternal salvation, was generally rejected. An individual's right to direct their own destiny insofar as they were able was asserted even when a vague belief in the power of a guiding deity was retained. The reordering of society for happiness on earth through laws and education became the goal.

Scientific progress and empirical methodology bolstered the new faith of Deism. The pagan spirit, revived during the Renaissance; the insecurity created by the Copernican theory that the sun, not the earth, was the center of the universe; the probing of human nature by Machiavelli, Montaigne, and others—all were further refined in the Enlightenment to challenge the Christian concepts of the world, the state, and humankind.

The new orientation notwithstanding, rationalistic, speculative, and deductive modes of thought characteristic of early Christian writers remained dominant. Unsupported universals abounded, and systems assumed to be valid were created both by the philosophes and by some English thinkers, such as Shaftesbury. General truths were sought about an entity called "Man." Conclusions were rationally "demonstrated" rather than induced from hard facts or put to the test of experience. History was commonly considered a succession of deviations from some unstated norm. The self-critical aspect of scientific method was largely ignored.

Whatever thinkers unconsciously retained from their Christian heritage, the conclusions and the spirit of the Enlightenment were non-Christian or anti-Christian. Thinkers consciously returned to Plato and Aristotle for a rational theory of government. They looked to Plutarch, Cicero, and Seneca for a moral natural law, and they adopted a materialistic theory of the universe from the atomism of Democritus and Lucretius.

Forerunners of the Enlightenment In this return to pagan attitudes, the philosophes continued a trend already developed in the scientific materialism of Descartes and Gassendi in the 17th century.

In England the Enlightenment thinkers drew on the new spirit of rationalism and naturalism expressed by Hobbes, Shaftesbury, and Mandeville, all of whom greatly influenced French philosophers. Hobbes's pessimistic view of humanity, Shaftesbury's optimism and altruism, and Mandeville's cynicism and egoism each had proponents in both countries. The most significant 17th-century English figures, however, were Locke and Newton. Locke's psychology overthrew Descartes's theory of innate ideas by attributing the origin of ideas to sensations inscribed on the blank slate of the mind. Newton's simple and encompassing theory of gravitation had a vast impact. The universe came to be regarded as a machine reducible to mathematical laws that humans could understand. Newton also inspired the philosophes' search for a simple, rational law of human nature and social life, a search leading for many to the principle that the drive for happiness and pleasure dominates all else.

Other thinkers who influenced the Enlightenment included Leibniz and Spinoza. Leibniz saw the universe as composed of an infinite number of units of force, called monads. Although these monads do not interact, each one individually reflects the entire universe. This concept was applied by 18th-century materialists to material atoms. Spinoza's politics and biblical criticism were misconstrued by the philosophes as potentially supportive of a materialist philosophy.

Fontenelle and Bayle were the major heralds of the Enlightenment in France. Fontenelle popularized the Copernican system and interest in science, and he denied the existence of an omnipotent God. He saw humanity as motivated by self-interest and desire for fame. Bayle's profound influence was exerted particularly through his Dictionnaire historique et critique (1697; An Historical and Critical Dictionary, 1710). Bayle concluded that God and religion are not socially necessary. Though rational moral beings, humans act irrationally and immorally, enslaved by passions and self-interest. Bayle emphasized a problem that drew much attention in the 18th century—the problem of evil in a world created by a God who apparently is either evil or impotent.

Despite these compelling early influences, the philosophic movement in France was slow in gaining momentum in the early part of the 18th century. It was prodded along by two masterpieces: Montesquieu's Lettres persanes (1721; Persian Letters, 1722), which satirized French institutions and pleaded for reason, justice, and toleration; and Voltaire's Lettres philosophiques, known also as English Letters (English-language version, 1733; French-language version, 1734), which described English literature and thought and English liberty and toleration.

Extent of the Enlightenment By the mid-1740s there existed a corps of fighters for Enlightenment ideas, and the movement had taken shape in skirmishes with the "establishment." This period of great works and battles lasted until 1770.

Scientific Developments. Further impetus was provided by developments in science. One speculative problem concerned the origin and nature of life. While some deists engaged in semimystical speculation, the major trend was toward materialistic, sometimes mechanistic, explanations positing that organisms are dynamic, changing systems amenable to the principles of the physical sciences. La Mettrie's L'Homme machine (1748; Man, the Machine, 1750) was the first systematic treatise on materialism. It explained the body as an automaton and described thought as the result of a complex organization of matter. Anticipating modern genetics, Maupertuis attributed primitive desire, aversion, and memory to genetic particles. In 1749 Buffon published the first three volumes of his monumental (36-volume) Histoire naturelle ("Natural History"). Buffon contended that nature is a knowable order of phenomena that can be formulated into laws independent of God and metaphysics.

Philosophical and Sociological Concepts. Also published during these years were Montesquieu's De l'esprit des lois (1748; On the Spirit of Laws, 1750) and Diderot's Lettre sur les aveugles (1749; An Essay on Blindness, 1750). The latter described in materialistic terms a purposeless, godless universe that provided no metaphysical base for human morality. In 1749, too, the great collective work of the Enlightenment, the Encyclopédie, was launched by Diderot and d'Alembert. Published between 1751 and 1772, the Encyclopédie preached the idea of progress through moderate change. It criticized existing institutions and championed the arts and crafts and a liberal bourgeois society.

As significant as this work was, its philosophy was moderate. Other contemporary ideas were much more radical, such as those expressed by Jean Meslier, an atheistic priest, in his nihilistic and anarchistic "Testament." Influenced by Locke, Condillac, in Traité des sensations (1754; Treatise on Sensations, 1930), described human psychological processes as stemming from sensations. This opened the way for Helvétius's reduction of morals to self-interest in De l'esprit (1758; Essays on the Mind, 1807) and for Rousseau's plan for behavioral control. Both imply that ideas and conduct can be controlled by conditioning. Rousseau's radical critique of existing societies as preventing humans from becoming social beings is found in his scandalous but provocative Discours sur les sciences et les arts of 1750 (Discourse on the Sciences and the Arts, 1751) and in his Discours sur l'origine de l'inégalité (1755; Discourse on the Origin and Foundations of Inequality among Men, 1761), in which he contended that men, innocently egocentric in the state of nature, become aggressive, deceitful, and alienated in society.

From 1770 on, radical theories were expressed more boldly. D'Holbach's Système de la nature (1770; The System of Nature, 1797) was a sensational statement of uncompromising atheistic materialism. Voltaire, meanwhile, had been putting out a stream of propaganda against the church and intolerance, stressing economic, social, and political reforms.

Economics. In economic thought, "physiocrats" such as Mirabeau demanded laissez-faire policies on the grounds that the natural order harmonized conflicts of self-interest. They held land to be the only real wealth. Smith, in his The Wealth of Nations (1776), placed value on labor but agreed with the laissez-faire theory. Others, including Diderot, opposed physiocratic laissez-faire dogmatism and demanded government regulation of wheat.

History. The Enlightenment also renewed interest in historiography. Careful documentation marks the work of Gibbon, Hume, and Voltaire, all of whom broadened historiography to include social, economic, and cultural life. They excluded the notions of providence and final causes, judging the past and seeking to use it as a source of lessons and even propaganda for the present. As literary artists, they believed that history should re-create the past—not merely dig out facts but explain causes.

Aesthetics. Aesthetic thought was marked by abstract questions such as the nature of taste, beauty, the sublime, imagination, and creativity and by speculation on the relations among the arts. The principal trend was away from rigid classicism, first toward greater emphasis on pleasure and emotion and later toward sentimentality and moralizing. These attitudes were applied to literature as well as art, by Diderot in France and Mendelssohn in Germany. Diderot and others investigated the question of art as imitation. In Germany, Lessing attempted to define the limits and relations of the several arts.

Morality. Whereas aesthetics was tangential to the core of the Enlightenment, the problem of moral values was central. Revelation and traditional Christian doctrine were rejected, yet deists, such as Voltaire and most British moralists, looked to God as the ultimate guarantor of moral values. Still, they often veered from natural law toward utilitarianism. The demand for happiness and pleasure set the standard for morality. Hume and Diderot and his fellow Encyclopedists looked for the roots of morality in human nature, not in the universe. Sundry novelists and dramatists throughout the 18th century increasingly stressed the human potential for evil and need for self-affirmation through aggression, domination, power, and prestige.

The moral problem centered on the exaltation of nature as norm. "Nature" meant almost anything—sexual modesty to Rousseau, sexual license to Diderot. Most of the philosophes, Rousseau excepted, regarded society as natural; as moralists, they supported its demands. The problem lay in the conflicting ideas of pleasure-happiness—nature's highest value—and "virtue," not in a Christian but in a social sense. The philosophy of determinism also undermined the ideas of merit or blame and punishment. To resolve the conflict, some French writers argued that virtue and happiness were equivalent, admitting that otherwise a concept of virtue would be invalid. Disregarding intention and conscience, utilitarianism placed the locus of moral value in the social effects of acts.

While numerous thinkers recognized and opposed the threat of immoralism, a few, such as Meslier, La Mettrie, Diderot, and de Sade, entertained or accepted the unlimited demands of the individual. They denied the validity of sacrifice as a social imperative, since accepting this imperative was an indirect return to the self-denying position of Christianity. Nature's law was to them the law of the strong. Enlightened self-interest and the virtue-happiness equivalence were illusions or hypocrisy.

(Some of the Philosophes took an extreme position as science advanced. Individuals, they said, would become increasingly capable of good, until at last they reached complete harmony with nature when they would be judged perfect. Thus, they concluded, humans are not only good, but perfectible. No doctrine of the Enlightenment was more controversial than Human Perfectibility. It runs counter to Christian belief and is hard to reconcile with much of history. The ablest thinkers of the day did not prescribe to this extreme view, but they joined with others in working tirelessly for social improvement.)

Government. Besides the problem of moral values, the other great challenge posed by the Enlightenment concerned government. Primitivism, anarchism, collectivism, enlightened despotism, and even dictatorial government were all espoused by various writers, according to their view of human nature. Following the psychology of the time, it was generally thought that humankind could be shaped by government, law, and education. While a few primitivists wished social demands to follow natural demands, other utopians imagined collectivist, noncompetitive societies, generally with regimentation, thought control, and the reshaping of the individual. Rousseau, in particular, devised techniques of behavioral control. These included censorship, "education," spying and denunciation, deception, emotional propaganda, and complete unquestioning commitment to the general will, which would socialize humankind and end the "war within him"—and among humans. A larger body of writers—including Montesquieu, Voltaire, the Encyclopedists, and Condorcet—favored individual liberty and representative government. Moderates, who usually spoke for the rising bourgeoisie, sought reforms, a limited monarchy, and an end to oppression. For example, Beccaria campaigned to reform criminal law and put an end to legally sanctioned torture. Idea of Progress. Clearly the idea of progress was omnipresent in the Enlightenment. Yet the generalization that it was an age of optimism, although familiar, is false. A few optimists regarded a nigh-perfect world as assured. Rousseau and others knew they were merely speculating. Pessimism about human nature ran deep, beginning with Bayle, and its frequent presence in the drama and the novel reflects one mood of the time. A belief in meliorism more accurately characterizes the Enlightenment, since most thinkers believed that although human nature would not change, reform and a better, more rationally planned society were possible. Most thought that science would continue its forward march indefinitely. On the other hand, Montesquieu and Voltaire essentially were historical pessimists who believed that all societies decline, although both thought that lessons could be derived from history. Buffon, seeing nature as the enemy of humanity, considered progress to be precarious. On the question of progress—as on every matter except religious toleration, the pursuit of happiness considered as a goal, and the notion that reform was needed—there was little agreement.

Reaction and Long-Term Effects Reaction against the trends of the Enlightenment set in even before the excesses of the French Revolution—for which it was not responsible—brought it into disrepute. The greatest philosopher of the 18th century, Kant, challenged the bases and suppositions of the Enlightenment. He sought a new structure for knowledge and aesthetics and rejected especially the Enlightenment's utilitarian ethics in favor of a categorical moral imperative.

Still, the Enlightenment's legacy was substantial. Sensualist psychology and the idea of conditioning human development through societal laws became part of 19th-century thought. The scientific speculation of the 18th century, although it presaged future events, largely had little lasting value except in its materialism and in the dawning idea of evolution. Moral speculation, however, produced the utilitarianism of the 19th century, as well as nihilism, which remained a powerful undercurrent and reemerged after World War I. Similarly, the development of the tenets of both liberal democracy and totalitarian democracy (or collectivism) was furthered during the Enlightenment. Franklin, Jefferson, Adams, and Madison found in French and British political and moral speculations ideas on political and civil rights, a rational and just society, representation, and popular sovereignty as expressed in suffrage. Marx, another spiritual son of the Enlightenment, galvanized its speculative protototalitarianism with the doctrines of class struggle, economic determinism, and dialectical materialism.

The Enlightenment is significant above all as a revolutionary period. It destroyed myths by which people lived and then proposed new myths of its own, many of which came to be challenged in the second half of the 20th century—by feminist thinkers, among others. The Enlightenment completed the task of destroying the security of the Christian cosmos and the moral, metaphysical, and political structure it supported, while proposing various constructive alternatives. It uncovered and examined the darker side of human nature and the deepest human dilemmas encountered in facing the universe and maintaining a civilization. It sought remedies in human nature itself and held that humans should, as far as nature allowed, control their own destinies and make their lives on earth and human betterment their highest goals.

Lester G. Crocker University of Virginia Crocker, Lester G. "Enlightenment." Encyclopedia Americana. 2007. Grolier Online. 1 Feb. 2007 . ------