The shift in the western mind from the medieval to the modern was underpinned by the growth of science. However a two hundred year long intellectual battle was to take place between the established Church and the emerging empiricism, before the Enlightenment could flourish. Nicolaus Copernicus (1473-1543) challenged the view that the Earth was at the centre of the universe. He suggested that the observational evidence would be better explained by the theory that the earth orbited the sun. Francis Bacon (1561-1626) argued for the use of experiment rather than deduction as a means to increase knowledge. Johannes Kepler's (1571-1630) employment of observation and mathematics enabled him to supplant the Pythagorean (ancient Greek philosopher Pythagoras' (c. 530 BC)) theories of perfect heavenly spheres by showing how planets moved in ellipses. Galileo Galilei (1564-1642) was placed under house arrest for agreeing with Copernicus.
Despite resistance from the religious authorities, the success of science in explaining and predicting the natural world could not be ignored. René Descartes (1596-1650) thought he had found a rational foundation for science based on his arguments for his own existence and the existence of god. God, he argued, would not deceive our senses. This felicitous reconciliation between Cartesian rationalism, a belief in God and the support for empiricism did not survive for long.
Isaac Newton's (1642-1727) advances in physics based on his empirical and inductive methods were hugely influential to the philosophers of the Enlightenment. Immanuel Kant (1724-1804) thought that Newton's laws could be shown to be true by reason and that the scientific approach could explain the phenomenal world (the world of appearances). He retained a dualistic view of the universe: human beings lived in a world of rationality, autonomy and morality whilst the material universe which they observed was explained in terms of cause and effect.
Auguste Comte (1798-1857) argued that human thought developed through a number of stages: mythical and religious, metaphysical and its final positive stage which was characterised by the systematic collection of observed facts. He thought that these "Positivist" methods should now be turned to the study of society. With his invention of sociology, Comte was suggesting that our knowledge of human beings could be explained using similar methods to those of the natural sciences.
Karl Popper (1902- 94) was critical of the inductive methods used by science. The empiricist David Hume (1711-76) had argued that there were serious logical problems with induction. All inductive evidence is limited: we do not observe the universe at all times and in all places. We are not justified therefore in making a general rule from this observation of particulars. Popper gives the following example. Europeans for thousands of years had observed millions of white swans. Using inductive evidence, we could come up with the theory that all swans are white. However exploration of Australasia introduced Europeans to black swans. Poppers' point is this: no matter how many observations are made which confirm a theory there is always the possibility that a future observation could refute it. Induction cannot yield certainty.
Popper was also critical of the naive empiricist view that we objectively observe the world. Popper argued that all observation is from a point of view, and indeed that all observation is coloured by our understanding. The world appears to us in the context of theories we already hold: it is 'theory laden'.
Popper proposed an alternative scientific method based on falsification. However many confirming instances there are for a theory, it only takes one counter observation to falsify it: only one black swan is needed to repudiate the theory that all swans are white. Science progresses when a theory is shown to be wrong and a new theory is introduced which better explains the phenomena. For Popper the scientist should attempt to disprove his/her theory rather than attempt to continually prove it. Popper does think that science can help us progressively approach the truth but we can never be certain that we have the final explanation.
Thomas Kuhn (1922- ) was critical of the simplistic picture that philosophers had painted of science. Kuhn looked at the history of science and argued that science does not simply progress by stages based upon neutral observations. Like Popper, he agrees that all observation is theory laden. Scientists have a worldview or "paradigm". The paradigm of Newton's mechanical universe is very different to the paradigm of Einstein's relativistic universe; each paradigm is an interpretation of the world, rather than an objective explanation.
For Kuhn the history of science is characterised by
revolutions in scientific outlook. Scientists accept the dominant
paradigm until anomalies are thrown up. Scientists then begin to
question the basis of the paradigm itself, new theories emerge
which challenge the dominant paradigm and eventually one of these
new theories becomes accepted as the new paradigm.
Paul Feyerabend thought that the superiority of the modern scientific method should not be assumed. He argued for an anarchist approach to knowledge: we cannot predict what shape future knowledge will have, so we should not confine ourselves to one universal method of gaining knowledge. Feyerabend agrees with Kuhn that the history of science is the history of different viewpoints, and for Feyerabend this means that what counts as 'knowledge' in the future may have paradigms we cannot yet know. As we cannot yet know them, we should not attempt to forbid future intellectual enterprise by attempting to define one narrow dominant paradigm of knowledge using the model of physics.
In the 20th century, Einstein's theory of relativity overthrew the Newtonian paradigm that had been dominant since the Enlightenment. This change of paradigm made philosophers aware that the fundamentals of a scientific understanding were not a static unchanging set of natural laws, rather these paradigms were human interpretations of phenomena as much dependant on the community in which they surfaced as on the nature of reality herself. Scientific explanation can no longer be looked upon as objective and neutral. At the boundaries of science new paradigms are emerging to challenge the current orthodoxy, it is an open question as to how the science of the next century will develop.