It is my aim to introduce the themes brought up by Paul Feyerabend, Ernan McMullin and Bas van Fraassen by means of a brief overview — partly historical and partly systematical — of the realist and empiricist positions with respect to science. My selection and presentation of topics has been influenced by the wish to make a connection with some of the points raised in other contributions to this volume, especially the earlier chapters. (What do the results of modern physics tell us about reality?)

The traditional view of science

In the traditional Aristotelian view, science is the unique enterprise in which humanity discovers fundamental truths about the world in a systematic, rational, way. According to this view the result of scientific investigation is knowledge, to be contrasted with mere opinion; knowledge is defined as provably true, fundamental and universal. There are a number of characteristic ingredients in this conception.

Realism

Inherent in the traditional view is the realist position that science deals with an independent external world, which for its greater part is not accessible to the human senses but can nevertheless be discovered, investigated and described. Science actually focuses on these unobservable traits of the world, in order to give fundamental explanations.