ABSTRACT
Four major conceptions of science may be discerned: scientific positivism, critical rationalism, conventionalism and scientific realism. These labels do not have a uniform use in philosophy of science and their meanings are often strongly contested. This chapter describes the author's view of them, suggests how they are related and offers some comments and criticisms. The first, scientific positivism, is of particular importance because of its very considerable influence, and the fact that the others may all be seen in relation to it, as both developments and critiques of it. Science and the philosophy of positivism are closely linked. Positivism has always held science to be of central importance, even to the extent of reducing philosophy to philosophy of science. Where the positivists are generally hostile to philosophy that goes beyond the logic of science, Popper is keen to assert both the meaningfulness and the importance of philosophy.
