This collection brings together several essays which have been written
between the years 197 5 and 1983. During that period I have been
occupied with the attempt to find a satisfactory explicate for the
notion of tnithlike- ness or verisimilitude. The technical results of
this search have partly appeared elsewhere, and I am also working on a
systematic presentation of them in a companion volume to this book:
Truthlikeness (forthcoming hopefully in 1985). The essays collected in
this book are less formal and more philos- ophical: they all explore
various aspects of the idea that progress in science is associated with
an increase in the truthlikeness of its results. Even though they do not
exhaust the problem area of scientific change, together they constitute
a step in the direction which I find most promising in the defence of
critical scientific realism. * Chapter 1 appeared originally in Finnish
as the opening article of a new journal Tiede 2000 (no. 1 I 1980) - a
Finnish counterpart to journals such as Science and Scientific American.
This explains its programmatic character. It tries to give a compact
answer to the question 'What is science?', and serves therefore as an
introduction to the problem area of the later chapters. Chapter 2 is a
revised translation of my inaugural lecture for the chair of Theoretical
Philosophy in the University of Helsinki on April 8, 1981. It appeared
in Finnish inParnasso 31 (1981), pp.