ABSTRACT
Obstacles to progress may be within the science itself or outside. You can look at the problem psychologically, politically, or sociologically. I, myself, in choosing to talk about progress, have, I think, a slightly easier task than those who will talk of its obstacles, because progress in science is presumably something that can be defined in internal terms intrinsic to science. My thesis will be that the concept of progress in science is not a simple concept. You might well say that it does not need a long lecture to explain that something is not simple. Nevertheless, I will try to dispel any prejudices that it might be simple. To start then, I think I should try and define what science is. This is a subject in which I am a whole-hearted follower of Karl Popper and his criterion of demarcation, which is why I feel so honoured to have been asked to start a series which will be completed by Karl Popper himself, for whom I have such admiration.
