One of the most remarkable attributes of mankind has been the ability to make progress in many technical fields despite the absence of a complete understanding of the underlying mechanisms. For example, we find ourselves in the midst of the electronic age and an electronic `revolution', yet with little understanding of just what is an electron. A similar situation exists in thermodynamics, where the technology has advanced greatly over two centuries, but many of the fundamental questions remain in dispute. Here we are perhaps on firmer ground than with the underpinnings of electron structure, on the one hand; but the discussions carry a greater emotional burden, on the other, and thus one faces greater risk in re-opening them. The point of science, nevertheless, is to understand eventually the basic mechanisms in complete detail, aside from technological questions, so that it is important to continue to debate these issues in the hope of achieving greater clarity. Here we shall return to perhaps one of the most interesting and controversial questions of all, the origins of entropy and irreversibility. Section I attempts to establish common ground with respect to a number of definitions and conceptual scenarios, as well as to pose some of the questions and issues as the author sees them. In Section II we survey the traditional views about many of these, and discuss their resolutions.
[Published in Open Systems & Information Dynamics 1, 183 (1992)]
