Three Concepts of Time I. Time as a Many Tiered Construct 1. The Problem Situation 2. The Objectivity1 of Time 3. The Objectivity2 of Time 4. The Problem of ‘The Present’ II. Temporal Processes 5. The Interplay of Chance and Causality 6. Thermodynamics and the Temporal Asymmetries 7. Temporal Ongoings in Biology 8. Time and Consciousness References. The existence of so many strangely puzzling even contradictory aspects of time is due I think to the fact that we obtain our ideas about temporal succession from more than one source from inner experience on the one side and from the physical world on the other. Time is thus a composite notion and as soon as we distinguish clearly between the ideas deriving from the different sources it becomes apparent that there is not just one time concept but several. Perhaps they should be called variants but in any case they need to be seen as distinct. In this book I shall aim at characteri­ sing what I believe to be the three most basic of them. These form a sort of hierarchy of increasing richness but diminishing symmetry. Any adequate inquiry into time is necessarily partly scientific and partly philosophical. This creates a difficulty since what may be elementary reading to scientists may not be so to philosophers and vice versa. For this reason I have sought to present the book at a level which is less advanced than that of a specialist monograph. Due to my own background there is an inevitable bias towards the scientific aspects oftime. Certainly the issues I have taken up are very diffe­ rent from those discussed in several recent books on the subject by philoso­ phers.