Philosophy of biology has a long and honourable history. Indeed like most of the great intellectual achievements of the Western World it goes back to the Greeks. However until recently in this century it was sadly neglected. With a few noteworthy exceptions someone wishing to delve into the subject had to choose between extremes of insipid vitalism on the one hand and sterile formalizations of the most elementary biological principles on the other. Whilst philosophy of physics pushed confidently ahead the philosophy of biology languished. In the past decade however things have changed dramatically. A number of energetic and thoughtful young philosophers have made real efforts to master the outlines and details of contemporary biology. They have shown that many stimulating problems emerge when analytic skills are turned towards the life-sciences particularly if one does not feeI con- strained to stay only with theoretical parts of biology but can range over to more medical parts of the spectrum. At the same time biology itself has had one of the most fruitful yet turbulent periods in its whole history and more and more biologists have grown to see that many of the problems they face take them beyond the narrow confines of empiric al science: a broader perspective is needed.