Boris Hennig

This is partly a book about Aristotle’s four causes (material, formal, efficient, and final cause), partly a systematic discussion of the relation between form and matter, causation, and teleology. Its overall aim is to show that the four causes form a system, so that the form of a natural thing relates to its matter as the final cause of a natural process relates to its efficient cause. It reaches two highly distinctive conclusions. The first is that the formal cause or essence of a thing is not a property but a generic thing. The second is that the final cause of a process is not its purpose but the course that processes of its kind typically take.

Although Descartes is often said to have coined the modern notion of ‘consciousness’, he defines it neither explicitly nor implicitly. This may imply (1) that he was not the first to use ‘conscientia’ in its modern, psychological sense, or (2) that he still used it in its traditional moral sense. In this paper, I argue for the latter assumption. Descartes used ‘conscientia’ according to the meaning we also find in texts of St. Paul, Augustine, Aquinas and later scholastics. Thus the Cartesian conscientia is, technically speaking, a shared knowledge of the specific value of our thoughts as thoughts and at the same time the cause of this value. This means that it is not itself a kind of individual knowledge, awareness, or a particular thought. Rather, ‘conscientia’ refers to the evaluative knowledge of an ideal observer

This chapter proceeds in five steps. First, we will describe and justify the structure of the traditional system of species classification. Second, we will discuss three formal principles governing the development of taxonomies in general. It will emerge that, in addition to these formal principles, a division of living beings must meet certain empirical constraints. In the third section, we will show that the traditional division of living beings into species best meets these constraints. Fourth, we will argue that a taxonomic system based on this notion of species provides a more natural alternative to the many arbitrary classifications that are possible. Hence, the traditional classificatory system is also the most natural one. Finally, we will discuss and reject an alternative account that suggests defining species solely with a view to their evolutionary history. We will argue that taxonomic trees do not depict hereditary connections but, rather, something else.