The bewildering confusion prevailing in contemporary philosophic and scientific literature with regard to the meanings of the words ‘causation’, ‘determination’, ‘causality’, and ‘determinism’, obliges to begin by fixing the terminology. This chapter looks at the different uses of ‘causation’ and ‘determination’, two concepts that are frequently regarded as equivalent although some philosophers have acknowledged their difference. But in science the most frequent use of the word ‘determination’ that is relevant to our concern seems to be that of constant and unique connection among things or events, or among states or qualities of things, as well as among ideal objects. Any clear-cut distinction among types of determination involves the assumption that they are irreducible to one another, that is, that none of them can be regarded as a mere mixture of other forms of lawful production, every one of them being characterized by a peculiar newness of its own.