Origins of the medieval discussion: Peter Lombard

Medieval treatises on conscience were divided into two parts, one headed ‘synderesis’ and the other ‘conscientia’. ‘Synderesis’ is just a corrupted transliteration of ‘suneidēsis’ the Greek word for ‘conscience’, so the medieval distinction between synderesis and conscientia requires explanation. In the first instance, the explanation is historical. Conscience was not directly treated either by Plato or by Aristotle; the way in which it became a standard topic of later medieval philosophy was curious, almost an accident. Like many other topics regularly discussed by medieval philosophers, it came to their attention through a passage in Peter Lombard's Sentences and most of the medieval treatises on conscience are to be found in commentaries on that work.

Yet Peter Lombard does not actually discuss conscience at all: his question is how the will can be bad (2.39). As usual, he reports several answers, though, exceptionally, without pronouncing judgement upon them at the end. He notes, first, that some people distinguish two senses of ‘voluntas’, in one of which it is a power, in the other the exercise of that power (1.3). This distinction was probably inspired by a parallel Aristotelian distinction, between two senses of ‘know’, the first dispositional, but the second involving actually thinking about what one knows, as is sometimes necessary when using one's knowledge. Similarly, we each have a host of desires, but it is only at certain times that any one of them makes itself felt or that we pay attention to it, so that it is then actualised in the sense of being called to mind.