What exactly is the conscience? Here are two ingredients which together help us to understand what the Bible means by conscience.
What does conscience mean?
At the lowest level, conscience means an awareness of myself. It is very similar to consciousness, that uniquely human ability for ‘I’ to think about ‘me’. This is the origin of the word. Conscience is a word that came into english from Latin. It means something like a knowledge (‘ . . . science’) that is shared (‘con . . . ’, meaning ‘with’). The family of Greek words translated as ‘conscience’ in the New Testament have the same origin: the main word is syneidēsis, where eidēsis means ‘knowledge’ and syn means ‘with, or shared’. The Old English word (technically Middle English) was inwit, where wit means something like ‘knowledge’ or ‘judgment’ (rather as we speak about our wits) and in points to the inwardness of it. At the most basic level, conscience means an inward knowledge, a self-awareness, a knowledge shared inwardly with myself. It is to do with self-knowledge.
But the meaning of a word comes not just from its origins.1 Both in the New Testament and also in english, conscience has the sense not just of self-awareness, but of moral self-awareness, an awareness within myself about right and wrong. So the Oxford English Dictionary begins one of the meanings of the word as follows:
The internal acknowledgement or recognition of the moral quality of one’s motives and actions; the sense of right and wrong as regards things for which one is responsible . . .
The New Testament includes this sense in its use of the word.
There is no separate word for conscience in the Old Testament, but the idea is still there and is often expressed by the word heart, which includes this intellectual dimension. Conscience makes me aware in my mind that this is right and that is wrong. Conscience takes the universal principles of right and wrong that I know, and applies them to my particular circumstances. For example, I know it is right to honour my parents. So, when my elderly parents need me to do some shopping for them, my conscience deduces for me that it would be right to help them if I can. That is a trivial example. Others are much more difficult, especially when there seems to be a clash of obligations. Conscience begins with thinking about what would be right to do, with making reasoned judgments about what is right and wrong behaviour.
1) This is to say, etymology (a word’s derivation) cannot determine meaning. For example, a ‘cupboard’ is not a ‘board’ upon which you may put a ‘cup’, even if it may once have meant that.