Antonio Damasio (1999, 230-33) elucidates the intimate connection between conscience and consciousness. He points out that whereas English and German have separate words for them, the Romance languages typically use the same word for both, so that one relies on context to determine which meaning is intended. In order to ‘do the right thing,’ one must in the first place be conscious in a distinctively human sense, which Damasio calls extended consciousness. This endows us with a range of abilities not shared with other animals.
Among this remarkable collection of abilities allowed by extended consciousness, two in particular deserve to be highlighted: first, the ability to rise above the dictates of advantage and disadvantage imposed by survival-related dispositions and, second, the critical detection of discords that leads to a search for truth and a desire to build norms and ideals for behavior and for the analyses of facts. These two abilities are not only my best candidates for the pinnacle of human distinctiveness, but they are also those which permit the truly human function that is so perfectly captured by the single word conscience.
— Damasio (1999, 230)
The concept of conscientia is the original root concept from which all later terminologies in Roman languages and in English have developed. It is derived from cum (‘with,’ ‘together’) and scire (‘knowing’) and in classical antiquity, as well as in scholastic philosophy, predominantly referred to moral conscience or a common knowledge of a group of persons, again most commonly of moral facts. It is only since the seventeenth century that the interpretation of conscientia as a higher-order knowledge of mental states begins to dominate. Because cum can also have a purely emphatic function, conscientia also frequently just means to know something with great certainty. What the major Greek precursor concept of συνειδήσις shares with conscientia is the idea of moral conscience.
— Metzinger (2003, 171n)
The Greek συνειδήσις, like Latin conscientia, compounds a verb meaning ‘to know’ with a prefix meaning ‘together with.’ The shorter word σύνεσις, literally ‘a coming together,’ could also mean ‘conscience’ as well as ‘sagacity’ (LS). In classical Greek the verbal form of suneidesis was sometimes used with a reflexive pronoun, so a literal translation would say ‘I know with myself’ (that some action is good or bad). This highlights the intimate connection with self-consciousness (often called simply ‘consciousness’ in English).
Julian Jaynes (1976) developed a hypothesis that the Greeks of classical times were the first humans to be conscious – that is, the first to recognize that the guiding ‘voices’ which they heard were coming from themselves. According to Jaynes, humans before this point hallucinated these voices coming from distant or departed authority figures, or from statues of them, when in fact they were generated by the right hemisphere of the brain; thus they had ‘bicameral minds,’ divided between thoughts or ‘voices’ which they took to be their own and voices which they heard as coming from Others. This way of seeing (or rather hearing) things broke down when the Greeks internalized the voice of conscience, and the result was what we now call ‘consciousness.’
According to Damasio,
the nonconscious neural signaling of an individual organism begets the proto-self which permits core self and core consciousness, which allow for an autobiographical self, which permits extended consciousness. At the end of the chain, extended consciousness permits conscience.
— Damasio (1999, 230)
Damasio remarks that humanity has always been concerned with conscience, but the ‘preoccupation with what we call consciousness is recent – three and a half centuries perhaps – and has only come to the fore late in the twentieth century’ (231). Science is thus working its way from the basic level (conscience) back toward the beginning of this ‘chain’ of developments. For a closely related study focussing on the evolution of morality, see Goodenough and Deacon (2003).