Most philosophers who have studied consciousness know that the word derives from Latin, and that the modern usage can be traced to John Locke. But there is an interesting aspect of the etymology that is not so widely known, and I think is worth understanding—it tells us that the sense of paradox that many people feel when thinking about consciousness, the sense of what Douglas Hofstadter calls a “strange loop”, can be traced all the way back to its Latin and Greek origins.
The English word “conscious” was taken directly from the Latin conscius, which derives from the roots con- (“together”) + scire (“to know”). The Latin word did not mean what we mean by “conscious” today, though. The basic meaning was to know with—in other words, to hold knowledge that is shared with another person. Instead of our implication that knowledge is held within one person’s mind, the implication was that conscius knowledge is held in common by multiple individuals. Thus the Latin conscius essentially denoted a relationship, the relationship of sharing knowledge (C. S. Lewis, 1990).
All of that is widely known, but what is not so widely understood is that the word could also be used reflexively. There were many occurrences in Latin literature of the phrase conscius sibi, which translates literally as “to share with oneself the knowledge that . . .” (Sibi means “to oneself”.) When Latin literature was translated into English, this construction was often rendered as “conscious to oneself” or “conscious unto oneself”, for example “I am conscious to myself that . . .” or “he was conscious unto himself that . . .”, or similar variants. The idea of sharing something with oneself is meaningless in a literal sense, so it is clear that the intended meaning must have been figurative. Judging by context, conscius sibi was a way of conveying the idea of knowing that one knows, as our modern Engish word “conscious” does. Thus the true precursor of the English word “conscious”, as it is used today, is not so much the Latin word conscius as the phrase conscius sibi.
Actually the history can be traced back even farther. The Latin conscius itself derived from a Greek word that can be transliterated syneidesis. This word was used as early as the 5th century B.C., and appears in the Bible, where it is usually translated as “conscience”. It’s basic meaning, though, was “shared knowledge”, just as for the Latin word. And like the Latin word it could be used reflexively, as expressed by the phrase synoida emautoi, to mean knowledge shared with oneself (Schinkel, 2007, p. 131).
Although the idea of sharing knowledge with oneself is paradoxical in a logical sense, it isn’t difficult to guess how it arose. Almost all of us, when we think, have the impression that we are holding a conversation with ourselves. Our language-generating system encodes a thought as a sentence or quasi-sentence, then passes it subvocally to our language-receiving system, which parses it; this continues in an endless cycle. This internal conversation gives us the sense of being split into two parts, speaker and listener, which share knowledge.
In the English language, the first uses of the word “conscious” came during the 1500s. At that time the majority of literate people knew Latin, and consequently the original meaning of the English word matched the Latin meaning—that is to say, the English word like its Latin forebear had the connotation of shared knowledge. In Leviathan Hobbes wrote, “Where two, or more men, know of one and the same fact, they are said to be Conscious of it one to another.” And Bishop South, writing about friendship in his Sermons published in 1664, said, “Nothing is to be concealed from the other self. To be a friend and to be conscious are terms equivalent.” Those sentences look bizarre to us today, of course, but they are straightforward renditions of the original Latin meaning.
It was some time before English equivalents of the reflexive form conscius sibi showed up. We begin to see them somewhere around the year 1600, rendered as “conscious to oneself” or “conscious unto oneself”. Archbishop Ussher in 1620 wrote of “being so conscious unto my selfe of my great weakness”, for example. This reflexive phrasing continued to be used in theological writing—the last bastion of Latinity—for at least another hundred years.
When “conscious” first entered the English language in the 1500s, it was an arcane, artificial word used mainly by poets, and mainly in a figurative way. In the beginning, as I said, it kept its Latin connotation of shared knowledge, but was often used to indicate knowledge shared between a person and an inanimate object. For example, a poem from the 1500s called Ode to a Water Nymph, by a certain Mr. Mason, has the verse:
Whither, ah! Whither art thou fled?
What shade is conscious to thy woes?
Here the shade (meaning shadow, I think) is conceived of as sharing knowledge of the nymph’s woes. And in Paradise Lost, Milton has the line:
So all ere day-spring, under conscious night, secretly they finished.
Here the night is imagined as knowing what the characters were conniving at.
When “conscious” was not being used in a figurative way, it most frequently was used to indicate awareness of wrongdoing, in other words, having a conscience or having something on one’s conscience. During the middle of the 1600s this became its primary connotation. In the Universal Etymological Dictionary compiled by Nathan Bailey and published in 1675, the definition given for “conscious” is inwardly guilty, privy to one’s self of an error, also knowing from memory. The definition given for “consciousness” is simply guiltiness. An example of this usage is the title that Richard Steele gave to his 1723 comedy: The Conscious Lovers. The title means the lovers with a conscience, that is, lovers who behaved in a more conscientious way than the characters in most comedies of the period. (To everyone’s surprise, the play was actually popular.)
In the 1600s, though, a gradual shift apparently occurred, in which the most prominent usage became “conscious to oneself”, while other uses faded away. There then occurred a transition of a sort that is common in the evolution of language: since “conscious” was rarely used except in the form “conscious to oneself”, the “to oneself” part began to feel redundant and began to be omitted. Thus “conscious”, all by itself, came to be used as an equivalent of conscius sibi rather than merely of conscius per se. This transition is already implicit in Bailey’s definition, but shows up most clearly in 1690, in John Locke’s Essay concerning Human Understanding. Locke explicitly defined consciousness as the perception of what passes in a man’s own mind.
Locke’s definition was so clearly stated, and his Essay so widely read, that his usage was adopted, with minor modifications, by most philosophers of the next generation. Thus Clarke in 1707 wrote, “Consciousness, in the most strict and exact Sense of the Word, signifies . . . the Reflex Act by which I know that I think, and that my Thoughts and Actions are my own and not another’s.” And Reid in 1785 wrote, “Consciousness is a word used by Philosophers, to signify that immediate knowledge which we have of our present thoughts and purposes, and, in general, of all the present operations of our minds.” These are basically elaborations of Locke’s definition.
In summary, the basic point is that the Latin conscius did not mean anything like awareness. If it could be equated with any single English word, that word would probably be communication. It was frequently used, though, in the sense of communicating with oneself, and it is that usage that ultimately evolved into the modern meaning.
The most interesting aspect of this, to me, is that Locke’s notion of consciousness derives ultimately from the paradoxical idea of sharing information with oneself. That is paradoxical in the sense that sharing anything with oneself is paradoxical—it isn’t really sharing at all. (Teacher: “Johnny, you know that if you bring candy you have to share it.” Johnny: “I am, Mrs. Smith. I’m sharing it with myself.”) This sense of paradox has become obscured in many modern treatments, but it still lurks there beneath the surface.
C. S. Lewis (1990). “Conscience and conscious”. Studies in words. Cambridge University Press
Anders Schinkel (2007), Conscience and Conscientious Objections, Amsterdam University Press.
“Conscious”. Oxford English Dictionary
Footnote: The material here is derived from a longer essay called “Consciousness” as a Word. I don’t speak Latin, and my knowledge of the language is primitive. I have asked several Latin-speakers to check the assertions I make here, but I still don’t have 100% confidence in them. If I have screwed anything up, I would very much appreciate being told about it.