French psychoanalytical theorist who' s influence continues today most notably advocated by Slavoj Zizek.
Lacan in turn, reinterprets Freud and in particular, the difficult concept of the unconscious. Lacan links language and the unconscious and suggests that the unconscious is structured like a language. This resonates with some of Freud's ideas as articulated in Jokes and their Relation to the Unconscious and his earlier work on The Interpretation of Dreams.
Lacan is also known for his theory of the Mirror Stage. This occurs in infants who at that stage develop a capacity that is evidenced by their reaction of recognition when they see their own image in a mirror. What is this capacity? It is a conceptual act, the establishment of 'I' (the ego) and an essential foundation for social functioning and a precursor to language. (Why do we use language? To communicate with others!)
Lacan proposes that reality for humans is comprised of a trilogy of levels the Real, Imaginary and Symbolic orders.
I see these as registers of the mind ways of knowing.
Zizek provides a useful analogy - consider the game of chess: at one level, corresponding to the Symbolic, we have the rules of the game, at another level we have the representation of the pieces as, for example, a knight or a pawn, this is the Imaginary and at the third level we have the actual game itself, all aspects of it, including the thinking of the players , the physical surroundings etc..
Language works at the level of the Symbolic and it is always influenced by the big Other.
Language is not a passive exchange - when we communicate we operate within a frame of reference (a concept from Mezirow in turn from Habbermas). Lacan reifies this as the big Other - he gives it a form that recognises how we think. For example, a religious person may process thoughts as what God would like me to say or do, or perhaps a person has a strong ideological framework as with communism - this will shape all that is uttered.
What then of the Real and the Imaginary?
The Real is usually recognised by an absence rather in the same way that we respond to a disequilibrium. We don't perceive it directly but rather through our responses.
So here's an example of my own making that gets at what I think Lacan was attempting to point to. I met a colleague recently and I said "Isn't it terrible what's been happening in Limerick yet another gangland murder yesterday"
He responded "Shocking when will it ever stop".
This is just a small part of a typical verbal exchange that takes place between people every day. Look at the levels or registers, or as Lacan would say 'orders' of the discourse.
There is the Symbolic order this comprises the words exchanged and our shared cultural understanding of, for example, what we mean when we say 'gangland' and further our shared collection of connotations for Limerick.
I would describe the Symbolic order as a form of literacy.
The next level is the Imaginary order. When I say "Isn't it terrible I am referring to a specific recent murder the most recent in a spate. I have a way of imagining a murder it's certainly a very sanitized format.
Let me call it a visualization but note that the perception may not all be visual in nature. This visualization for me is tame, very tame for a murder. I leave out a huge amount of detail - so my imagined form is constructed by me in a way that I can use it and not get too upset by it. Notice, that the Imaginary order is not a complete picture, such a picture would be unworkable in everyday life.
Now consider the Real order. This is everything that is not part of the Symbolic or the Imaginary. I call it the inconceivable. What's our way of knowing this? We indirectly detect by imbalance or absence-as in when we use the phrase 'the breakdown of law and order'. There's lots left out - the fragility of life, the sociological crisis in areas of Limerick, injustices, capacity for evil.
This is as far as I will go for now with Lacan.
There is a link to a good web site on Lacan above.