The Decentered Subject. Yes indeed, if you don't count beatniks, short skirts, bell bottoms and boots, a Decentered Subject is one of the causes of people putting things like the word Post in-front of a word like Modernism or Structuralism. Within the Lacanian view it's not that hard, we are the fickle subjects of forces beyond our control. For a supporter of the prefixing of the word post to structural, those forces include language, social structure, discourse as well as heated argument. We, each one of us, are internally divided, there is definitely an enemy within, we are fractured, more contradictory than we are coherent. In short our well packed prelinguistic suitcase flew open years ago when we were running to catch the train.
Source of Meaning. We, as a you and an I, might make the odd word up like cuddlebunny, but you or I, neither of us are the origin of meaning. We are closer to a repository of crossword clues. The meaning that flows through us is more like an effect, as in the "effect of the weather is a change in my mood" and safe to say this effect is a consequence of using language in a society that talks. An English speaking pig goes Oink, a Polish pig offers a full blown Chrum and that's just the way it is.
Jacques Derrida, made a word up so that he could encompass the idea of differ and defer. Differ as: not the same as each other. And Defer as: putting off so that further consideration might occur. Derrida's word, différance, is kind of like the phrase "Give it time, let it come by freight." And why, because when the subject is decentered there is no transcendental center, or confident and obnoxious decision maker, which leads to an instability baked into the structure of language that according to poststructuralist thinkers you and I should take for granted and relish, rather than put on uniforms, arm ourselves and march around with sticks pointing at people.
In 1966, Jacques Derrida and Jacques Lacan, both ambitious, career orientated young males with great hair and Napoleonic eyes had charged themselves with the immense task of introducing French Poststructuralist Thought to Baltimore's John Hopkins University at a conference called "The Languages of Criticism and the Sciences of Man." In Baltimore, Derrida and Lacan, spent much of their time addressing what happened to your writing when you died, which for the pragmatic children of William James might have been a little on the psychedelic side. But Derrida had a point to make. When you are alive you're present, you're there, ready with questions, ready with answers, ready to maintain a presence. When you're dead you're not there. Which means that metaphysically, you being alive are connected to the symbolic order, you are part of meaning now, but when you're dead you yourself are not part of meaning, which is why the title of your book or play, along with any memory of you, is a tombstone. Dream on Shelley, go ahead weep for Adonais, send thousands more to detention, it still doesn't mean you're not a couple of bones and a few teeth under a stone slab in Rome, Italy.
Lacan and Derrida's most wonderful debate, some might say clash, had to do with how the Symbolic Order treated the word Signifier. The debate has been referenced as "The Purloined Letter Debate of 1975." The Purloined Letter is a short story by Edgar Allan Poe, it's in the detective story from Paris genre. The famous detective August Dupin had got himself involved in a whole series of tricky situations that involved searching for clues about a suggestive and possibly gossipy letter that had been removed from the Queen's private quarters and replaced with an innocent how you feeling time of day letter that had nothing salacious or remotely interesting to say about anything.
For our two heroes, Lacan and Derrida, Poe's short story was about what the letter represented in the wider scheme of a decentered subject in an unstable symbolic order. Lacan chose to argue that the letter as a signifier - a piece of paper with words written on it that signified something - always arrived at a destination. Derrida rolled his sparkling eyes and pointed out that his fellow poststructuralist had failed to take notice of the folly of forcing the metaphysics of presence - that the thing, whatever it is, has a center - on a decentered symbolic order. Lacan had apparently leapt to the comfortably centering of presence held dear by some psychoanalytic structures, such as a sensible Ego, and as a result Lacan had not only failed to see the obvious instabilities in the structure of language, he's also failed to embrace the tentative nature inherent in the signifier/signified relationship where there is no metaphysical presence because there is no center to be signified.
In other words for Derrida, the letter, as a vessel of meaning, didn't have to arrive at its destination and indeed the fact that it might not have done, raised a whole new can of meanings which got itself muddled up even more when the great detective August Dupin forged a letter to trap the evil minister of state, save the queen from disgrace and cause maidens throughout the 1840's to break out in hives at the prospect of having to wait 90 years for the vote.