In May 1992, an open letter appeared in The Times, written by eighteen academics from around the world. The academics were writing to protest at the University of Cambridge awarding of an honorary doctorate to the French philosopher Jacques Derrida, famous for works such as Of Grammatology, Writing and Difference, and Speech and Phenomena, and best known for his method, ‘deconstruction’.

According to the letter, Derrida was no philosopher. While his writings ‘do indeed bear some marks of that discipline’ none of them met philosophy's ‘accepted standards of quality and rigour’. In fact, ‘M. Derrida … seems to us to have come close to making a career out of what we regard as translating into the academic sphere tricks and gimmicks similar to those of the Dadaists or the concrete poets.’

While the academics had ‘been willing to give M. Derrida the benefit of the doubt’ enough was enough. ‘Many French philosophers’, they continued, ‘see in M. Derrida only cause for silent embarrassment, his antics having contributed significantly to the widespread impression that contemporary French philosophy is little more than an object of ridicule.’ As David Hugh Mellor, later pro-vice-chancellor of Cambridge, was moved to say at the time, ‘I'm sure Derrida himself doesn't believe most of the nonsense he is famous for.’

What is the ‘nonsense’ Jacques Derrida is famous for? And why did it provoke such hostility? Why does it, almost twenty years after his death, continue to do so, from many in what we might term conventional philosophy? Is it, in fact, philosophy at all?

‘Différance’, ‘phallogocentrism’, ‘deconstruction’ – for many philosophers these new words of Derrida's are as baffling as they are unnecessary. In the letter to The Times, the academics went so far as to call them ‘elaborate jokes and puns’. But to those who followed Derrida, these words have produced a new way of looking at, not just philosophy, but the world itself. And in many ways, they all emerge from the singular character of the thinker himself.

One of Derrida's contested insights is that in order to understand a philosopher, we must look at their life. Traditionally, philosophy has seen itself as above the fray of day-to-day life, making its assessments and judgements from a place somehow free of biographical considerations. This is part of the ‘clarity and rigour’ called for by Derrida's detractors – the personality of the philosopher doesn't matter in the search for ‘Truth’.

Derrida would not argue that the biography of a philosopher completely explains their work, any more than the biography of a novelist completely explains their novels. But in assessing a philosophical position, one must always look at its context. And the life of the philosopher is part of this context.

So, in order to understand Derrida – according to Derrida himself – it is important that we understand who he was, and why he thought the ways he did.

Jacques Derrida was born in Algeria in 1930. If academics wanted to put scare quotes around the word ‘philosopher’ in the phrase ‘French philosopher’ we can also put them around the word ‘French’. The Algeria he was born into was entirely under French rule; he was therefore a French citizen.

What this meant for young Jackie Derrida – named after Jackie Coogan, the then child actor – was that he was brought up speaking French, learning French history and geography in school and eating French food. For the pied noir – shoe-wearing, thus ‘black foot’ – population of Algeria, France itself was home, or as Derrida would call it, the Overthere. This was despite the pied noirs representing only 10 per cent of the Algerian population. The streets on which Derrida played were filled with Arab faces, talking a ‘strange kind of alien language’ he did not understand, which made ‘a hidden frontier, at once invisible and impassable’.

Complicating matters, Derrida was part of the small Jewish population, a minority within a minority. Thus within the ‘privileged’ group, the pied noirs, he was one of the underprivileged. Worse for him, his dark skin meant even fellow Jews mistook him for an Arab. He was, as he said, triply cursed – each category to which he should belong was suspicious of him, and saw him as Other. These complications left him with what he called a ‘disorder of identity’, and a distrust of simple categories.

As we will see, this distrust would have a major effect on his philosophy. All of us as individuals feel to some extent that we don't fit into a simple box, however uncomplicated our origin compared to Derrida's. It was his genius to question the box, rather than the individual, and to see that these boxes, which were not just about identity, but about things like God and truth and gender, were constructions – and therefore could be deconstructed.

What is deconstruction, and how did Derrida come to it? Put simply – a thing which Derrida rarely did for reasons we will come to – anything that is constructed can be deconstructed. This is not, and Derrida was at pains to stress this, destruction. That which is deconstructed is still there afterwards, although hopefully we understand it better.

Anything can be deconstructed – an object such as a text, or a concept such as Truth or God. To take the case of the object that is ‘Jacques Derrida’, we can see how this object has been constructed (by the historical circumstances of his birth, for instance, by the strangeness of his situation). The Jacques Derrida we might meet, or whom we might read about, seems to be a stable character, and yet as we have seen, it is a construction.

As we all are. In writing this piece I am Peter Salmon, the biographer of Jacques Derrida. But I am also many other people, depending on whether I am doing something like this, hanging out with friends, being in love, losing my keys, remembering my past or dreaming about my future. You, as the reader, are as disparate as I am (and as Jacques Derrida is).

As psychology has taught us, one of the hardest pieces of work an individual can do is to take all these disparate selves and make something coherent. And even if we achieve this, a change in circumstances, or mood, or political situation, or relationship, can undo this coherence, and the work begins again (or fails to).

For Derrida, what was important was not the coherent end-product (he didn't in fact believe such coherence was possible) but all the work being done to give the appearance of coherence. Deconstruction is the act of seeking out this work, and what it reveals about the thing. It is also about finding out where the work isn't working – looking, as it were, for the bits of gaffer tape holding the whole thing together, in a text, an individual, a concept.

Derrida called this appearance of coherence ‘the metaphysics of presence’. He argued that philosophy in general has retained an unacknowledged assumption that we ourselves are stable, and the world we describe is as well. We are a consciousness surrounded by objects which we can describe, manipulate and theorize about.

Derrida's fundamental insight was when we explore any object or concept, including ourselves, we find that it is, in fact, unstable. This is not because we do not have enough knowledge, nor because at some point in the future stability can be achieved and we have not got there yet. Rather, it is because instability is ‘always already’ part of anything we choose to analyse – whether it be the self, God or Truth.

Take language. Ideally we would like to fix the meaning of a word – this is something philosophers have tried to do throughout history – Truth means X, the Good means Y. But in our day-to-day experience, words change meaning over time and space. Derrida argues that this is not a defect in language – it is what language is. The German philosopher Friedrich Nietzsche called language ‘a mobile army of metaphors’ – Derrida would concur.

For instance, if we go to a dictionary to get the definition of a word, it takes us to another word and another and another. There is no, as it were, final or original word to which all words refer that allows us out of this chain of signification.

This (missing) final word is what Derrida calls a ‘transcendental signified’. ‘Transcendental’ meaning standing outside of the world, ‘signified’ meaning having a fixed meaning. For Derrida ‘Truth’ and ‘God’ (and ‘Jacques Derrida’) are transcendental signifieds too. They are a creation, a construction, a false coherence. They do not fit within the system that they guarantee – if the final word arrived, language would end, if God arrived religion would end, and if Truth arrived, philosophy would end.

To take another example, this text that you are reading, like any text, gives the appearance of coherence – as though I had the ideas in my head, fully formed, and I sat down and wrote them. In fact there have been many false starts, bits I've written and removed, work done by my editor, terms I was uncertain of that I've cut and pasted from websites and subtly reworded. There are also complicated bits I've left out because I don't want to expose my ignorance. Plus deadlines missed (maybe) and all of the life I've lived between taking the commission and writing the piece. And yet, when I sign my name ‘Peter Salmon’ at the end, it seems to be a totality, just like that – ‘What I reckon about Derrida’.

Any object or concept has this character. Where there is apparent coherence, there is both work and failure – whether it be the self, this text, or Truth. Again, it is important to note that this is not a fault in the system – it is the system, and for some philosophers, such as those who wrote the letter to The Times, this is discomforting to say the least.

This is not to say that Derrida was ‘against Truth’ or was a relativist for whom anything was as true as anything else. Truth, for Derrida, had a number of functions, not the least being that the search for Truth generated philosophy, and therefore a huge, fascinating body of work concerned with what it means to be human, just the concept of God generated all the fascinating narratives of religion.

One does not get rid of Truth, but deconstructs it. Why is this seen as Truth? What is its function here? Who gains and who loses by this construction?

Some of these ideas are not unique to Derrida – the twentieth-century Austrian philosopher Ludwig Wittgenstein wrote that if we wanted to know the meaning of a word (in his example ‘God’) look at how it is used. But Derrida is exemplary on how meticulous he is in adhering to this insight. Those who come to Derrida for the first time (or subsequent times) can find his work incredibly obtuse and frustrating. Why? Because having said that we should be suspicious of fixed meanings, of ‘declarative statements’, he is very careful to avoid them. Unlike many philosophers, who take a moment to point out how strange language is, and how difficult it is to fix definitions, and then go back to what they were saying in more or less the same style, Derrida took this strangeness as unavoidable in his own discourse.

Take ‘différance’, perhaps Derrida's most notorious new word. It is a combination of two words – to differ and to defer. To return to our example of words in the dictionary, any word has two characteristics – it is different from every other word, and its meaning is deferred, it can never be fixed, or we have to wait for the context (such as the rest of the sentence) to understand its meaning. And as with words, so with everything.

This concept emerged from Derrida's work on the philosophy known as phenomenology, in particular the work of Edmund Husserl. Writing in the early twentieth century, Husserl made the daring step of deciding that one of philosophy's most enduring questions, ‘does the world exist?’, was causing too many problems. He proposed that we ‘bracket’ this question – put it to one side – and ask, rather how we experience the world. So, not ‘Does this chair exist?’ but ‘How do I experience this chair?’ Philosophy was the task of describing our experience of the world as human beings; only afterwards should we look for concepts.

Derrida, while being devoted to Husserl – before he was famous Derrida spent nearly fifteen years writing about him – believed that Husserl's philosophy also depended on the ‘metaphysics of presence’. In order to describe the world, one had to imagine a stable self encountering a stable world, and then affixing names to all of it.

Derrida's jumping-off point was Husserl's understanding of time. Husserl had argued that if we are to describe the world we need to find a fixed point in time and space from which to do so – ‘here’ and ‘now’. But in writing about time, Husserl had noted that ‘now’ was an odd construction, containing both the past (which he called ‘retention’) and the future (which he called ‘protention’). His example was musical notes. If we have three of them, and the middle one is ‘now’, what has come before and what follows effect that note – otherwise every C major, whether in a Beethoven symphony or a Kendrick Lamar track, would sound exactly the same. So it is with time. The note is different from other notes, and its meaning is deferred (until we get the next bit). We live our lives in this ‘différance’.

The other thing to note about this word – ‘différance’ – is that ‘a’ in the third syllable, as opposed to the word ‘difference’. Here, perhaps, the Cambridge academics were right – Derrida is being tricksy. He wanted this word to be one that could not be distinguished when spoken, only when written down. Why?

Derrida's early fame rests on his 1967 book Of Grammatology, which many argue is his masterpiece. In it he makes the case that there is another shared assumption among philosophers – that the spoken word is more ‘pure’, more ‘true’ than the written one. Time and again, from Plato to Husserl, philosophers have taken time out from their main argument to rail against the written word. Derrida, as a good post-Freudian, argued that this rage hid some repressed trauma in philosophy's being.

For Derrida, philosophy's devotion to the spoken word is another example of the metaphysics of presence. The model philosophy has aspired to is this: we have a thought in our head, we transfer it into words (which, for some philosophers, including Husserl, was already a contamination), we then speak those words to another human, who takes it into their ear and then has the same thought in their own head.

Writing, however, has been seen as a far more mercurial proposition. As Plato put it, once something is written down, it escapes our protection, wandering ‘fatherless’ in the world. It can be misunderstood more easily, and, he argued, the act of transferring words from speech onto a piece of paper (or papyrus in his case) is a further degradation. Thought, then speech, then writing – each step a degradation of the original meaning, a move away from pure thought.

As we have seen, purity is, for Derrida, a construction. In the case of thought and speech, Derrida argued that philosophers (and theologians, and even common sense) mistook the voice in our heads for our ‘soul’. By his reckoning, the written word bore no more or less correspondence with ‘thoughts in our head’ than the spoken. Do we really think a thought, then speak what we have thought? Try speaking now, try writing now. Generally, the words appear of themselves in some way, and for Derrida, both forms of notation have equal right to call themselves representative of our thinking.

This is important in itself, but it is also an example of another of Derrida's techniques – that of complicating binary oppositions. In this case he has taken the pair speech/writing, with the first term seen as ‘good’, the second as ‘bad’. Derrida does not reverse this, but he explores why the first term is seen as good and the second as bad – for him, both terms are interrelated, and it is a choice to privilege one of them.

The history of philosophy (and culture, and politics, and, well, everything) is full of these binary hierarchies. Good/evil, pure/impure, presence/absence – the first term setting up barriers to not be contaminated by the second. Derrida explores why these barriers have been set up, and what happens when they are.

This becomes a very powerful tool when we come to traditional hierarchies – such as man/woman, white/black, civilized/uncivilized, heterosexual/homosexual. For much of Western thought, Derrida argues, there has been an unspoken assumption that when we call something a normal human, we are assuming a ‘civilized’, white, heterosexual man. There are variations on this, such as ‘woman’, but these at best need to be explained away, at worst seen as a contamination. Sometimes this sexism, for instance, is overt, but Derrida is particularly interested in cases where it is not noticed either by the author or by the reader. (It happens outside books too of course!) This is what Derrida calls phallogocentrism – the man speaks (often about the woman).

It is for this reason that Derrida's work has been particularly influential in fields such as feminism and postcolonialism. To take the latter, when the history of Western thought privileges ‘civilized’, sets its own definitions for what constitutes ‘civilized’, and then feels empowered to define others against that standard, then a large mass of people are going to be defined as lesser – with all the problems such a definition brings (especially for those classed as ‘uncivilized’).

One can see how these questions, asked by Derrida, present a challenge to many of the core beliefs of both culture generally and philosophy particularly. There is something disturbing about being presented with the idea that your search for truth or purity or the good is not only misguided, but may also contribute to the reinforcement of power relationships which you may not wish to reinforce. As mentioned, for many philosophers being ‘above the fray’ is fundamental to their way of going on. To be implicated in the fray is uncomfortable.

Is this why Derrida provokes such savage reactions, such vitriol? He himself saw something primal in the way his work was received by his opponents. After all, deconstruction is, in part, about exposing core beliefs as constructions, and examining who defends them and why. That those who believe in them most strongly are doing the most work to keep them safe is hardly surprising. As he himself put it, ‘If this work seems so threatening, this is because it isn't simply eccentric or strange, but competent, rigorously argued, and carrying conviction.’

Jacques Derrida received his doctorate from Cambridge, 336 votes for, and 204 against, and the walls of the academy failed to crumble.