Master of the New College of the Humanities in London, Professor AC Grayling is a philosopher who has written and edited more than 30 books, including The Age of Genius (Bloomsbury, 2016) and Democracy and its Crisis (Oneworld, 2017). He has also written columns for The Guardian and The Times


Ellie Cawthorne: Your book covers more than two millennia of philosophical thought. What are the biggest conundrums that philosophers have had to grapple with in that time?

AC Grayling: You can ultimately reduce philosophy down to two great questions: what is reality, and what is of value in the world? These two questions have driven the whole history of thought. From the very beginning of western philosophy, before Plato even, people were contemplating the nature of reality and of value, just as they are in philosophy today.

Now, these two questions are obviously too big to be answered just by themselves, so you have to break them down. And it’s in that breaking down that you get to the more particular questions, such as: what is knowledge and how do you get it? What is truth? What is the best way to reason? What’s right, what’s wrong, and what’s the best kind of life to lead?

How have the interests of philosophers changed over time? Medieval thinkers had very different concerns to those of the Enlightenment, for example…

As well as the set of perennial questions that every generation must ask and answer for itself, as debate has gone on, the field of philosophy has accumulated more insights, more perspectives and more theories. And it has generated ways of thinking that have allowed their own disciplines to break away and become independent. For example, in the 16th and 17th centuries, questions about the nature of reality gave rise to natural science, the study of the physical world. Philosophical enquiries gave rise to psychology in the 18th century; sociology and empirical linguistics in the 19th century; and cognitive science and artificial intelligence in the 20th century.

You have to remember that every new discovery or advancement we make opens up new horizons of enquiry. And so it might be that in 50, 100 or 500 years’ time, philosophers will be asking themselves questions about things that we can’t even imagine yet.

How have emerging ideas shaped the course of historical events?

History moves on wheels of ideas, and ideas are the remit of philosophy. So you could argue that the great driver of historical change has always been the debates that we have: about how we should organise society, who should be in power, and what’s right or good. These are all philosophical questions. Accordingly, philosophy has been a central influence in the development of almost every advance and change that we can think of in history.

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For a specific example, just think of Karl Marx sitting thinking in the reading room of the British Library. Within half a century his ideas had convulsed the world in revolution and utterly changed the face of global history.

Go back a bit further to the end of the 17th century, when the English philosopher John Locke famously wrote his two treatises of government, the second of which lays out the justification for what we call the Glorious Revolution of 1688. That document was quoted verbatim in the documents of the American and French revolutions. It had a powerful impact on the way the founders of the United States thought about how they should set up their new society. Those are just two examples of philosophical ideas changing the course of history, but I could cite many more.

In order to understand any historical period or epoch, we’ve got to ask ourselves, what were people thinking at the time – and why? What was the dominant ideology? Why did people accept certain ideas and reject others? When you do that you see some interesting contrasts. Think, for example, of the difference between the Middle Ages and the Renaissance. Look at the art of the high medieval period – full of resurrections, annunciations, crucifixions, flagellations. Then compare that to the art of the Renaissance – picnics in the countryside, landscapes, portraits, nudes. That’s a very different artistic ethos. What had changed? All of this was triggered by a fundamental shift in ways of thinking. In the high medieval period, life was insecure, people believed themselves to be in a vale of tears, struggling to escape the dangers of sin so that they could make it into the bliss of an afterlife. But by the Renaissance, people were concentrating on the value of life in the here and now – there was a new recognition of the fact that experience and natural beauty can give us great satisfaction in the present.

To flip that last question on its head, how have great thinkers been shaped by the times they were writing in?

I don’t think we can divorce any philosophical text from the historical context it was created in. Think, for example, of the horrors and atrocities of the Second World War. That catastrophe generated a whole new burst of philosophical reflection. In its aftermath, many thinkers, such as Hannah Arendt, set about trying to make sense of how it is that we human beings – as inherently social animals that need to love and be loved – could have turned on each other like that. There was an effort to make sense of the bad as well as the good, to try to learn from the mistakes that had been made.

After surveying so many influential thinkers in your book, what do you think makes a truly great philosopher?

Depth of insight, originality, and having an effect on the way that subsequent generations of people think about things. A philosophical mind is one that belongs to a childish heart – always curious, always open, and always vitally interested in trying to make sense of things. The beautiful thing about philosophy is that it’s a licence to be interested in everything, but it’s a duty to be interested in everything too.

Almost everybody is a philosopher, I can prove this easily: anybody who goes to the pub will know that as the evening goes on, you get smarter and more deep-thinking. We all like to discuss great questions. And it’s important that we do. I think that the quest for explanations, understanding and insight is natural to us as human beings.

Whose work do you think towers above the rest?

Of the really great western philosophers, three stand out: Plato, Aristotle and Immanuel Kant. These three figures have gone so much deeper into the problems that philosophy throws up, and have provided ways of thinking that have changed the nature of the conversation after their time. That is what I think singles them out as truly great.

[The 20th-century philosopher] Alfred North Whitehead said that “all philosophy is footnotes to Plato”, and that isn’t too gross an exaggeration. If you look at Plato’s work, you see that he identified the real problems and touched on almost every major topic in philosophy.

Now Aristotle; what a great genius Aristotle was, the most extraordinary mind. His interests ranged right across what we would call science, politics, ethics and the deepest questions about the very nature of existence. Aristotle almost single-handedly created the science of logic. Although we have a large number of his works, most of those that he actually wrote for publication have now been lost. His dialogues, none of which survive, were described as literary masterpieces even greater than those written by Plato, his teacher – and Plato’s dialogues are among the great treasures of world literature.

Like Aristotle before him, Kant [1724–1804] had a universal mind. He lectured on all sorts of things including astronomy, mathematics and military fortifications. When he was in his late 40s, he finally settled down and devoted himself to his great philosophical works.

Kant was writing at a point in history where two major philosophical traditions, empiricism [the belief that the origin of knowledge lies in sensory experience] and rationalism [which argues that reason is the path to knowledge], had gelled into alternative ways of thinking about understanding. But in the Critique of Pure Reason, he found a way of showing how elements of both traditions are important for making sense of how we see the world.

Ideas live on far beyond the thinker who conceived them. How have concepts been reimagined or misinterpreted over time?

Nietzsche provides a prime example of this. After he died, his sister, who was very conservative and rather reactionary, used bits of his writings to make him appear like some sort of forerunner of Nazism. Nietzsche was actually very hostile to anti-Semitism and nationalism, so he was anything but a Nazi. But, as Cardinal Richelieu once said:

“Give me six lines that anybody has written and I can use them to have that man hanged.” This is exactly what happened here – Nietzsche’s views were distorted to present him in a quite different light to one that he would have agreed with.

Plato, Aristotle and Kant are the three greatest western philosophers. They changed the nature of the conversation after their time

The thing to remember is that the history of philosophy is the history of a conversation. We who study philosophy now are constantly in dialogue with our forebears, and that conversation always involves interpretation and reinterpretation. When we look at philosophers of the past, we have to try and reconstruct what it is that they were striving for.

Let me give you an example. The person regarded as the first philosopher was a man called Thales, who lived in the early sixth century BC. He said that everything has a soul. He referred to a magnet which could draw bits of iron to itself, which he took to mean that it must have a little soul in it. Now, he didn’t literally mean a soul as we might imagine it – with little feathery wings on. What he meant was a power and an ability to act upon other things. But he didn’t have the vocabulary or the conceptual scheme available to express that, as he was the first person trying to articulate this idea. So in order to make sense of Thales' views, you have to look into what it was he was trying to express and not just how he was expressing it. This is especially tricky with ancient philosophers, as a huge amount of the culture of classical antiquity has been lost or destroyed, and so much of what they wrote or said comes to us only in bits and pieces.

What do you think makes a particular idea catch fire?

Ideas take root if they really touch a nerve, and hit on an intellectual and an emotional need in us that has to be satisfied. Sometimes brilliant ideas have to wait for their time, like a seed in the ground, before they can really shoot up. But, at other times, ways of thinking can become so entrenched in societies that they start to ossify. Philosophy should always challenge our assumptions, otherwise we end up getting stuck in old habits and ways of thinking which can be bad for us, both individually and as a society.

Ideas find their time when they offer something fresh, and help us to see things that we didn’t see before.

Book: The History of Philosophy by AC Grayling (Viking, 704 pages, £26)


This article was first published in the July 2019 edition of BBC History Magazine