Introduction

Some years ago, I wrote a review of the excellent book Thinking, Fast and Slow by Daniel Kahneman, the renowned psychologist and winner of the Nobel Prize in Economics (there is no prize for psychology).1 As the title suggests, the book is about how human thought operates via two systems: a fast one, which is intuitive and usually quite effective, but also has an inbuilt tendency to make mistakes; and a slow one that is more mentally demanding but often more reliable. In my review, I cited one of Kahneman's well-known examples, which I have reproduced below. When you read it, try to blurt out your answer to the simple sum automatically - and then wait for a minute or two before working it out systematically.

A bat and ball cost $1.10.
The bat costs one dollar more than the ball.
How much does the ball cost?

Easy enough, you might think. Most people's quick-fire intuitive answer is 10 cents. Indeed, that may be how it looks at first glance, but think a little deeper and longer and you'll realise it's wrong. If the ball costs 10 cents and the bat costs a dollar more than the ball, the bat must cost $1.10, which takes the total cost above the amount stipulated in the original premise. The correct answer must be that the ball costs 5 cents (and the bat $1.05). Elementary arithmetic, perhaps, but not immediately obvious to the fast thinker - even for gifted adults like you, the reader. As the example shows, following your intuition or gut feeling isn't always the best way to go. For some questions and problems, it's better to slow down. The first thing that springs to mind isn't always right, no matter how many people claim otherwise, including the authors of self-help books and management manuals.

I cite this example not just because it is an exemplary illustration of one of the kinds of cognitive errors that Kahneman has spent a long career studying, but also because, after reading my review, an angry woman - a complete stranger - called me about it. She sounded rational enough and wanted to take me to task for what she considered a self-evident mistake. It was clear to all and sundry that the ball cost 10 cents! She sounded almost embarrassed on my behalf because I didn't get it. I tried to be patient and talk her through the sum, but she stood firm. (I may have written a book about standing firm, but this wasn't really what I had in mind!)

My critic passionately explained why I was wrong. Getting me to think straight obviously meant a great deal to her. My failure (in her eyes) to grasp the problem bothered her, and she wanted to help. Her concern echoed Kahneman's desire to help his readers think better and train them to minimise cognitive errors. For most of us, it's important not only that we and our fellow human beings behave properly - comply with certain moral virtues - but also that we think properly and, in doing so, comply with certain intellectual virtues. It's important not only to act well but also to think well. Doing so puts us in touch with reality, which helps us learn. It also encourages us to think critically, which allows us to identify those aspects of the world in need of improvement. Good, deep thinking can also be - in my opinion - a source of true joy. Especially when we think for ourselves. The ancient Greek philosophers lauded the joy of thinking, of thoughtfulness, of the contemplative life, and considered it the highest human calling. That is what this book is all about - advocating a thoughtful life.

The difference between Kahneman and the woman on the phone, of course, is that one is right and the other wrong. There is only one correct answer to a sum. All others are wrong. This underlines the fundamental normativity of thinking: that there are more or less correct ways to deploy our capacity to think. There are, quite simply, norms for good and valid thinking, and we would do well to learn them. One theme of this book is that learning to think is part of the process known as formation (Bildung, as the Germans call it) - learning to be a fully rounded thinking person - which is described in detail later in the book. Thinking is fundamental to living a good life.

To the best of our knowledge, humans are the only creatures on the planet capable of thinking in the true sense of the word. All sorts of animals intuitively calculate risk (a hyena tempted to steal from a lion weighs up the risk of finding themselves on the menu), but only humans make actual calculations, because only we have access to the world of numbers and mathematical symbols. Humans are also the only creatures capable of thinking about the meaning of life, the nature of a just society or the potential existence of a deity. We can do these things because we possess the ability to think reflectively - to think about how we think - and because we have language, which the philosopher Ludwig Wittgenstein called 'the vehicle of thought'.2 We need language and its concepts in order to think about the past, the future, good, evil, or other abstract matters, including thinking itself.

However, even though thinking is normative - that is, it can be right and wrong - and even though some of its norms appear objective (those of logic, for example), it's still important that we learn to think for ourselves. The rounded individual understands the history and communities of which they are a part, and can think independently. They have developed their own voice, which makes them capable of forming their own opinions about issues and questions, but when doing so they always take into account other people and the world around them. Indeed, this is the basic idea of humanism: that you must learn to think for yourself. To think well. To use your reason. And to resist anything that threatens your ability to do so. But how do we manage that as products of our circumstances? How can we think slowly, deeply and in a rounded manner in a world driven by utility value, power and haste? These are the type of questions addressed in this book. I will argue that thinking, in the true sense of the word, is one of the most important things you can do in life - and one of the most human things, too. However, I will also assert that the nature of our modern world is not conducive to thoughtfulness, and that this means there is every reason for us to re-learn how to think well and deeply.

Why practise something you already know how to do?

We live in strange times. Although most of us are perfectly capable of using our legs to go for a walk, books about how to walk and hike are published all the time. The majority of us manage to fall asleep most nights, yet a torrent of literature is churned out about how to sleep better. And even though many people know what it feels like to fall into a reverie and just be there in the moment, bookshop shelves are bulging with guides to meditation and mindfulness, which treat the phenomenon as a technique to be taught. Humans really are uniquely capable of making their own bodies and minds the object of training, discipline and improvement. We are, as the German philosopher Peter Sloterdijk puts it, creatures condemned to practise even the most simple and uncomplicated of things.

It is easy to marvel and poke fun at this 'technification' of the simple - I should know, and readily admit that I have been guilty of doing just that. Nevertheless, I intend to stick my neck out in this book and add yet another area to the list of phenomena that we all already know about and yet, I maintain, a lot of us would do well to practise: thinking.

But what is thinking? It is clearly more than just solving mathematical problems, as in Kahneman's example. Can we arrive at a tentative understanding of the phenomenon even at this early stage in the book?

Before I introduce definitions and theories about thinking, let me hark back to some of the most delightful moments I can remember, moments that revolved around precisely that - thinking. As a child, I would spend hours lying on the carpet, basking in the spring sun as it flooded in through our big living room windows, just letting my mind wander. In my head, I told myself stories and dreamt of being an explorer. Sometimes, an atlas would help kickstart my imagination. This was thinking as joyful daydreaming. In the winter, this form of reverie would take place in front of the wood-burning stove, and it's surely no coincidence that I often fell into thought as the sun or the wood burner warmed my body. Often, my thinking was accompanied by distinct physical sensations. For example, I would feel a bit faint or empty when I pondered whether the universe is infinite. Neither finiteness nor infinity is comprehensible, yet the question is worth thinking about. As I walked the few miles to school, I often conducted long conversations with myself which - unlike my physical being - had no particular destination. It was probably the very absence of ulterior goals that made the thinking so edifying. It was thinking just for the sake of thinking. I also remember the embarrassment of occasionally being caught talking to myself as I ambled along, lost in thought. These days, I know there was nothing to be ashamed of - I was just deeply immersed in my thoughts.

As an adult, I find it more difficult to lose myself in thought like that, but it still happens sometimes when I'm out for a run or a bike ride. Often, it results in...