There is philosophy within each of us.

‘No, that's not me at all. I'm not philosophical.’

Actually, I'll bet that you are more philosophical than you realize. Do you think of yourself as lacking time or aptitude for philosophy? Have you ever really tried it? Have you ever taken it seriously?

‘No, I've always had so much else to do. And no one encouraged me to think about philosophy.’

Well, I'm encouraging you, right now.

‘Thanks. Okay, you say that I already have some philosophy within me. Why wouldn't I have noticed it? Surely it's impossible to have it without noticing it.’

No, it is possible. Even if you aren't conscious of an inner philosophy, it could be there, a part of you. Maybe others notice it, when watching how you behave: you might unwittingly be enacting a philosophy, displaying it in how you act, in how you carry yourself. Words are not always needed for this; you could be wordlessly living a philosophy. For example, perhaps you react sympathetically, respectfully, and generously to everyone, including people with a lower socioeconomic standing than your own. You might never notice this about yourself; you do it automatically. Even so, you would be living an acceptance of a form of egalitarianism – a thesis often discussed within political or social philosophy.

Of course, it is one thing to have a philosophy. It is another thing to have or live a good philosophy – one of which to be proud, with which you are content to be identified publicly. Is your philosophy already as good as it could be? As it should be? Those questions arise equally about a lived philosophy: what if you are only egalitarian in your actions within your own country, not when visiting elsewhere? Those are blunt questions, but we may react optimistically, seeing within them the invigorating idea of finding and then improving your philosophy. Nor does the optimism stop there: to improve your philosophy is to improve your self, particularly if your philosophy is located so deeply within you as to be animating and guiding your actions.

This book embraces that general theme, with a specific focus. We will be doing epistemology, a pivotal part of philosophy. Epistemology asks about the nature and value of knowledge – your knowledge, anyone's knowledge. And yes, you already have some epistemology within you. Believe me, you do. (Even being able and willing to think about this idea could mark you as somewhat epistemological.) Maybe yours is still a fledgling epistemology – fragmentary, incomplete, under­developed. It probably needs further work before it is polished, purposeful, powerful. How should you begin that work? How should you pursue it?

Here is how you can start: read this book, critically and questioningly. You will be reflecting deliberately and overtly upon philosophical ideas about knowledge. This will give you a better sense of what to look for in an epistemology. Otherwise, you might not understand even what thoughts within you, and what actions you perform, amount to an epistemology at all. You could be looking within yourself without adequate guidance. You might flounder. You might waste time and energy. You might lose motivation.

This book can fix all of that. It can help you to appreciate what an epistemology is. Feel encouraged to find your own epistemology. Then challenge yourself to enrich it. In that way, this is a self-help book. After reading the book, you will have more – and improved – epistemology within you. You will have thought further about what knowledge is and why it matters. You will have reflected upon this vital aspect of yourself.

Here is an analogy. It is likely that everyone has within them some moral philosophy, such as views about what makes an action or a person morally good or bad. But maybe not everyone has an impressive moral philosophy. As social media make abundantly clear, day after day, so many people have much to say about what is moral, and what is not. With unending energy, they express opinions on what is right and what is wrong – yet usually without depth and consistency, subtlety or complexity, in their moral stances. This could be improved by those people reflecting more philosophically upon morality – consciously noticing, modifying, and extending their own moral ideas, first of all. It is possible to become a better thinker, a more sage adviser, about moral matters.

And what is possible in that way for ideas about morality is also possible for ideas about knowing. This book is here to help you to sharpen and deepen your thinking about knowledge – what it is, what is involved in having it. This can be intellectually and personally demanding. Luckily, it is also fun.

Pascal Porcheron at Polity invited me to write this book. I welcomed the chance to do so. I enjoy the challenge of conveying complex philosophical ideas simply. (So I have minimized references, throughout the body of the book, to specific authors. Such details appear in the ‘Further Reading’ section.) Pascal gave me some very useful editorial advice, as did two anonymous referees. I am also grateful to Parveen Seehra for her helpful questions and comments on a draft of the book, and to Lindsay Yeates for his expertise regarding one of my examples.