The meaning of ‘meaning’ is more complicated. Words and sentences have meaning, as do lives. Is it the same kind of thing in both cases? In one sense, the ‘meaning’ of ‘life’ could be a simple dictionary definition, something like the one I gave in the previous paragraph. But that’s not what people want when they ask about the meaning of life, any more than it would help someone who was suffering from an identity crisis to read the name on their driver’s licence. One important difference between linguistic meaning and what I’ll call the meaningfulness of a human life is that the second seems to entail a value judgment, or a cluster of them, which in turn implies a certain kind of emotion. Your mathematics homework is full of meaning in the sense that it consists entirely of a network of concepts — meanings, in other words. But in most cases there is not much emotion linked to doing sums, and so people tend not to regard it as very meaningful in the sense in which we are interested. (In fact, some people loathe doing mathematics, or have anxiety about it, but those reactions hardly seem conducive to viewing the subject as a source of meaning in life.)

Questions about life’s meaning are really about meaningfulness. We don’t simply want to know the dictionary definition of our lives, if they have such a thing. We want our lives to have value, to fit into some kind of intelligible context. Yet these existential concerns do seem to touch on the merely linguistic sense of the word ‘meaning’ because they invoke understanding and mental associations. It is remarkable how many synonyms for meaningfulness also refer to merely verbal content: we talk, for instance, about the point of life, or its significance, or whether or not it makes sense. If we want to understand the meaning of life, it seems as though we need to grapple with the nature of meaning in this less exalted sense.

Life goals come from three sources, so in a sense every human life has three basic sources of purpose. One is nature. It built you for a particular purpose, which is to sustain life by surviving and reproducing. Nature doesn’t care whether you’re happy, much as people wish to be happy. We are descended from people who were good at reproducing and at surviving long enough to do so. Nature’s purpose for you is not all-encompassing. It doesn’t care what you do on a Sunday afternoon as long as you manage to survive and, sooner or later, reproduce.

The second source of purpose is culture. Culture tells you what is valuable and important. Some cultures tell you exactly what you are supposed to do: they mark you out for a particular slot (farmer, soldier, mother etc). Others offer a much wider range of options and put less pressure on you to adopt a particular one, though they certainly reward some choices more than others.

That brings us to the third source of goals: your own choices. In modern Western countries in particular, society presents you with a broad range of paths and you decide which one to take. For whatever reason — inclination, talent, inertia, high pay, good benefits — you choose one set of goals for yourself (your occupation, for example). You create the meaning of your life, fleshing out the sketch that nature and culture provided. You can even choose to defy it: many people choose not to reproduce, and some even choose not to survive. Many others resist and rebel at what their culture has chosen for them.

People ask what is the meaning of life, as if there is a single answer

The second need for meaning is value. This means having a basis for knowing what is right and wrong, good and bad. ‘Good’ and ‘bad’ are among the first words children learn. They are some of the earliest and most culturally universal concepts, and among the few words that house pets sometimes acquire. In terms of brain reactions, the feeling that something is good or bad comes very fast, almost immediately after you recognise what it is. Solitary creatures judge good and bad by how they feel upon encountering something (does it reward them or punish them?). Humans, as social beings, can understand good and bad in loftier ways, such as their moral quality.

In practice, when it comes to making life meaningful, people need to find values that cast their lives in positive ways, justifying who they are and what they do. Justification is ultimately subject to social, consensual judgment, so one needs to have explanations that will satisfy other people in the society (especially the people who enforce the laws). Again, nature makes some values, and culture adds a truckload of additional ones. It’s not clear whether people can invent their own values, but some do originate from inside the self and become elaborated. People have strong inner desires that shape their reactions.

The third need is for efficacy. It’s not very satisfying to have goals and values if you can’t do anything about them. People like to feel that they can make a difference. Their values have to find expression in their life and work. Or, to look at it the other way around, people have to be able steer events towards positive outcomes (by their lights) and away from negative ones.

The last need is for self-worth. People with meaningful lives typically have some basis for thinking that they are good people, maybe even a little better than certain other people. At a minimum, people want to believe that they are better than they might have been had they chosen or behaved or performed badly. They have earned some degree of respect.

The meaningful life, then, has four properties. It has purposes that guide actions from present and past into the future, lending it direction. It has values that enable us to judge what is good and bad; and, in particular, that allow us to justify our actions and strivings as good. It is marked by efficacy, in which our actions make a positive contribution towards realising our goals and values. And it provides a basis for regarding ourselves in a positive light, as good and worthy people.

People ask what is the meaning of life, as if there is a single answer. There is no one answer: there are thousands of different ones. A life will be meaningful if it finds responses to the four questions of purpose, value, efficacy, and self-worth. It is these questions, not the answers, that endure and unify.