The cat is crouched low to the ground, whiskers brushing grass. It inches forward in minute movements, eyes drilling towards two sparrows just ahead. It tenses, set to spring. The birds prance like sparring boxers, unaware. But then the cat’s muscles relax. The moment wasn’t quite right – something in the angle or the air. It creeps another inch closer, and another, tautens again, then bursts forwards.

Cats make decisions. And they make decisions about similar kinds of things to us: whom to hang out with and whom to avoid, what to have for dinner tonight and where to get it from. By the standards of most life on Earth, cats have highly sophisticated brains. This gives them a range of behavioural options – a degree of freedom, we might say.

It is often thought that science has shown that there is no such thing as free will. If all things are bound by the same impersonal cosmic laws, then (the story goes) our paths are no freer than those of rocks tumbling down a hill. But this is wrong. Science is giving us a very powerful and clear way to understand freedom of the will. We have just been looking for it in the wrong place. Instead of using an electron microscope or a brain-scanner, we should go to the zoo.

There we will find animals using a wide range of skills that give them options for what to do – skills that we share. These abilities have evolved through natural selection because they are essential for survival: animals need to weigh different factors, explore available options, pursue new alternatives when old strategies don’t work. Together these abilities give all animals, including humans, an entirely natural free will, one that we need precisely because we are not rocks. We are complex organisms actively pursuing our interests in a changing environment.

And we are starting to understand the cognitive abilities that underpin this behavioural freedom. Like most evolved capacities, they are a matter of degree. Take, for example, the ability to delay gratification. For a hungry cat, this means being able to hold back from pouncing until it is sure the sparrow is within range and looking the other way. Experimenters measure this ability by testing how long an animal can resist a small treat in return for a larger reward after a delay. Chickens, for example, can do this for six seconds. They can choose whether to wait for the juicier titbit or not – but only if that titbit comes very soon. A chimpanzee, on the other hand, can wait for a cool two minutes – or even up to eight minutes in some experiments. I am guessing that you could manage a lot longer.

The chimpanzee therefore has more options: if a juicier treat became available after six seconds, a chimp would be free to choose whether to wait for it, but a chicken would not. If you can delay gratification even longer, you have still more options: whether to turn down dessert because you are on a diet, or to forego all pleasure in this world in the hope of a heavenly reward.

As we start to understand, and learn to measure, the capacities that underlie behavioural freedom, we can begin to put this natural free will on a scale. Paralleling the measurement of intelligence, we could call it the freedom quotient: FQ. Such a scale should give us new insights into the factors that hinder or enhance our efforts to shape our lives. In other words, FQ should tell us how free we are – and how we can become even more so.

We desperately need a new way of thinking about free will. The concept lies at the heart of how we see ourselves: assumptions about the extent to which we choose our own fate inform everything from social policy and criminal justice to our personal motivations and sense of life’s meaningfulness. But common conceptions are a muddle, mostly stemming from a pre-scientific age.

One prevalent idea is that freedom requires a supernatural ability to transcend the laws of nature, because otherwise we would appear to be mere puppets of cause and effect. This makes free will into something mysterious, which would set us apart from the rest of creation. As this notion contradicts everything we know about the world, it is no surprise that ever more people are concluding that free will must be an illusion.

Yet all around us, every day, we see a very natural kind of freedom – one that is completely compatible with determinism. It is the kind that living things need to pursue their goals in a world that continually presents them with multiple possibilities. Our intuitive sense that we have free will is based upon this behavioural freedom. And unlike the old mystical idea, this natural ability to shape our future is central to our own wellbeing and that of society. This is what FQ sets out to capture.

A few thinkers have been working towards a naturalistic approach to free will since the 1970s. But in recent years their number has mushroomed – to the point where we might now talk about a small but significant revolution in ideas. There is not yet one single dominant view or definition: different scholars from different traditions tend to emphasise different aspects. But when we join the available dots we get a fairly clear sketch of what FQ might aspire to measure. And it is simply this: the ability to generate options for oneself, to choose, and then to pursue one or more of those options.

Each of these parts is important. First: the capacity to generate options. We are not inclined to ascribe much free will to the creature that sees only one possible course of action, particularly in situations where that course is failing to deliver the goods. That is the kind of behaviour we might associate with an automaton – with the robot whose axles keep turning even though the wheels have fallen off. In 1982 the American cognitive scientist Douglas Hofstadter called such behaviour ‘sphexish’ after the digger wasp Sphex ichneumoneus that allegedly follows very inflexible behavioural routines (and is therefore easily tricked by mean entomologists). It is disputed whether the wasps really are so unbending, but the name has stuck to denote a mechanistic pursuit of a single course of action.

Of course, the number of available options will depend partly upon the circumstances – but also partly on a creature’s creativity and flexibility. In one test to get a treat out of a complex box, for example, chimps tried up to 38 different ways of solving the problem, whereas baboons managed just a handful.

Much of what is required to see decisions through corresponds to processes that we traditionally associate with the will

So we want the ability to generate multiple options. But secondly, we also want to be able to choose between them in a meaningful way. Choosing meaningfully means something like weighing up the pros and cons. If a creature were able to generate six options for itself in any given situation, we might be impressed. But we would be less impressed if it arbitrarily chose which option to take. We would probably conclude that this creature was driven more by randomness than by a genuinely free will. Of course there will be times when we might just as well toss a coin, either because the options are identical (to go foraging in either of two equally laden blackberry bushes) or because we do not have the information to make an informed choice (to explore either of two equally unknown paths in the forest). But most of the time, we want to weigh the options and choose between them in the light of our interests and values (the blackberry bush farthest from the bear’s den).

Thirdly, we want to carry out the choices we have made. Admittedly, much of this depends on things that go on outside of our heads: my decision to eat blackberries could easily be thwarted by finding that they are rotten. But a lot of what is required to see our decisions through also corresponds to processes inside our heads, processes that we traditionally associate with the will. Being free to write an essay, for example, requires that I have the concentration and self-control to stop myself from surfing the web instead.

This three-phased approach is a simplified sketch: the messy reality is that these phases overlap and interact with each other (and with a lot else besides). But it does provide a loose framework within which to consider the kind of underlying capacities that we need in order to exercise natural free will. The first phase, in which we generate options for ourselves, is associated with creativity and innovativeness; perhaps also a kind of openness or intellectual adventurousness. By contrast, the second phase, the ability to weigh options, is what we ordinarily consider to be the capacity to reason. The third phase, pursuing the chosen option, requires different capacities again – mostly what goes under the heading of willpower, such as the ability to delay gratification, which for chickens means up to a six‑second limit and for great apes, including humans, somewhat longer.

If you are able to imagine a number of options for yourself, weigh them with regard to your interests, and then commit yourself to the one that seems the best, you are exercising your free will. Of course, all of these are tasks you might be able to perform better or worse. If you have an abundant imagination, for example, and can think of 20 potential places to forage whereas others can only think of 10, then you have more options and will therefore be freer. If, on the other hand, you are weak-willed, then options that require you to delay gratification – such as walking 10 miles to the juiciest blackberry bush – might be closed, and so you will be less free. These are the variations that an FQ scale should reflect.

At present, we are some way from being able to measure FQ in a generalised sense. Some of the capacities central to this idea of natural free will have established tests, like the American psychologist Walter Mischel’s 1970s ‘marshmallow test’ for self-control (one marshmallow is placed in front of you; if you manage to not eat it for 15 minutes, you get a second one – and are allowed to eat both). But the measurement of, say, creativity remains controversial, although tests do exist (eg, how many uses can you think of for a jellybean?). And once all the component capacities do have reliable tests, there would then come the tricky problem of how to weight them in order to come to an overall score. Is someone who considers few options but is very good at seeing their decision through freer than someone who conjures a host of creative options but is poor at implementing them?

Fortunately, compilers of psychometric tests are used to making such tricky decisions. And it might be that different weightings prove useful for different purposes. In this sense, FQ would be no different from IQ, the intelligence quotient. Like free will, intelligence is a useful but rather fuzzy-edged idea that on closer inspection has many components. IQ tests reflect this: they are composed of sub-tests that measure such different abilities as verbal comprehension, spatial reasoning and working memory. FQ, too, would be a broad summary of a range of component abilities reflecting the different phases of decision-making.

And as with IQ, the usefulness of an FQ scale will depend on whether it correlates with anything else of interest. We would expect someone with, for example, a high IQ to be better at solving difficult engineering problems, learning new languages or constructing complex arguments in law courts. If high IQ did not correlate with these things, we would wonder if it was a meaningful reflection of what we ordinarily consider to be intelligence. Similarly with FQ: we would expect those scoring highly to be good decision-makers, with a strong sense of ownership of their actions and control over their fate; whereas those scoring lowly would be those who see few options for themselves, who feel compelled or addicted, and who are unable to meet their goals or stick to their plans.

Once up and running, we can imagine the kinds of applications and consequences that FQ, as a measure of natural free will, might have. First, we usually hold people accountable for acts that they made freely: if a person lashed out while having an epileptic fit, we would not blame them as we would if they punched someone after cool reflection. But there is no agreed basis for assessing which acts are free. Different countries –­ and even different states within countries – approach this differently, using a muddle of factors from psychology, psychiatry and neuroscience without a coherent framework. At the same time, many are dissuaded from thinking too deeply about underlying causes, because in the old paradigm this implies a determinism that undermines all accountability.

A measure such as FQ could help to bring some clarity to these discussions – though the implications for deciding who should be punished, when and why, are complex. But it is a fair prediction that most current prison inmates have a lower FQ than average (in one New Zealand study, for example, 40 per cent of those with the lowest level of self-control had criminal convictions by the age of 32) – and so in that sense could be considered less accountable. And whether or not prisons are an effective deterrent, it is a reasonable prediction that they are further lowering the inmates’ FQ: making responsible decisions depends on a set of skills, but prisons are (mostly) highly regulated, low-stimulation environments, with few opportunities to develop any such skills. No wonder that reoffending rates are high.

Second, FQ could help us to better understand the complex relationship between free will and social and political freedom. It is clear that states can restrict the freedom of their citizens through laws and other measures. But a state could also limit freedom by hindering the development of FQ, for example, by restricting access to education or brainwashing with propaganda. The long and shameful history of book-banning reflects attempts to diminish a people’s freedom not through chains or walls, but through limiting the options and ideas that occur to them.

it is a good guess that prison populations will have lower than average FQs and that raising FQs would reduce crime

But a person’s FQ will be affected by his environment even without such explicit manipulation. Someone’s sense of whether a wide range of options are available to her will depend upon the attitudes of her parents, teachers and the messages she receives from broader society. Girls in the US, for example, tend to have a lower sense of their competence in maths and sciences than boys, regardless of their actual grades – and consequently fewer girls see careers in these areas as an option. African Americans have a lower sense that their fate is in their own hands than do white Americans – a sense (called locus of control) that is associated with higher academic attainment.

It will always be the case that some people have a freer will than others, and some of that will come down to genes and fortune. But much of that inequality will also stem from systemic advantages and disadvantages: say, the difference between a privileged upbringing with the best education and a community that says everything is possible versus an upbringing that stunts a person’s innate capacities and tells him he is a loser. Some people are lucky, developing the will and opportunities to succeed despite a tough start. But for others, a low FQ will make it difficult for them to improve their lot.

Attempting to smooth out inequalities in FQ – and to raise the FQ of everyone – should therefore be a goal of schools and of social policy. This ties in with the idea of ‘positive liberty’ — the idea that a person should be free, not just from restraints, but through having the skills and opportunities to actively pursue a fulfilling life. Of course, all this assumes that a higher FQ is a thoroughly good thing. But we have good reason to think that this is indeed so, both from society’s point of view, and for each of us individually.

Roy Baumeister, a psychologist at Florida State University and a leading advocate of a naturalised approach to free will, has argued that our capacities for reason, self-control and so forth evolved to enable us to live in complex societies. The notion that we need a significant part of our free will in order to follow rules might at first sound counter-intuitive. But it is actually a familiar idea: we know, for example, that a strong will is required to resist temptation. Often those temptations are to do things that violate social norms, such as coveting your neighbour’s ass or punching him if he covets yours. Hence it is a good guess that prison populations will have lower than average FQs and – equally – that raising FQs would reduce crime.

As well as being broadly socially desirable in the sense that it helps us to manage our behaviour so that we can all get along, a higher FQ should also bring personal benefits. Certainly some of its component elements do correlate with good things. The personality trait known as openness to experience, which includes curiosity and imagination and is therefore crucial to the option-generating phase, has been associated with higher job satisfaction, happiness and quality of life. Or self-control, which is essential to putting one’s choice into effect, correlates with higher educational attainment, more stable relationships and lower frequencies of drug use or criminal conviction.

Once we understand the particular set of capacities that contribute to a free will, we can each individually think about how we might become freer. We can expand our possibilities by learning to be more creative and to explore more options; we can learn techniques that help us to better choose between those options; and we can strengthen the capacities, such as focus and willpower, that allow us to pursue our choices. This might not guarantee happiness and self-fulfillment, but it should make them more likely. Certainly it would put us more in control of our lives: that is, better able to align our everyday actions with our deepest goals and values.

I have claimed that FQ – the freedom quotient – is a measure of our natural freedom of the will. But some people will ask whether these psychological capacities are really free will: for some, a really free will is one that is not determined by anything – one that stands outside the causal chains of nature. Such a person might feel cheated when offered instead a set of capacities that we share (to a degree) with cats and chickens.

We could of course use a different name for what FQ is describing: perhaps ‘psychological freedom’, ‘inner freedom’, ‘autonomy’ or ‘agency’. But I think there are good reasons to stick with the old term. Although there is one strand of thinking in which free will is juxtaposed with determinism, there are also other, more everyday uses that are much less metaphysical. One recent study, for example, found that ‘the folk concept of free will is defined by the capacity to choose based on one’s desires and free from constraints’. Another found that ‘conscious, rational choice and self-control seem to be integral parts of what people perceive as free’.

Even the freest will is still limited, and everyone is ultimately a part of life’s great web of causes and connections

Even when theologians use the term ‘free will’, they are still referring to something very close to what FQ describes. It is with our will, they might say, that we choose to give into temptation or instead to take the path of righteousness. I agree. The difference is that in the Christian tradition, our wills must be absolutely free – not caused by anything such as genes or environment – as only then could it possibly be warranted to send sinners to hell for eternity. With FQ, by contrast, we can recognise that even the freest will is still limited, and that everyone is ultimately a part of life’s great web of causes and connections.

Here again the comparison with intelligence is revealing. For much of the past 2,000 years in the West, intelligence was conceived in terms of a God-given faculty of reason that set humans wholly apart from other creatures. ‘Intellect’ and ‘will’ were seen by the medieval theologian Thomas Aquinas, for example, as the two pre‑eminent faculties of the soul, which did not depend at all on the body.

Now we know differently: we know that we have evolved through a long process of natural selection and that we share our faculties to varying degrees with other animals. Upon realising this, we did not conclude that there wasn’t really any such thing as intelligence – rather, psychologists set about putting it on a scientific footing. Similarly, we should not say that there is no such thing as free will, just because it is not how the theologians imagined; rather, it is time we put it, too, on a scientific footing.