Can brain science tell us how to live?

Dominic Murphy, The University of Sydney

Paul Thagard The Brain and the Meaning of Life, Princeton NJ, Princeton University Press, 2012 (296 pp). ISBN 9-78069115-440-4 (paperback) RRP $34.95.

A common complaint about philosophy is that it has lost touch with its historical mission of telling us how to live. That does sound like one job for philosophy, although philosophers have always gone in for other tasks as well. Many of these, especially since the 17th century, have concerned philosophy’s relation to science. The early modern period marks the moment when philosophers who are interested in finding the intellectual action begin turning from theology and towards the study of the natural world.

Can philosophy put the science and the guidance together, and show what the science means for how one ought to live? Descartes thought that philosophy could train your mind, and that discipline would improve your life, but what if science itself, directly, could tell you how to live, and answer the big questions?

Paul Thagard’s new book, The Brain and the Meaning of Life, is billed as an attempt to use science to answer the big questions, but in fact it is even more ambitious than its title suggests, for much of the book is concerned with epistemology and practical reasoning, not just morality and metaphysics. Thagard thinks that changing one’s mind in a rational fashion involves inference to the best explanation, and that deciding what to do involves inference to the best plan. What should guide your plans? The satisfaction of your needs, which boils down to love, work and play, which together make up the meaning of life.

Thagard has published a string of distinguished books and papers on reasoning and scientific explanation, and was a pioneer in using cognitive science to study the way scientists think. The sections on reasoning bear the imprint of this work, and pack a lot of philosophy into a short span. The idea that you should change your mind based on the best explanation, for example, amounts to a rejection of the authority of logic over thought. Logic states rules that show us when a sentence (the conclusion) has to be true if you assume that previous sentences (the premises) are true. These rules don’t just give you a good reason to accept the conclusion if you accept the premises, but a reason that cannot rationally be doubted. This suggests a model of thought: start by trying to find true premises, and then reason logically so that you are guaranteed to reach true conclusions. This picture has been accepted by many great philosophers. It is still accepted by those who cling to the idea that the laws of logic are the laws of thought, which rational people should use as a guide to thinking correctly.

Thagard’s rival approach is fully in the modern naturalistic mainstream, which takes science as the exemplar of reliable knowledge-gathering. Logic, on this view, is the science of valid argument, and not a guide to how you should think. This marks a break with the mainstream of Western philosophy since classical antiquity, which stressed the need for certain foundations for knowledge, the sort of thing which, like the conclusion to a mathematical proof, could not be doubted. In place of this commitment to certainty, Thagard offers inference to the best explanation. This style is seen in medical diagnosis—as Thagard discusses in his excellent little book How Scientist Explain Disease (1999)—and also, as he notes, is famously exemplified by The Origin of Species, which offers up a huge array of facts about the nature and distribution of organisms, and argues that the hypothesis of descent with modification can explain them better than anything else.

Even gay marriage activists often draw the line at polygamy.

But suppose you want to know why we should trust what science claims? The search for certain foundations took this worry very seriously. The modern naturalistic philosopher does not; the deliverances of science are legitimised, on this account, by science itself. It is the best way of gaining knowledge available to us, according to the standards we have adopted, which are those of science. The circularity here is patent, and naturalistic philosophers (I am one) have learned to live with it. I think science is epistemically superior, but cannot be shown to be so in a way that will defeat a sceptic. Thagard, though, wants to defeat a particular kind of sceptic; viz. a religious believer. A believer is likely to have firm views about how to think about the big questions, for religion supplies rival answers to the questions Thagard asks.

Thagard has to take religion on because it’s the competing franchise when it comes to the meaning of life, so its entitlement to answer the big questions needs to be invalidated. But if science does not rest on certain, or even non-circular, foundations, how is that to be done? Thagard urges the superiority of evidence over faith. You want your doctor to make up her mind based on the collection of evidence and inference to the likeliest explanation for it, so why would you rest your thoughts about even more important matters than your health on faith rather than evidence? I can’t see this persuading a religious person. For one thing, faith might not work in medicine but might work in metaphysics; for another, religious people might just disagree about what counts as evidence. Holy Writ might not seem like evidence to Thagard, but that’s because he takes the arbiter of what counts as evidence to be science rather than religion. And the right of science to epistemic dominance is just what’s at stake.

If you’re already inclined to put your trust in scientific standards of reasoning and evidence, though, Thagard is likely to be both persuasive and eye-opening. The book doesn’t just suggest that science beats religion when it comes to the nature of reality, it also makes the case that science teaches us how to learn and how to act. Whether or not you ultimately buy the conclusions, it is a real service to put the cognitive and social science of decision making into the public sphere so crisply.

Thagard begins his answer to the big questions by following Albert Camus, in The Myth of Sisyphus, who asked, why don’t you kill yourself? Why keep going at all? At the end of Chekhov’s Uncle Vanya Sonia tries to comfort the despondent Voitski with the consolations of faith: ‘We shall rest. We shall hear the angels. We shall see heaven shining like a jewel. We shall see all evil and all our pain sink away in the great compassion that shall enfold the world’. You might keep going because you have a hope that at the end of it all things will get better.

Except it won’t. There is not much consolation to be looked forward to if the modern scientific consensus is to be believed. There are no angels awaiting us, and no God to wipe away our tears. You might fear that if science has shown us that there is no God, then we are all the product of a blind historical, wasteful process that means nothing, for there is no purpose in nature that we are working out. There is no afterlife, no point to it all. Why refrain from killing yourself, since nothing you work for has any significance? You will die, your children will die, and none of it will have had any meaning.

You don’t have to draw on science to hold that life is misery and pointlessness. Philosophy alone can lead you to it: the 19th century German philosopher Arthur Schopenhauer, who made Woody Allen look like an optimist, argued for it on metaphysical grounds, and drew on eastern religious traditions as well. The contemporary South African philosopher David Benatar recently suggested that we would all be better off if we had never been born. Bringing someone into existence, thinks Benatar, is a great harm. But thinkers steeped in modern science have drawn or predicted some conclusions that are pretty grim for many things that a lot of people value. If we are just animals, descended with modifications from primeval slime, then what happens to right and wrong, and freedom of the will, and what is there to replace that long-treasured but scientifically suspect entity, your immortal soul?

What is the scientific argument for the moral authority of science?

The striking thing about The Brain and the Meaning of Life is how optimistic it is; even, at times, complacent. Thagard thinks that immortality and freewill will have to go, but despite all this unsettling science nothing of any value will be lost. Neuroscience doesn’t overturn our conception of ourselves, it just deepens our understanding of ourselves by revealing the neural underpinnings of what we always thought was important. Thagard offers us an account which is wide-ranging, thoughtful and stimulating. The result, however, is a view of the world and the place of humanity within it that is perfectly suited to justify the beliefs and values of a secular, educated, western liberal. I am a secular, educated, western liberal, and I share the values Thagard avows, but even I think this is a bit too neat. I do not think it likely that the scientifically correct answer to the big questions is that my friends and I have been right all along. Indeed, Thagard gets himself into a little bit of bother when his arguments just seem too concerned to shore up the liberal consensus. For example, he thinks that because objective human rights can be founded on the needs of human beings, we can endorse moral reforms that further those needs while violating nobody’s rights. That means that obviously homosexuality is fine. Ah, but then what about polygamy? Even gay marriage activists often draw the line at polygamy, and Thagard shares their qualms. As matter of consistency, it would seem to follow from his views about rights: provided women enter polygamous relationships freely, it seems that nobody’s rights are being violated. Well, says Thagard, polygamy has historically been associated with the oppression of women. This is true, but historically every form of family life has been associated with the oppression of women, so there is no reason to single out polygamy. If tradition is to be abandoned for what science tells you, then it should be abandoned, not modified where it makes you queasy and adopted elsewhere.

So let’s look at the big picture from which this moral outlook derives. At the centre of a meaningful life, says Thagard, are love, work and play: love includes all manner of deep human attachment, not just romance or childrearing; work exercises important capacities and brings monetary and other rewards; play includes whatever you do for entertainment and relaxation, whether it is watching undemanding television or struggling to learn the oboe. A full life that centres on love, work and play will involve goals. You want that big promotion, or to make new friends when you move to a new town, and these goals can be met or not. If they are not met, you should consider revising them. Perhaps your goals should be more modest—really, you are too short and too old to make a career in basketball now, but you can aspire to senior management—or you should sacrifice some goals. The big promotion may exceed what you can expect at this stage of your career, or perhaps you will find it unattainable if at the same time you give your family the attention you think they deserve. Something will have to give, and your goals for either love or work will need to be revised. On the whole, you want a life that balances, or at least contains elements of, all three. People have basic needs for competence, autonomy and relatedness, and the triumvirate of love, work and play helps to satisfy them.

There is no freewill or immortality, because science tells us that there is no part of you that has the properties of the traditional soul. No intellect survives death and transcends material causes to control your behaviour. But that doesn’t mean that you are a robot. You are fully material, and your mental life depends on a brain functioning in a social environment, but you can still be sensitive to reasons and exercise deliberate self-control. And there is no divine lawgiver, but there can still be objective morality. Science tells us that people have vital biological needs, which can serve as the basis for objective human rights, which in turn can ground a pluralistic consequentialism. Actions should be judged by their consequences, but there are lots of consequences that should be taken into account. People need food and water, but they also need respect, freedom, equality and security.

Morality also has to be grounded in science, because Thagard insists that any component of your view of the world should be rejected if it is not supported by science, even if it matters to you and makes you happy. You should interrogate your beliefs on the big questions and throw out the ones that cannot be supported, because to live otherwise is to live a lie. This is the assumption lying behind Thagard’s dethronement of religion, and it is never argued for. It is essentially a moral claim itself and not one supported by science. What is the scientific argument for the moral authority of science?

Nor does the truth cheer you up. (I mean, look how depressing the facts are.) Religious people are more likely to report being happy, and epistemic scruples do not do a lot for your well-being. But a commitment to the truth is at the heart of Thagard’s picture of the good life, and really should have been brought out alongside love, work and play. Unlike them, there seems to be little evidence that a commitment to the truth will meet a basic human need, but it is a crucial part of the package of values he pushes. It really justifies the reliance on science, but has no foundation in science. (Indeed, the relation of truth to science is unclear, if only because many important scientific claims are idealisations and hence strictly speaking not true at all.)

A commitment to the truth is at the heart of Thagard’s picture of the good life.

So Thagard’s big picture is attractive to those of who share his commitments. You should love, work and play, stop pining for the metaphysically impossible, follow the truth and treat people with respect. The relationship between his big picture and science, though, is more complex than he asserts. From the fact that humans have basic needs discoverable from science it does not follow that we should satisfy them, for what if the basic needs turn out to include things a bit less attractive, like the power to push other people around? There are a lot of hierarchies in primate society, and people at the top of human hierarchies are better off than their subordinates on a number of measures. In Leviathan Thomas Hobbes described laughter as ‘sudden glory’. It sounds wonderful, until you realise what he means, which is that laughter reflects a sudden realisation that you are more eminent than someone else. So maybe science tells us that alongside love, work, play and truth we should also install dominion over others. I suspect that Thagard would baulk at this, as he does with polygamy. The real moral of the book, I think, is that the modern liberal, secular consensus is not threatened by science, and may even be supported by it. But that doesn’t show that it derives from those values. We may discover darker basic needs that are not even consistent with those values, let alone part of them, and the fact that they are on the same scientific footing as the attractive values should not sway us away from trying to be nice to people.

The other strange aspect of the book’s relation to science is how little the basic picture has to do with neuroscience, despite constant talk of the brain. The science Thagard draws on is really psychology, in two senses. Much of the evidence he assembles to bolster his picture is actually behavioural data from behavioural research that has nothing to do with neuroscience. But even the more directly brain-based components of his scientific repertoire are driven by psychology. Thagard draws at several points on his EMOCON model of emotion, which outlines the brain areas involved in the processing of emotion. But all the explanations we get of what the brain areas do are psychological, in the sense that Thagard tells us which parts of the emotional process are realised in what parts of the brain. The description of the process itself is entirely couched in familiar psychological language. The neuroscience tells you where things happen, but it is the psychology that lets us know what is going on.

This is entirely characteristic of most modern cognitive neuroscience. If you go to a neuroscience conference you can attend lots of sessions where cellular mechanisms are investigated using a conceptual repertoire that uses concepts that have emerged from the experiments themselves. If you attend a session on cognition you find that the concepts being used are typically ones generated in a psychology lab, or just inherited from our wider cultural tradition.

This is starting to change as the neuroscientists begin to ask questions about phenomena that are distinctly their own and remote from traditional psychology (what is the job of the brain’s default network? What does the dopamine spike represent?) but Thagard’s picture is one in which neuroscience does not upend any of our familiar psychology of needs, values, beliefs and desires.

So why all the stress on the brain? Talk about the brain seems more scientific than talk about the psych lab and materialism seems like a big new deal. But materialism is an old idea, and on any plausible account of the scientific method, psychology has just as much of it as does neuroscience. In a lot of modern science writing, neuroscience just seems to be playing the role of reassuring you that this is proper science we’re talking about, while at the same time reassuring you that our traditional understanding of human nature is still intact.

I don’t think things will carry on like this. Maturing sciences typically transform our commonsense conceptual structures, and we should expect neuroscience to do the same, ultimately making the truth about human nature as remote from ordinary people as most other scientific truth. As we learn more about the brain, the old psychological verities will probably fade away to be replaced by a new scientific vocabulary that will take decades or centuries for us to come to turns with. But telling people to honour love, work and play will probably still be good advice.


Benatar, D. 2006, Better Never To Have Been: The Harm of Coming into Existence, Oxford University Press, Oxford.

Camus, A. 1991, The Myth of Sisyphus and Other Essays, English edn, Vintage, London.

Chekhov, A. 2008 (1897), Uncle Vanya, trans. Project Gutenberg [Online]: Available: [2012, Nov 1].

Hobbes, T. 1996, Leviathan, Revised student edition, ed. R. Tuck, Cambridge University Press, Cambridge.

Schopenhauer, A. 1966 (1818/1844) The World as Will and Representation, trans. E.J.F. Payne, Dover Publications, New York.

Thagard, P. 1999, How Scientists Explain Disease, Princeton University Press, Princeton.

Associate Professor Dominic Murphy is director of the Unit for History and Philosophy of Science at The University of Sydney. He is the author of Psychiatry in the Scientific Image (MIT Press 2006) and many articles and book chapters on obscure topics in the philosophy of the biological and cognitive sciences.