Monthly Archives: January 2013

A field guide to the Higgs

James Ladyman on the discovery at CERN and the rationality of science. This article appears in Issue 59 of The Philosophers’ Magazine. Please support TPM by subscribing.

Atoms turned out not to be atomic because, as we know to our peril, there can be nuclear fission. The triumph of the search for the fundamental building blocks of matter and the discovery of the chemical elements of the Periodic Table was a Pyrrhic victory because, as Henri Poincare said, the atom turned out to be a world in itself. The discovery of the Higgs boson at CERN announced on July 4th means a new particle is added to the bewildering menagerie that already includes quarks, electrons and the W and Z bosons previously discovered at CERN. The latter two particles are bosons, meaning that they obey Bose-Einstein statistics which allow many of them to be in exactly the same state, unlike quarks and electrons which obey the Pauli Exclusion Principle and are known as fermions (obeying Fermi-Dirac statistics). All these particles are fundamental in the sense that they are not composed of other particles.

However, whereas the other fundamental bosons, the W and Z particles and the photon, are all force-carrying particles, the Higgs is not. Rather, it is there to explain why other particles have mass. Electromagnetism holds atoms together by causing the attraction of the positively charged nucleus and the negatively charged electrons. Richard Feynman complained about the lack of an explanation for the mass of the electron, which is very much lighter than the particles that make up the nucleus (nearly 2,000 times lighter than each, and there may be many). If electrons were even a tiny bit more or less massive there would be no stable atoms at all. However, the mystery goes deeper, because in fact the quantum field theory of the electromagnetic and weak interactions that unified them (in a single theory called “electroweak”) calls for electrons to have no mass at all. Meanwhile, it has been found that quarks and W and Z bosons are very massive, while photons are massless. Some mechanism was needed to explain why particles have the masses that they do. This was the problem that Peter Higgs and others proposed to solve by positing a new field and with it new particles.

It is really the Higgs field whose discovery is being celebrated, because particles are not really particles in the everyday sense but rather excitation states of fields. The Higgs boson has no charge, no colour charge (the charge of the strong force that quarks exhibit) and no spin. It does have a mass because the Higgs field interacts with itself, and it is by the mass of the Higgs and the particles into which it decays that it is known. “The” Higgs boson that has been discovered is in fact the lowest excitation state of the Higgs field, which is posited to have a non-zero ground state everywhere to explain the ubiquity of the masses of other particles. While there is only one type of Higgs particle in the Standard Model, there are non-standard models with more, so what has been found is a particle with the mass and properties consistent with a Higgs particle but not necessarily the only one.

Furthermore, while the mystery of how particles can have mass is solved by the Higgs mechanism, and this is confirmed by the discovery at CERN, the current theory of the former gives no explanation for why particles have the particular masses that they do. The electron is simply supposed to interact with the Higgs field via a “coupling constant” whose value is designed to reproduce the known mass of the electron, and likewise for quarks and other particles. So while the discovery of the Higgs is an important result, it is far from the end of the story.

For philosophers the Higgs affair illustrates many issues in the philosophy of science. The theory-ladenness of observation is exemplified by the discovery of a particle that cannot be seen directly – its existence is inferred from the detection of other particles which themselves are known only indirectly. Furthermore, the Higgs particle was not predicted to have its exact mass, rather previous attempts to find it at lower masses all failed, so the theory of the Higgs particle underdetermines this property which is determined from the data. We know from previous experience that our theories and understanding of the Higgs field may be revised, however we can be confident that the Higgs mechanism for symmetry breaking and the structure of the standard model will be retained in future physics at least as an approximation.

Finally this episode in the history of physics demonstrates a fundamental epistemological issue; neither scientific theory nor mathematical statistics can tell us when to stick our necks out and announce a discovery. The convention in this case is when an apparent event has a probability of less than one in about three million of being due to an error. There is no particular reason why this number is chosen instead of one significantly bigger or smaller. As with climate change, experiment and logic and mathematics can only tell us how likely or unlikely our results are given our theory, not how sure we need to be to believe.

James Ladyman is professor of philosophy at the University of Bristol.

The really, really big question

Review by Massimo Pigliucci. This article appears in Issue 59 of The Philosophers’ Magazine. Please support TPM by subscribing.

Why Does the World Exist? An Existential Detective Story by Jim Holt (Liveright), £12.95/$27.95.

“Why is the sky blue?” This perennial question posed by children to their parents can be easily answered by modern moms and dads (after looking it up on Wikipedia): “Because the air scatters short-wavelength radiation better than long-wavelength radiation.” Yes, of course, you then have to explain what “wavelength” and “radiation” are, but it’s a start. No such easy answer is available for the question “Why is there something rather than nothing?” (for which Wikipedia returns a whopping 4,266 entries!). And that is the topic picked by Jim Holt for this lively philosophical-scientific quest concerning the ultimate metaphysical conundrum.

Holt sets up his pursuit as an “existential detective story”, in which his own musings are mixed with the thoughts of a wide range of thinkers, from scientists to philosophers to theologians, several of whom he has interviewed. I was happy to see Holt talk to philosophers who are knowledgeable about the relevant science, as well as to scientists who have at least heard of the word “philosophy”. I happen to think that the confluence of those two disciplines into what used to be called “scientia” (knowledge in the broader sense) is where a lot of the action is these days when it comes to a number of “deep questions”, including consciousness, free will, morality, and the very structure of reality.

I was significantly less happy to have to endure a whole chapter devoted to the musings of Oxford theologian Richard Swinburne, since I think theology fails the test imposed by Hume’s fork (that philosophical assertions need to have either empirical or mathematical content to be taken seriously), and that the best thing to do with it is to “Commit it then to the flames: for it can contain nothing but sophistry and illusion.” I mean, here we are, at the onset of the twenty-first century, and we are still taking seriously people who tell us that God is the simplest “explanation” imaginable for the universe? Could it be that you think so because your imagination is limited, or because you are confused about what counts as an explanation?

But Holt – to his credit – goes to the other extreme as well, also paying a visit to Adolf Grünbaum in Pittsburgh. Grünbaum tells Holt that he is going after a pseudo-question, because nothingness is impossible, which in turn implies that “Why is there something rather than nothing?” is an example of “cadit quaestio”, a fallen question, in response to which it is far better to go out and grab a beer (generally speaking, not a bad suggestion anyway).

Like Holt, however, I don’t share Grünbaum’s slightly too cavalier dismissal of the whole shebang, and think that science and philosophy actually do have a lot to say about it. Which brings the reader to an intellectual tour de force that includes multiverses and the many-worlds interpretation of quantum mechanics (which should really be kept more conceptually distinct than is done in some places in the book), mathematical Platonism, the idea that the universe may be a simulation in someone’s computer (to which Holt gives remarkably little space, particularly compared to Swinburne’s deeply unenlightening musings), and even more bizarre ideas – such as the possibility advanced by Plato that the universe may be the result of an ethical compulsion, or Robert Nozick’s strange “principle of fecundity”.

One idea that I was hoping to see explored was James Ladyman and Don Ross’s suggestion that there is no “ultimate” stuff of which the universe is made, that “at bottom” it’s all about relations (don’t ask “Relations between what?” because you’d be missing the point). While those authors do not explicitly endorse it, a universe in which “every thing must go” (as the title of their book puts it) is also one that is particularly friendly to certain forms of mathematical Platonism, which would have connected quite nicely with Holt’s chapter on Pythagoras, Kurt Gödel, and Roger Penrose.

Regardless, throughout the book the reader will encounter – directly (based on interviews) or indirectly – the thoughts of some of the brightest and most provocative thinkers who have something to say about the deep questions, and two things clearly emerge from the volume. First, the question of why there is something rather than nothing is neither silly nor just of interest to philosophers and “armchair speculators”. Second, like all good philosophy, by the end of the journey the prize is not necessarily getting an answer, but rather consists in gaining a much richer and more nuanced understanding of the question.

Of course, regardless of which take you end up favouring about the origin of all things, you might still come to agree with Douglas Adams: “In the beginning the Universe was created. This has made a lot of people very angry and has been widely regarded as a bad move.” Or maybe not.

Massimo Pigliucci is professor of philosophy at the Graduate Center of the City University of New York. He is the author of the forthcoming Answers for Aristotle: How Science and Philosophy Can Lead Us to A More Meaningful Life (BasicBooks). His philosophical musings can be found www.rationallyspeaking.org.

The best books of 2012

With 2012 safely behind us, we ask TPM’s reviewers to select a favourite book published last year (give or take a few months), taking into account our commitment to the twin virtues of philosophical rigour and readability. As a slightly late stocking stuffer, we offer you this rich, juicy and still mildly festive list of philosophy books which are both illuminating and enjoyable.

Owen Flanagan, The Bodhisattva’s Brain: Buddhism Naturalized, MIT Press.
Most philosophers are bright and well read. A handful has genuine insight. Very few are able to look at an ancient religious tradition and be both scathing about its supernatural excesses and sympathetic to its real wisdom. Hardly any can write clearly, rigorously and with vim and humour. A minority say things of importance to people outside the profession. Take these groups and arrange them in a Venn diagram. Owen Flanagan sits in the very lonely space where they all overlap. – Julian Baggini, founding editor of tpm

Sally Haslanger, Resisting Reality: Social Construction and Social Critique, Oxford University Press.
Haslanger’s volume brings together her influential essays on social reality. Her extremely insightful analysis of social reality (in particular social construction and race and gender) draws on, and is situated within, work in metaphysics, epistemology, and philosophy of language as well as moral and political philosophy. This book shows how abstract philosophical theorising can help us understand better the world we live in. Resisting Reality is engaged philosophy at its best. – Ásta Kristjana Sveinsdóttir, associate professor of philosophy, San Francisco State University

Jim Holt, Why Does the World Exist?: An Existential Detective Story, Liveright.
This book is written mostly as a series of interviews with philosophers, physicists, and theologians, with lots of scene-setting information about Holt’s travels and thoughts between interviews. The story is personal as well as philosophical, especially at the end when he addresses questions of love and death as well as the big metaphysical question that drives the book. Constantly returning to the same issue could seem repetitive, but on the whole Holt avoids this trap, and I can’t imagine a more accessible and likeable introduction to the question of why there is something rather than nothing. – Duncan Richter, professor of philosophy at Virginia Military Institute

Shelley Kagan, Death, Yale University Press.
One of my recent favourites, this book is based on Kagan’s Open Yale Course on the same subject. The book covers a vast range of questions about death, both metaphysical and ethical. How should death best be understood? Should death be feared? Is immortality something to be valued? Would suicide ever be rational? In each case, Kagan’s discussion is both clear and careful, and the book’s conversational style makes it surprisingly easy for readers to plunge into such a heavy topic. – Amy Kind, professor of philosophy at Claremont McKenna College

Jesse Prinz, Beyond Human Nature: How Culture and Experience Shape the Human Mind. W W Norton.
It is over a decade since the Decade of the Brain. The explosion in research over the last twenty-two years may encourage the idea that our physical make-up provides our destiny, unless clever scientists can change it. Prinz’s elegant and far-reaching book brings society back into the picture Though many of its specific conclusions will be familiar to Prinz’s regular readers, the whole picture is an important and refreshing repositioning of community in our understanding of the mind. Prinz’s knowledge of related sciences should be a model for the field. – Anne Jacobson, professor of philosophy at the University of Houston

Alan Ryan, The Making of Modern Liberalism. Princeton University Press.
This collection gathers papers published over four decades, providing a wide-ranging and challenging exploration of the philosophical underpinnings of liberalism. The essays use historical thinkers to illuminate urgent contemporary problems and themes, and Ryan’s investigations of the concept of freedom and of the nature of property rights are fascinating and invigorating. The publication of this book, and of his massive two-volume On Politics (Penguin, 2012) make it evident, indeed undeniable, that Alan Ryan is not only among the most significant political philosophers working today, he is also one of the most exciting. – Troy Jollimore is professor of philosophy at California State University (Chico)

Michael Sandel, What Money Can’t Buy: The Moral Limits of Markets. Penguin.
Sandel’s ability to write in a clear, colloquial, and unpretentious way is impressive. (I am envious.) His target is “market triumphalism”, or “the faith that markets are the primary means for achieving the public good”. He is profoundly sceptical of this particular fundamentalism, as we all have reason to be, thanks to the present economic crisis. Sandel’s piecemeal critique is elegant and incisive. It is timely, and I also like the way Sandel makes his case without lapsing into quasi-Marxian jargon. Expressions such as “surplus value” and “exploitation of the proletariat” never appear in the text. – Alan Haworth, Human Rights and Social Justice Research Institute, London Metropolitan University

Helen Steward, A Metaphysics for Freedom, Oxford University Press.
Steward introduces a novel position in the free-will debate – agency-incompatibilism. In the free will literature, compatibilists and incompatibilists (i.e., those who take free agency to be compatible with determinism and those who do not) have assumed that it would be possible for there to be agents in a deterministic world and focused their debate on whether agents in such a world would act freely. Steward thinks that this is a mistake. Agency itself, she argues, is incompatible with determinism. Not only has Steward introduced a novel view into a debate that stretches back thousands of years (no mean feat), she has made a compelling case for this view. Moreover, she argues persuasively that human and non-human animals are agents, creatures capable of settling for themselves what they shall do. Anyone interested in mind and agency must read this book. – Clayton Littlejohn, lecturer in philosophy at King’s College, London

Bruce N Waller, Against Moral Responsibility, MIT Press.
Waller challenges a dogma of contemporary philosophy – the near consensus that we possess free will just insofar as we possess the capacity to act with moral responsibility. Waller takes an unusual position in arguing that we possess a form of compatibilist free will, while at the same time denying that we are ever morally responsible for our actions. Whether or not the argument is ultimately persuasive, the author develops it with much detail, care, and attention to empirical data. – Russell Blackford, author of Freedom of Religion and the Secular State, Wiley-Blackwell

Jonathan Wolff, Ethics and Public Policy: A Philosophical Inquiry, Routledge.
This is a first-class examination of where philosophy meets public policy by one of the leading political philosophers today. Wolff illuminates the enormous potential for philosophical engagement with social and political issues in an accessible and even inspiring account. – Thom Brooks, reader in law & affiliate member of philosophy department, Durham University