I found the authors’ approach too leisurely. I sometimes felt that I didn’t need the periph-erals, I just wanted to get the points morequickly, with simpler arguments. Even so, I learned many new things from this book. So my advice to the reader is: be patient and enjoy this deeply scientific and superblyartistic book. ■

Masatoshi Nei is at the Institute of MolecularEvolutionary Genetics, Pennsylvania StateUniversity, University Park, Pennsylvania 16802, USA.

Winning the fightagainst liver diseaseHepatitis B: The Hunt for a Killer Virusby Baruch S. BlumbergPrinceton University Press: 2002. 272 pp.$27.95, £19.95

Arie J. Zuckerman

Hepatitis B is a common viral infection of theliver and a major global public-health prob-lem. More than 2 billion people alive today— over a third of the world’s population —have been infected with the hepatitis B virus,and of these about 350 million will becomecarriers of the virus. Some 20–25% of carriers will progress to serious liver disease,including chronic active hepatitis, cirrhosisand primary liver cancer. Primary liver cancer is the seventh most common cancerin males and the ninth most common infemales, and the hepatitis B virus is secondonly to tobacco among the known humancarcinogens. Although the precise molecularmechanisms by which the virus inducesmalignancy remain largely unknown, it isthe cause of 80% of the world’s primary liver cancer, which is one of the three mostcommon causes of cancer deaths in males ineast and Southeast Asia, the Pacific Basin andsub-Saharan Africa.

The discovery by Baruch Blumberg of the Australia antigen, a specific viral markerof the hepatitis B virus, was one of the mostimportant advances in medical knowledgeduring the past 50 years and had huge implications for preventive medicine. Thisinspiring book is an intensely personal andinteresting account of the work of Blumbergand his close associates who, after discov-ering the Australia antigen, continued towork on hepatitis B and devised the first-generation vaccine for this infection.

Because of this personal focus, there isrelatively little mention of the contributionsmade by many researchers across the worldand the crucial role of the World HealthOrganization in the unfolding story of thefive different types of viral hepatitis and theimplementation of universal immunization

against hepatitis B in over 100 countries.Rates of liver cancer have fallen significantlyin regions that have immunization pro-grammes, such as Taiwan. If immunizationis introduced universally, the hepatitis Bvirus could be eradicated within 20–50 years.

Blumberg was born in Brooklyn, NewYork, and attended a yeshiva, the intellectualpowerhouse of traditional Jewish education.He continued his education at Far RockawaySchool in New York, a public high school that counts three Nobel laureates, includingBlumberg, among its alumni. He read medicine at Columbia University College of Physicians and Surgeons before leavingNew York to read biochemistry at BalliolCollege, Oxford, UK.

The discovery of the Australia antigen wasbased on Blumberg’s interest in genetic vari-ation and specific susceptibility to disease,and his use of the Ouchterlony double-geldiffusion test to detect antigen–antibodyinteractions by the formation of precipitinlines in a gel. Blumberg did not set out to finda marker for hepatitis B — his interest was ininherited polymorphic traits. He conducteda systematic search of sera from multiplytransfused patients to find antisera thatcould detect new antigenic polymorphismsamong low-density lipoproteins and otherproteins. He also used sera obtained fromAustralian Aborigines as part of a collab-orative study.

The antibody used to find the antigen was serum obtained from New York patientswith haemophilia, who had received manytransfusions (and thus almost inevitablycontracted hepatitis B). The rest, of course, ishistory, and is narrated in an eloquent andengaging style. The paper on the associationbetween the Australia antigen and hepatitiswas initially rejected by the Annals of InternalMedicine in 1967 because the reviewer wasreluctant to risk another false claim for the identification of the elusive hepatitisvirus(es). But it was published in the end,and Blumberg received the Nobel prize inPhysiology or Medicine in 1976.

The book is a gem, though it is a pityabout the title, which was borrowed from anoverworked newspaper headline. It is essen-tial reading for all aspiring scientists, the faceless bureaucrats who control the budgetsfor medical research, and devotees of theResearch Assessment Exercise (it is doubtfulif Blumberg’s work would have attained a sig-nificant score). And it should be read by thethousands of people who work on the controland eradication of the hepatitis B virus. ■

Arie J. Zuckerman is director of the World HealthOrganization Collaborating Centre for Referenceand Research on Viral Diseases, Royal Free andUniversity College Medical School, Rowland HillStreet, London NW3 2PF, UK.

A philosophicalliberatorInvariances: The Structure of theObjective Worldby Robert NozickHarvard University Press: 2001. 432 pp. $35, £23.95, 40.30 euros

Hans-Johann Glock

Philosophers generally have one of three distinct attitudes towards natural science.Some, like Blaise Pascal and Martin Heidegger, hold science in contempt, on thegrounds that philosophy, religion and thearts provide superior insights into the natureof the world and the human condition. Others, such as Bertrand Russell, WillardVan Orman Quine and most contemporaryanalytic philosophers, take their lead fromthe results and methods of science, and tend to regard philosophy as a part of, or atleast continuous with, science. Philosophersof a third type also treat science with greatrespect but insist that philosophy is qualita-tively distinct from science, because it is asecond-order discipline that, rather thandescribing reality, reflects on the conceptsused, for example, in scientific descriptions

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Looking back: Baruch Blumberg’s research on hepatitis B drew on earlier fieldwork in Suriname.

© 2002 Nature Publishing Group

of reality. Following Immanuel Kant, thisstance can be labelled ‘critical’, because itallows philosophy to question scientistsabout anything that is conceptually unclearand about inconsistencies that might marthe expression of their factual discoveries.

The Harvard philosopher Robert Nozickis very much of the second, scientific variety.Although Invariances stops short of dissolv-ing philosophy into science, it seeks to trans-form philosophical problems into empirical,factual ones. Its topic, the structure of theobjective world, is clearly scientific, but thefocus is distinctively philosophical. Nozick isless interested in exploring specific objectivephenomena than in the question of whatconstitutes objectivity. His answer, in a nut-shell, is that a phenomenon is objective to the extent to which it is invariant under a range of possible transformations.

At the same time, he deplores the typicalphilosophical stance according to whichmany statements are necessary and invariantacross all possible worlds. “Too often,philosophers insist that things must be a certain way, and they make it their businessto close off possibilities,” writes Nozick. Bycontrast, he seeks to open up surprising new conceptual possibilities.

The purpose of his ‘philosophical forays’is to challenge presumed necessities, andthereby our intuitions and our received con-ceptual framework, by invoking unheard-of possibilities raised by modern science. This challenge includes statements such as:“Water is H2O”. Saul Kripke and Hilary Putnam have argued that the term ‘water’does not refer to a substance with certainperceptible properties (such as being acolourless and odourless liquid). Rather,they say it refers in any possible world to the

substance that has the same microstructureas the stuff we call water in the actual world.Empirical scientific investigation is neededto establish what that structure is. However,in any possible world, only that which is H2Ocan be water, so it is a metaphysical necessitythat water is H2O. Nozick disputes this celebrated reasoning. If there is a possibleworld in which H2O is a green and smellysubstance, that substance must be water. Butthis is not an intrinsic necessity about thatworld, it is ‘imported’ from the fact that inour actual world we use ‘water’ to refer to allsubstances with a certain microstructure.

Nozick is commendably undogmatic inhis discussions of dissenting positions, andhis policy of conceptual laissez-faire isundoubtedly attractive. But it brings with itthe danger of the kind of conceptual confu-sions and unacknowledged terminologicalshifts that the critical tradition warnedagainst. It goes without saying that scientistsand scientifically minded philosophers haveevery right to introduce new conceptualinstruments to explain new empirical find-ings. But if we are to understand these instruments properly, then we must clarifytheir connection to established (scientific or ordinary) concepts. Nozick seems to thinkthat such explanation is unnecessary, andthat new terminology can never be faulted as long as it is interesting.

But his own explorations do not alwaysbear out this confidence. Science can haveundesirable philosophical admirers — people who appeal to scientific findings and theories in an irresponsible and uncon-trolled way. An example of this is the 1996‘Sokal hoax’, in which the physicist AlanSokal wrote a spoof article riddled with scientific nonsense and persuaded a leading

cultural-studies journal to publish it.Nobody could accuse Nozick of the kind of ignorance and fraudulence betokened bysome postmodernist thinkers — his discus-sions are exceedingly well-informed, intelli-gent and illuminating. As a guide to how scientific findings impinge on philosophicalorthodoxies in various fields. the book ishighly recommended. However, it often sacrifices clarity and argumentative rigour inits quest for suggestive link-ups with science.

This is evident in Nozick’s uncriticalacceptance of ‘evolutionary cosmology’, thehighly speculative and extremely metaphor-ical application of genetic and evolutionaryterms to whole universes, and his discussionof truth and relativism. Nozick does recog-nize that his laissez-faire attitude is close to postmodern relativism, and he attemptsto show that relativism is not just coherentbut partly true. But his defence is flawed:postmodernists cannot avoid local chargesof inconsistency by abandoning all of ourreceived concepts and theories at once, asthis will simply leave them without anythingintelligible to say.

Furthermore, Nozick invokes quantummechanics and special relativity to establishthat truth is relative to both time and place (a statement is not absolutely true, but onlyfor a certain time and in a certain place).Quantum mechanics shows that whether anevent occurs at a certain time is not fixed anddetermined absolutely. However, there is adifference between being true and beingcausally determined. It is true that event eoccurred at time t if, and only if, event eoccurred at time t, irrespective of whether e was predetermined at an earlier time ormeasurable at a later time. Nozick simplywants us to ignore this point and to assimilate being true with what he calls ‘determinately holding’. But this revision leads him to reject the most basic conceptual truth about truth:that it is true that p if, and only if, p. Anyonewho rejects this equivalence is simply nolonger talking about truth. (Indeed, Nozickhimself relies on this equivalence when hepoints out that “it is true that p” does notmean the same as “it is believed that p”).

Finally, Nozick demands far too muchfrom an ‘illuminating’ theory of truth,because he confuses the question “What istruth?” with the question “What is true?”.Answering the latter requires a scientific solution to the riddles of the universe, whereas answering the former requires ‘only’an analysis of the concept of truth as used by scientists and laypeople. The role of conceptual policeman is less attractive thanthe role of conceptual liberator that Nozickoccupies to such striking effect. But both arerequired if philosophy and science are to benefit from one another. ■

Hans-Johann Glock is in the Department ofPhilosophy, University of Reading, Reading RG6 6AA, UK.

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Wax models of embryos and other biologicalspecimens were widely used by anatomists inthe latter half of the nineteenth century.Researchers produced their own three-dimensionalmodels to help them understand thestructures they observed, andcommercially prepared models werewidely used in teaching. Some of the finestand most widely used wax models, such asthat of a human embryo in several pieces shownhere, were produced by Adolf Ziegler, who trained as a doctor of medicine, and his son Friedrich. The Zieglers acted as ‘wax publishers’ for scientists such asAlexander Ecker, Ernst Haeckel and Wilhelm His.The history of the Ziegler models and theirimpact on embryological research is told in the lavishly illustrated book Embryos in Wax: Models from the Ziegler Studio by NickHopwood (Whipple Museum of the History ofSciences, University of Cambridge, and the Instituteof the History of Medicine, University of Bern, £15).

Medical models

© 2002 Nature Publishing Group