Innovation is the key to understanding both Oren Harman and Michael R. Dietrich's most recent volume and its precursor Rebels, Mavericks, and Heretics in Biology (2008). What distinguishes the two is that, while the innovative ideas discussed in the latter came from scientists whose disciplinary backgrounds were directly linked to their areas of research, in Outsider Scientists we are instead required to focus on those boundary-crossers who were not trained in the areas of biology that they came to practise in. Aside from this important and enlightening shift in focus, the formats of the books are the same, in that they both consist of a series of biographical essays. Harman and Dietrich begin with an introductory chapter that establishes the thesis as they see it (which I will turn to shortly). Eighteen chapters follow, each on particular researchers and their travels into more or less unfamiliar territory. They cover, in turn, Gregor Mendel, Louis Pasteur, Félix d'Herelle, Samuel Butler, Erwin Schrödinger, Linus Pauling, Walter Goad, R.A. Fisher, Nicolas Rashevsky, Robert MacArthur, Noam Chomsky, Elaine Morgan, David Hull, Ilya Metchnikoff, François Jacob, John von Neumann and Norbert Wiener, George Price, and finally Drew Endy. The volume is then completed by an epilogue authored by Richard Lewontin. While the extent to which these biographies support or advance Harman and Dietrich's argument will be the focus of this review, it should be stated that each chapter is punchy, well balanced (for readers unfamiliar with any of the figures listed above), and eminently readable – this book has wider audiences in view than merely history and philosophy of science (HPS).

Harman and Dietrich's central thesis, despite taking on such an ostensibly broad topic as ‘outsider science’, ends up being really quite specific. Any number of things might be considered sufficient to raise a person's status to that of outsider – gender, social or economic status, nationality, disability, sexuality, language, religion, and so on – each of which, it might then be argued, contributed to how and why they saw an area of science with fresh eyes and produced exceptionally novel solutions. These are not Harman and Dietrich's outsiders. Disciplinary affiliation or previous scientific training (training not shared by the majority of biologists working in the research area to be intruded upon) are the essential features distinguishing outsiders from insiders. The editors are sure to caution against seeing too much stability in ‘disciplines', stressing the fluidity of disciplinary boundaries within and without biology. Instead they emphasize the movement of individuals between distinct communities or working traditions (there is a passing reference to Jonathan Harwood's version of ‘styles of thought’, which I found particularly instructive for understanding the nature of the inside/outside distinction that the authors wish to make). Having fleshed out this idea, and some of the ways that they hope a focus on outsider science will be productive, the editors hand over the reins to their numerous contributors. As with any project of this size, the transition is not entirely seamless, and a few gaps appear. These problems are not, however, fatal to Harman and Dietrich's thesis, which could simply do with further exploration and clarification – at least more than can be achieved in a single edited collection, especially one built upon the expertise of such a large number of different authors.

With this very brief distillation of the book's aims in mind, three problems within the contributions are worth flagging. First, more than one author seeks to diminish or even eliminate their historical actor's status as an ‘outsider’. This is helpful inasmuch as it reminds the reader that the category of ‘outsider’ is a problematic one, but as far as advancing the argument that scientists with non-biological training have contributed to biological science, one cannot help but wonder why all were included. This problem is almost wholly confined to the chapters on Mendel, Pasteur and Schrödinger (the first two of which are discussed under the section ‘Outsiders before the inside’, which, though playful, also invites confusion). Second, a more pervasive problem throughout all chapters is an overemphasis on the innovative ideas themselves. This comes at the expense of concretely demonstrating that these innovations were the result of previous non-biological training – rather than some other influence – or explaining why certain innovations were adopted by biologists and others virtually ignored. Those chapters dealing with outsiders who innovated but failed to have their ideas taken up within biology do not give a symmetrical explanation as to why; the most common explanation is some form of personality clash. Third, and finally, the motivations of outsider scientists for approaching biology in the first place do not enter into Harman and Dietrich's broad programme, which instead focuses on the processes of transition from one field to another, dependent – as they see it – upon personalities, patrons, institutions and so on. While Harman and Dietrich warn against seeing their outsiders as ‘lone knowers', the ultimate effect of focusing on individual characters is inevitably that the heroic qualities of boundary-crossers are emphasized in ways that might not be to the tastes of an HPS audience (though once again, this is not the only audience that Harman and Dietrich are catering for). Not enough consideration of what was ‘in it’ for outsiders means that the obvious answer – further evidencing of their expertise or further evidencing of, or legitimacy bestowed upon, the original insight or method inspired by science elsewhere – is overlooked. To repeat: these problems are far from fatal for the Harman and Dietrich thesis, which merely requires more dedicated elaboration in order to ensure that it explains as broad a spectrum of outsider cases and phenomena as possible.

Having dealt with these problems, it is much more important to emphasize all the new avenues for research that Harman and Dietrich have opened up before us, and which are now ripe for exploration. Two are particularly attractive. First, for instance, in virtually every chapter, industry or war provide important patronage, or contexts of incentive, for the work of the outsiders discussed. This therefore places these scientists – the majority working within the twentieth century – directly within the purview of some of our most successful and comprehensive accounts of science in this period (while partially addressing the problem of motivation highlighted above). Does this also thereby tell us something distinctive about the relationship between outsiders and industrial/military problems? Second, the importance of the social perception of outsider scientists – both within different scientific communities and within society more generally – is another common feature of all of these biographies. If being an ‘outsider’ has such important social implications, might we have a further distinct phenomenon worthy of analysis? Could we soon be reading articles moving beyond the ‘Matthew effect’ to consider the ‘Marvin effect’, the greater public attention, scholarly scrutiny, perhaps also (in some cases) scientific value, given to work originating in alien hands? All this is to say that Harman and Dietrich have introduced a provocative concept, and corralled a rich body of work that brings it to life. Knowing now that outsiders exist, you might start to see them everywhere.