* This is the latest installment of “Problematica.” It is written by Max Dresow…
Extinct styles itself the “philosophy of palaeontology blog.” But I have a confession to make. I’m hesitant to call myself a “philosopher of paleontology” (with or without the second “a”). Sure, there are philosophical issues in paleontology, some of them deep. But how many of these are distinctively paleontological issues? I’m happy to grant that there’s a philosophy of the historical sciences worthy of the name— but philosophy of paleontology? I’m not convinced.
Perhaps the first person to be called a philosopher of paleontology was William Whewell (1794–1866): the only philosopher to serve as president of the Geological Society of London. Among his many gifts, Whewell was the most talented and prolific scientific wordsmith of his day. It is to him that we owe such familiar terms as “electrode,” “ion,” “cathode,” “anode,” “astigmatism,” “physicist,” and, yes, even “scientist.” He also suggested names for no fewer than three geological epochs (Pliocene, Miocene, and Eocene); adapted the French words “carnivore” and “insectivore”; burdened scholars with “uniformitarianism” and “catastrophism”; and redeemed himself with the lovely “consilience.” But since wordsmithing is a difficult game, he also produced a few duds. One of these is “palaetiology” (pronounced pale-eat-ee-ology): Whewell's term for historical science. You see, Whewell never actually called himself a philosopher of paleontology. His claim was to have described the foundations of a relatively new department of the natural sciences: the palaetiological sciences. That is the subject of this essay.
For Whewell, a science counts as palaetiological when its object is “to ascend from the present state of things to a more ancient condition, from which the present is derived by intelligible causes.” Examples include geology, paleontology, glossology (an early term for “linguistics”—another Whewellian coinage), and comparative archaeology. Any of these might equally have served as a model for palaetiological science. Yet in expounding his ideas on the subject, Whewell talks almost exclusively about geology. In this respect, geology might be called the paradigmatic palaetiological science, since it supplied for Whewell an especially clear model, or exemplification, of the general type.
Whewell's decision to focus on geology was not idiosyncratic. To a degree that is hard to appreciate today, geology was the “it” science of the early Victorian era. Gentleman, fashionable ladies, country parsons, and even some university men found it irresistible, as much for its supposed moral benefits as for its intrinsic interest. Here, for example, is Robert Bakewell, expounding these benefits in his Introduction to Geology (1815):
It may be advanced as an additional recommendation to the study of geology, that it leads its votaries to explore alpine districts, where the surrounding scenery and the salubrity of the air conspire to invigorate the health, and give to the mind a certain degree of elasticity and freshness, which will enable them on their return to discharge with greater alacrity the duties of active and social life. (Bakewell 1815, 25)
Likewise, William Fitton, an early Fellow of the Geological Society of London, wrote that “Geology has this great advantage, of which not even Botany partakes more largely, that it leads continually to healthful and active exertion, amid the grandest and most animating scenery of Nature” (Fitton 1817, 74). We are inclined to smile at remarks like this, but in the world of nineteenth century Britain, the benefits of good air and healthful exertion were not to be gainsaid.
Yet for all its charms, geology did not much resemble the paradigmatic “mature” science of the period, Newtonian mechanics. How then was its scientific status to be understood? Whewell set out to answer this question. The challenge was far from trivial. As Jon Hodge observes, when Whewell began his History of the Inductive Sciences, there “was no consensus concerning geology as a site on the map of knowledge or as a division in the classification of the sciences” (Hodge 1991). Even within Whewell’s own philosophy, geology’s standing as an “inductive science” was none too clear. Here is the issue. For Whewell, every inductive science has one or more “Fundamental Ideas” particular to itself. So, the idea of Cause belongs to the science of mechanics, and the idea of Space to geometry. But geology has no Fundamental Idea of its own: only a variant of the idea that Whewell arrogates to mechanics (Cause). This is the idea of a “historical cause,” by which Whewell means a cause that “occupies some certain portion of time [but not another]” (Whewell 1837, 112).*
[* Non-historical causes, by contrast, operate “at all times and under all circumstances.”]
The importance of this situation is made clear by some observations that Whewell recorded in his notebook in 1831. Here Whewell distinguishes between what he terms “permanent causes,” or causes of things continuing as they are, and “progressive causes,” or causes of things coming to be. Permanent causes include the force of gravitation and the luminiferous ether. They are the “non-historical [or mechanical] causes” of the History. Progressive causes, by contrast, include the true account of the origin of the Alps (whatever that is) and Laplace’s nebular theory (assuming it is correct). These are the historical causes. Whewell racks his brain but can think of no reason to regard permanent causes as better candidates for scientific investigation than progressive ones, despite the latter's sporadic operation. Still, it remains the case that sciences of progressive causation, like geology, “[differ] somewhat from the sciences so called” (Hodge 1991, 266). This is because the main business of science is to determine laws that are “universally and constantly true”; but geology seeks mainly to ascertain particular things that happened at particular times in the past. If geology is a science, then, it is an unusual one, whose aim is not to arrive at universal laws, but rather to frame a true account of the origin of some part of the earth.
If Whewell had ever considered excluding geology from the inductive sciences, this doubt is no longer evident the History. Still, his discussion of geology comes at the very end of his historical survey, in part to signal that geology “differs somewhat from the sciences so called,” and in part to suggest that geology supplies portal connecting science and natural theology (more on this later). Geology belongs to the inductive sciences because it is based on the idea of causation, and so conforms to the picture of induction that looks to ideas to colligate the facts of experience (in this case, traces of the past). Yet it differs from sciences like physics in that it is based on an idea of causation that orients it towards particular chains of events rather than universal relations. The term “palaetiological science” serves to mark this distinction, and to highlight the status of geology as a separate-but-perhaps-not-quite-equal partner among the inductive sciences.
* * *
While the palaetiological sciences differ from the other inductive sciences in lacking a Fundamental Idea, they resemble them in other respects. For example, in both cases, there is a descriptive or phenomenological portion (think Kepler), and a dynamical or causal one (think Newton). The phenomenological portion involves the classification of phenomena according to “the true principles of natural classes,” as well as the formulation of laws concerning such things as “[the] general form of mountain chains; the relations of the direction and inclination of different chains to each other; the general features of mineral veins, faults, and fissures; [and] the prevalent characters of slaty cleavage” (Whewell 1840, 104). This sets the stage for “aetiological” research, whose aim is to formulate the laws responsible for the “facts” recorded in the phenomenological department. In the science Whewell terms “Geological Dynamics,” for instance, researchers treat “not only [the] subterraneous forces by which parts of the earth’s crust are shaken, elevated, or ruptured, but also [the] causes which may change the climate of a portion of the earth’s surface… [and those] which modify the forms and habits of animals and vegetables” (102). But Geological Dynamics is not an end in itself—it is rather a kind of intermediary between Phenomenal and Physical Geology, or true geological theory. Unsurprisingly, given that geology in the 1830s remained a young science, Whewell did not think that any “such theory [yet] exist[ed] on any [geological] subject" (122).
The absence was to some extent a product of design. The Geological Society of London was born under the seal of a performative hyper-empiricism (Rudwick 1985). Geologists were not to engage in speculative theorizing in the tradition of James Hutton (the Scottish intellectual who had yet to achieve his status as an icon of positive science). Instead, they were to behave as fact-gatherers and reporters soberly committed to a basically descriptive task. This bit of ideology held sway for the first few decades of the nineteenth century, at least in Britain. But by the 1830s, overt geological theorizing had quietly re-emerged from the stifling restrictions placed upon it by the earlier generation. In 1834, a Fellow with a French name even had the temerity to release a book titled Researches in Theoretical Geology.* This book was in large measure a reaction to a book published several years before: Charles Lyell's Principles of Geology, whose first two volumes appeared in 1830 and 1833.
[* The Fellow was Henry De la Beche, first director of the Geological Survey of Great Britain and, despite his name, an Englishman. (“De la Beche” is a stylized version of his family name, Beach, which also gives the key to its pronunciation [Day-la-Beach]. He is the bespectacled man in the illustration below.)]
Principles of Geology was, in Lyell's telling, an attempt to establish principles of right reasoning in geological science. These principles were basically Newtonian, and functioned as a kind of dampener on the (often overheated) geological imagination. The book was not a treatise on geological reasoning, however. Many of the 1,300 pages in the complete first edition were devoted to a comprehensive review of known geological agencies. Then there was a sustained argument against Lamarckian transformism, which provided a coordinating theme for Volume 2. Finally, Volume 3 was devoted to a review of the youngest geological strata, which Lyell turned into an argument against the notion that a sharp discontinuity separates the present world from the past. And all in service of a grand theoretical idea, that Earth has long existed in a kind of steady state; or as the cosmopolitan Lyell might have put it, plus ça change, plus c'est la même chose.
Principles was not quite the epoch-making break with the past that later historical mythologizing made it out to be. Still, its importance was noticed by almost everyone, not least by Whewell, who wrote a lengthy review of Volume 1 in 1831. In it, Whewell noted Lyell's tendency to slip between methodological proposals—like the idea that geologists should “frame theories in accordance with the ordinary operations of nature”—and theoretical ones—like the claim that extraordinary causes have not operated at any point in earth's history. The former were by and large unobjectionable, and were already the common currency of most serious geologists by 1830. The latter, by contrast, were adventurous speculations that ran well beyond the available evidence, and even seemed to contravene it at key points. When approached in this light there was no big issue. One could easily enough accept the methodological principles while rejecting the theoretical claims as unfounded. The problem was that Lyell maintains no such separation in the text, and often wrote as if the theoretical ideas were implied by the methodological ones. This, Whewell saw, was a recipe for mischief.
Whewell and Lyell were not enemies. To the contrary, it was Lyell who orchestrated Whewell's election to the presidency of the Geological Society (succeeding Lyell himself), in part to deny the position to the eccentric, and potentially embarrassing, William Buckland. Whewell in turn praised Lyell for raising geological dynamics to “its proper prominent position” in geology. Lyell had forerunners in geological dynamics, the most important of which was a German, Karl Ernst Adolf von Hoff, who in several large volumes had “collected from ancient and modern writers a very large body of curious information" (Whewell 1831, 195). Yet it was only with the publication of Principles that “the full effect of such [information]” was made manifest, since this work “present[ed] such assemblages of special facts, as examples of general laws” (Whewell 1837, 552). Whewell praised Lyell for taking this important step, even while he cautioned that “several generations must [yet] elapse” before geological dynamics could reach the status of an exact science (554).
So, Lyell was to be commended for expanding geology’s explanatory toolkit. Where he could be faulted was for a certain hastiness in generalization: for a penchant to vault from laws, imperfectly established, to highly speculative theoretical claims. An example was the claim “that all the phenomena of the earth’s strata may be considered as produced by a continuous series of events, of which changes now occurring are fair examples” (Whewell 1831, 199). This was “Uniformitarianism,” as Whewell understood it, and was guilty of a slew of philosophical sins. An especially outrageous one involved Lyell’s claim that the “doctrine of uniformity” had “a great degree of à priori probability,” which could be established in advance of any of its applications:
It is highly unphilosophical, it has been urged, to assume that the causes of the geological events of former times were of a different kind from causes now in action, if causes of this latter kind can in any way be made to explain the facts. The analogy of all other sciences compels us, it was said, to explain phenomena by known, not by unknown, causes. And on these grounds the geological teacher recommended “an earnest and patient endeavour to reconcile the indications of former change with the evidence of gradual mutations now in progress.” (Whewell 1840, 126)
Whewell agreed with Lyell that geologists should eschew wanton speculation. Whether past convulsions of the crust have been gradual or catastrophic was something that “must be collected… from the facts of the case,” supposing all the while that “the causes which have produced geological phenomena, have been as similar to existing causes, [or] as dissimilar, as the effects teach us” (Whewell 1837, 615). But this was not what Lyell recommended. For Lyell, it was a principle of reasoning that geological agencies have never acted with different degrees of intensity than those which they presently exert. He said as much in a letter to Roderick Murchison, in which he claimed that his book “will endeavour to establish the principle[s] of reasoning in… [geology]… which [are] that no causes whatever have from the earliest time to which we can look back, to the present, ever acted, but those now acting; and that they never acted with different degrees of energy from that which they now exert.” But this, Whewell said, was an “altogether arbitrary and groundless” assumption (Whewell 1840, 126). “We must learn from an examination of all the facts, and not from any assumption…, whether the course of nature [has been] uniform.” We have nothing to gain from yoking ourselves to an a priori view about the rate and intensity of geological processes, especially when this is at variance with the testimony of the rocks. Whewell drove the point home with a comparison between time (the uniformitarian's best friend) and force (a quantity that the uniformitarian is concerned to restrict):
Time… can undoubtedly do much for the theorist in geology; but Force… is also a power never to be slighted: and to call in one to protect us from the other, is equally presumptuous, to whichever of the two our superstition leans. To invoke Time, with ten thousand earthquakes, to overturn and set on edge a mountain-chain, should the phenomena indicate the change to have been sudden and not successive, would be ill excused by pleading the obligation of first appealing to known causes. (Whewell 1840, 616)
How had Lyell made such a blunder? Whewell’s answer, curiously, is that he had been too Newtonian, at least in the sense of hewing too close to what Newton said in the General Scholium (1726). This was where Newton laid out his rules for reasoning in natural philosophy, including the famous first rule: “No more causes of natural things should be admitted than are both true and sufficient to explain their phenomena.” In Thomas Reid’s explication, this meant (1) that the causes “ought to be true, to have a real existence, and not to be barely conjectured to exist without proof”; and (2) that they “ought to be sufficient to produce the effect.” (This is usually called the vera causa rule, or principle.)
The second part of the rule is uncontroversial. It simply says that causes should be capable of producing the effects they are adduced to explain. The first part, by contrast, is more contentious. It is often read as a prescription that says, in Whewell’s words, that we must assume no other causes than those we know “from other considerations . . . to exist” (Whewell 1840, 441). But such an injunction is “an injurious limitation of the field of induction… [for] it forbids us to look for a cause, except among the causes with which we are already familiar" (Whewell 1840, 441–2). If the upturned strata of the Isle of Wight seem to indicate a period of convulsive elevation, why should we limit ourselves to explaining them by little upward nudges, just because the latter happen to have been observed? In short, “Why should we not endeavor to learn the cause from the effects, even if [the cause] be not already known to us?”
Whewell was not completely sour on Newton’s first rule. He just favored a different criterion for the reality of a cause: consilience. “When the explanation of two kinds of phenomena, distinct and not apparently connected, leads us to the same cause, such a coincidence [or consilience] does give a reality to the cause, which it has not while it merely accounts for those appearance which suggested the supposition” (Whewell 1840, 446). Curiously, Whewell was little impressed by the most successful consilient argument in the history of the palaetiological sciences: Darwin’s argument in the Origin of Species. But this is because it transgressed what Whewell saw as the clearly-defined limits of palaetiological science. For Whewell, an inductive science of origins barely made sense. Here was another difference from Darwin’s mentor Lyell, the champion of continuity in geohistory.
* * *
Whewell was the most astute of Lyell's critics. In a series of publications, he dissected the basic assumptions of Lyellian geology, while simultaneously bolstering the opposition. But as Jon Hodge observes, Whewell’s most persistent preoccupation as a writer on geology was not the adjudication of internal geological disputes (Hodge 1991). Instead, his concern was to place limits on geology’s rightful sphere of operations. This was important since geology, for Whewell, included not only stratigraphy and geological dynamics, but also biogeography and speculations about the origin of species (including man). This created the need for some way of resolving— or better, avoiding— territorial disputes. Who has the right of way in these cases? Or, to put a different spin on things: how can we identify the limits of geology and theology, such that confrontations on matters of shared concern can be decisively headed off?
There was no shortage of literature on geology and scripture in Great Britain, much of it concerned with establishing a correspondence between geological findings and the Genesis narrative (O’Connor 2007). Whewell’s interests were different. As a cleric, Whewell was committed to the truth of scripture, yet as a scientist (and a booster of British science in particular) he was interested in securing for geology a wide scope of application. How to avoid conflict? The key, as it turned out, was to define a limit to what geologists could conceivably know. This would secure for geology a maximally wide scope of application within the sphere of its legitimate activity, while at the same time guaranteeing that the progress of geology would at no point exclude the operation of a first cause. Geology need not be threatening to Christians, nor Christianity to geology. All that was needed was a little philosophy.
So what did Whewell take the limits of geological investigation to be? Despite his reputation as a conservative thinker, Whewell granted that geology can “go very far back” in its inquiries: it can “determine many of the remote circumstances of the past sequence of events;—ascend to the point which, from our position, at least, seems to be near the origin;—and exclude many suppositions respecting the origin itself” (Whewell 1837, 581). Still, it remains “no irrational opinion” to say “that in all those sciences which look back and seek a beginning of things, we may be unable to arrive at a consistent and definite belief, without having recourse to other grounds of truth” (582). The reason is that, while the palaetiological sciences direct us “by an inevitable consequence… to look for the beginning of the state of things which we thus contemplate,”
in none of these [areas] have men been able, by the aid of science, to arrive at a beginning which is homogeneous with the known course of events. The first origin of language, of civilization, of law and government, cannot be clearly made out by reasoning and research; and just as little, we may expect, will a knowledge of the origin of the existing and extinct species of plants and animals, be the result of physiological and geological investigation. (Whewell 1837, 581)
The same holds true for all reasoning about the present order, from whose origin we are “separated by a state of things, and an order of events, of a kind altogether different from those which come under our experience” (Whewell 1840, 145). It follows that the palaetiological sciences can have nothing to say about beginnings. As we approach the beginning of the present causal order, “[the] thread of induction respecting the natural course of the world snaps in our fingers.” The most geology can say is that there is a beginning; it cannot say what caused it.*
[* To better understand Whewell's position, it is useful to recall that early nineteenth century geologists often described the task of geology as recovering a single prehuman world, or later, a succession of worlds. Such language implied a succession of causal orders separated by discontinuities, not the more dynamic continuum of later conceptions of deep history (Rudwick 2005).]
Now this, it has to be said, is a strange argument. If geology can carry its investigations “very far back,” then why can’t it carry them all the way back to the beginning? Why must it slam into a wall where chains of causation have their origin? In short, why do things like the origin of species fall outside the scope of palaetiological science? Whewell seems to argue that because science has failed to account for beginnings so far, it is incapable of doing so. But this is a dim view to take of things. Whewell does not say that geologists are incapable of achieving a Physical Geology because no one has yet framed a complete and true physical theory. So why should things be different with inquiry into origins?
Presumably the answer has something to do with the nature of causes responsible for origins, which might be called “first causes,” or truly creative causes. These are classed with the historical causes since their operation is confined to a particular interval of time. But unlike ordinary historical causes, which cause events to occur in keeping with extant physical laws, creative causes bring new regimes of order into being, and thus involve the origin of causal laws. When a new species or language is born created, the rules change (so to speak), and it is beyond the capacity of inductive methods to account for it. And since science “can teach us nothing positive respecting the beginning of things, she can neither contradict nor confirm what is taught by Scripture on that subject” (Whewell 1840, 145).
It is important to observe that Whewell’s delimitation cuts both ways. It is not just that he limits geology to make room for God, as Kant denied knowledge to make room for faith. In addition, Whewell insists that “religious and enlightened commentator[s]” must sometimes alter their interpretations of scripture to accommodate geological findings (Whewell 1840, 147). He cites a rule on this subject, “propounded by some of the most enlightened dignitaries of the Roman Catholic church, on the occasion of the great Copernican controversy,” to regulate scriptural interpretation (148). The rule states that “When a demonstration shall be found to establish the earth’s motion, it will be proper to interpret the sacred Scriptures otherwise than they have hitherto been interpreted in those passages where mention is made of the stability of the earth and movement of the heavens.” Likewise, when a geological proposition can be established by adequate proofs, the interpretation of scripture must be modified to accommodate the finding. Whewell is careful to say that this should not be done hastily, “as [when] the supposed scientific discovery is doubtful.” Yet “when a scientific theory, irreconcilable with [an] ancient interpretation, is clearly proved, we must give up the interpretation, and seek some new mode of understanding the passage in question, by means of which it may be consistent with what we know.” The scope of conflict between geology and scripture is thus limited to haggling over what constitutes a clear proof of a geological thesis, capable of destabilizing a traditional interpretation of scripture.
I am aware that this treatment of Whewell runs the risk of making him seem more modern and ecumenical than he was. In fact, Whewell makes clear throughout his writings that only the “distinct manifestation of creative power, transcending the known laws of nature” can account for real origins (Whewell 1831, 194). Geology can never show that God did this or that, but it can show that certain occurrences “are quite inexplicable by the aid of any natural causes with which we are acquainted” (Whewell 1840, 116). In these cases, as Whewell famously said of the species problem, geology “says nothing, but she points upwards.” By showing the impossibility of discovering “a beginning which is homogenous with the known course of events,” the palaetiological sciences demonstrate the necessity of seeking a cause that is inhomogeneous with the known course of events, which is to say, a supernatural one.
* * *
I began this essay by expressing dissatisfaction with the phrase “philosophy of paleontology.” Am I now prepared to call myself a “philosopher of palaetiology”? I am not. Some words pass out of usage for a reason, and while palaetiology is hardly an ugly word, it doesn't exactly trip off the tongue.
Still, I am inclined to give the final word to Whewell, who happens to be one of my favorite philosophers. So here he is, describing the content of a well-rounded liberal education. After suggesting that the “chemical sciences” are not presently “in a condition which makes them important general elements of a liberal education,” Whewell notes that there is another class of sciences, the palaetiological, “which, from the largeness of their views and the exactness of the best portions of their reasonings, are well fitted to form part of that philosophical discipline which a liberal education ought to include.”
These [sciences], [including] ethnography, or comparative philology, and geology, are among those progressive sciences which may be most properly taken into a liberal education as instructive instances of the wide and rich field of facts and reasonings with which modern science deals, still retaining, in many of its steps, great rigour of proof; and as an animating display also of the large and grand vistas of time, succession, and causation, which are open to the speculative powers of man. (Whewell 1845, 20)
Let these words stand as an advertisement for Extinct: The Philosophy of Palaetiology— er, Palaeontology— Blog!
* A much expanded version of this analysis (from which the present remarks are adapted) will appear in the forthcoming volume William Whewell: Victorian Polymath from Pittsburgh University Press.
References
Bakewell, R. 1815. An Introduction to Geology: Comprising the Elements of the Science in its Present Advanced State and all the Recent Discoveries; with an Outline of the Geology of England and Wales. London: Longman, Hurst, Orme, Brown, and Green.
De la Beche, H.T. 1834. Researches in Theoretical Geology. London: Charles Knight.
Fitton, W. 1817. Transactions of the Geological Society, established 1807. Edinburgh Review 18:70– 94.
Hodge, M.J.S. 1991. The history of the earth, life, and man: Whewell and palaetiological science. In M. Fisch and S. Schaffer (Eds.), William Whewell: A Composite Portrait, 253–288. Oxford: Oxford University Press.
Lyell, C. 1830. Principles of Geology, Being an Attempt to Explain the Former Changes of the Earth’s Surface, by Reference to Causes now in Operation. Volume 1 (First Edition). London: John Murray.
O’Connor, R.O. 2007. The Earth on Show: Fossils and the Poetics of Popular Science, 1802-1856. Chicago: The University of Chicago Press.
Rudwick, M.J.S. 1985. The Great Devonian Controversy: The Shaping of Scientific Knowledge Among Gentlemanly Specialists. Chicago: University of Chicago Press.
Rudwick, M.J.S. 2005. Bursting the Limits of Time: The Reconstruction of Geohistory in the Age of Revolution. Chicago: University of Chicago Press.
Whewell, W. 1831. Lyell’s Principles of Geology, Volume 1. British Critic and Quarterly Theological Review 9:180–206.
Whewell, W. 1837. History of the Inductive Sciences, from the Earliest to the Present Time. London: John W. Parker.
Whewell, W. 1840. Philosophy of the Inductive Sciences, Founded upon their History. London: John W. Parker.
Whewell, W. 1845. Of a Liberal Education in General. London: John W. Parker.
For Some Additional Resources on Whewell, see:
Dethier, C. 2018. William Whewell’s semantic account of induction. HOPOS 8:141–156.
Snyder, L.J. 2006. Reforming Philosophy: A Victorian Debate on Science and Society. Chicago: University of Chicago Press.
Snyder, L.J. 2011. The Philosophical Breakfast Club: Four Remarkable Friends who Transformed Science and Changed the World. New York: Broadway Books.
Quinn, A. 2016. William Whewell’s philosophy of architecture and the historicization of biology.” Studies in History and Philosophy of Biological and Biomedical Sciences 59:11–19.
Quinn, A. 2017. Whewell on classification and consilience. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences 1:65–74.
Yeo, R. 1993. Defining Science: William Whewell, Natural Knowledge, and Public Debate in Early Victorian Britain. Cambridge: Cambridge University Press.