In 1995 the Galileo spacecraft captured data about Jupiters atmosphere-namely, the absence of most of the predicted atmospheric water-that challenged prevailing theories about Jupiters structure. The unexpectedness of this finding fits a larger pattern in which theories about planetary composition and dynamics have failed to predict the realities discovered through space exploration. Instead of normal planets whose composition could be predicted by theory, the planets populating our solar system are unique individuals whose chemical and tectonic identities were created through numerous contingent events. One implication of this is that although the universe undoubtedly holds other planetary systems, the duplication of the sequence that produced our solar system and the development of life on Earth is highly unlikely.
Recently planetary scientists have suggested that the external preconditions for the development of Earth`s biosphere probably included four paramount contingencies. First, a climate conducive to life on Earth depends upon the extraordinarily narrow orbital parameters that define a continuously habitable zone where water can exist in a liquid state. If Earths orbit were only 5 percent smaller than it is, temperatures during the early stages of Earths history would have been high enough to vaporize the oceans. If the Earth-Sun distance were as little as 1 percent larger, runaway glaciation on Earth about 2 billion years ago would have caused the oceans to freeze and remain frozen to this day. Second, Jupiter`s enormous mass prevents most Sun-bound comets from penetrating the inner solar system. It has been estimated that without this shield, Earth would have experienced bombardment by comet-sized impactors a thousand times more frequently than has actually been recorded during geological time. Even if Earth`s surface were not actually sterilized by this bombardment, it is unlikely that any but the most primitive life-forms could have survived. This suggests that only planetary systems containing both terrestrial planets like Earth and gas giants like Jupiter might be capable of sustaining complex life-forms.
Third, the gravitational shield of the giant outer planets, while highly efficient, must occasionally fail to protect Earth. Paradoxically, while the temperatures required for liquid water exist only in the inner solar system, the key building blocks of life, including water itself, occur primarily beyond the asteroid belt. Thus the evolution of life has depended on a frequency of cometary impacts sufficient to convey water, as well as carbon and nitrogen, from these distant regions of the solar system to Earth while stopping short of an impact magnitude that would destroy the atmosphere and oceans.
Finally, Earth`s unique and massive satellite, the Moon, plays a crucial role in stabilizing the obliquity of Earth`s rotational axis, this obliquity creates the terrestrial seasonality so important to the evolution and diversity of life. Mars, in contrast, has a wildly oscillating tilt and chaotic seasonality, while Venus, rotating slowly backward, has virtually no seasonality at all.
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The passage is primarily concerned with
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Until around 1930 few United States Civil War historians paid much attention to Southerners who opposed the 1861-1865 secession from the United States by a confederacy of Southern states. Southern historians clung instead to a notion of the South`s unanimity in the face of Northern aggression. Only when scholars such as Lonn decided to examine this side of the war did historian of the Confederacy begin to recognize the existence of Southerners loyal to the Union (Unionists). While these early historians of Southern dissent broke new ground, they also reproduced Confederate authoritie`s negative view of loyalists as shady characters driven by dubious motives. Even Tatum, who took a largely sympathetic attitude toward loyalists, tended to lump them into nebulous categories, offering broad generalizations that ignored the particulars of Unionists` identities and experiences.
This early-twentieth-century historiography nonetheless represented the leading research on dissent in the South until the 1960s and 1970s. Spurred by the advent of social historical methods, a new generation of historians found Unionists interesting as manifestations of the Confederacy`s internal weaknesses. Focusing on the Appalachian Mountain and upper South regions of the Confederacy, these scholars argued that there was a profound divide among Southern Whites between those who benefited economically from slave-run plantations and those who did not. One such historian was Escott, who emphasized regional and economic conflict among Southerners. Escott cast Unionists and other dissenters as antiplanter mountaineers who could not, by reason of economic and social alienation, identify with the proslavery Southern cause. This theme has heavily influenced the work of subsequent scholars, who commonly place Unionists at the extreme end of a continuum of class-based Confederate disaffection that was ultimately responsible for the South`s collapse. Because the driving force behind such inquiries into loyalist history has been a desire to explain Confederate ideology, politics, and defeat, emphasis has been placed on the ways loyalist Southerners diverged from the political and economic mainstream of Confederate nationalism.
Only recently have some Civil War historians begun to make Unionists and their experiences, rather than the Confederate state, the center of inquiry. These scholars have done intensive community and local studies of dissenting groups that take into account a range of social and cultural, as well as military and political, factors at work on the Southern home front. Hoping to better understand who remained loyal to the Union during the war, these historians have sought to explain the Civil War`s underlying character, dimensions, and impact in particular counties or towns, especially in the upper South and Appalachia. This relatively new trend has stressed the particular, delved into the complexities of political allegiances on the home front, and, as Sutherland notes, highlighted "the gritty experience of real people".
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The primary purpose of the passage is to
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In his recent book, Louis Gerteis argues that nineteenth-century Northern reformers in the United States attacked slavery in the South by invoking the values of a utilitarian political economy: proper public policy requires government to endorse anything that gives all people the opportunity to maximize their individual pleasure and their material gain. Social good, according to this thinking, is achieved when individuals are free to pursue their self-interests. Gerteis argues that, since slavery in the South precluded individual autonomy and the free pursuit of material gain, major Northern reformers opposed it as early as the 1830s.
In making this argument, Gerteis offers the most persuasive formulation to date of the Growth of a Dissenting Minority interpretation, which argues that a slow but steady evolution of a broad-based Northern antislavery coalition culminated in the presidential victory of the antislavery Lincoln in 1860. This interpretive framework, which once dominated antislavery historiography, had been discounted by historians for two basic reasons. First, it tended to homogenize the political diversity of Northern reformers; Northern reformers differed significantly among themselves and belonged to diverse political parties. Second, it seemed incompatible with emerging scholarship on the slaveholding South, which held that Northern abolitionists of the 1830s did not succeed in mobilizing Northern public opinion and paving the way for Lincoln in 1860. Instead, Southern slaveholders misconstrued abolitionist views of the 1830s as main- stream rather than marginal Northern public opinion, and castigated Northerners generally for opposing slavery. In this view, it was the castigation by Southerners that gradually caused widespread antislavery feeling throughout the North.
Gerteis revives the Growth interpretation by asserting that, rather than Southern attitudes, the unified commitment of Northern reformers to utilitarian values served to galvanize popular political support for abolitionism. However, unlike earlier proponents of the Growth interpretation, Gerteis does not reduce the Northern reformers to a homogeneous group or try to argue that the reformers shared views undermined their differing party loyalties. Members of the two major political parties still attacked each other for ideological differences. Nevertheless, Gerteis argues, these disparate party affiliations did not diminish the actuality of reformer unity, most prominent in the 1830s. At this time, Northern reformers, such as William Lloyd Garrison and Samuel Chase, portrayed the framers of the United States Constitution as proponents of individual autonomy and capitalist values. This vision of the founders served as a basis for asserting that freedom was a national moral imperative, and that the United Sates Constitution was an antislavery document. Gerteis differs from traditional adherents of the Growth framework by asserting that the basic elements in the antislavery coalition were firmly in place and accepted by all elements in the Northern reform community as early as the late 1830s.
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The author would be most likely to agree with which of the following about Gerteis' formulation of the "Growth" interpretation?
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The passage supports which of the following statements about the "Growth" interpretation?
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Historian E.H Carr`s thesis that all debates concerning the explanation of historical phenomena revolve around the question of the priority of causes is so familiar to historians as to constitute orthodoxy within their profession. The true historian,as Carr puts it, will feel a professional obligation to place the multiple causes of a historical event in a hierarchy by means of which the primary or ultimate cause of the event can be identified. In the Marxist mode of historical explanation (historical materialism), a universal hierarchy of causes is posited in which economic factors are always primary. In the classic, more widely accepted alternative ultimately derived from Weberian sociology, hierarchies of causes are treated as historically specific: explanatory primacy in any particular historical situation must be established by empirical investigation of that situation, not by applying a universal model of historical causation.
While the need to rank historical causes in some order of importance may seem obvious to most historians, such hierarchies raise serious philosophical difficulties. If any historical event is the product of a number of factors, then each of these factor is indispensable to the occurrence of the event. But how can one cause be more indispensable than another? And if it cannot, how can there be a hierarchy of indispensable causes? It was this problem that first led Weber himself to argue for the impossibility of any general formula specifying the relative importance of causes; we cannot, for example, conclude that in every capitalist society religious change has been more significant than economic change (or vice versa) in explaining the rise of capitalism.
Runciman offers a different argument leading to the same conclusion. He points out that it is possible to identify specific factors as the primary causes of a particular historical event only relative to an initial set of background conditions. For instance, if we accept English defeats after 1369 in the Hundred Years War as a given, then we may identify the high levels of taxation necessitated by these military reverses as the main cause of the Peasants Revolt of 1381. If instead we regard the financing of warfare by taxation in this period as a background condition, then we will see the English reverses themselves as the main cause of the revolt. However, neither ordinary life nor historical practice offer reliable criteria by which to distinguish causes from background conditions and thus to resolve historical debates about the relative importance of causes. And this difficulty casts doubt not only on the Marxist effort to identify a universal hierarchy of causes, but also on any attempt to identify an objective hierarchy of causes–even of the historically specific kind favored by non-Marxists.
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The primary purpose of the passage is to
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According to the passage, most historians share the assumption that
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In the second paragraph of the passage, the author uses the concept of an indispensable cause primarily in order to question which of the following claims?
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