by Judith Curry
We are also told of general catastrophes and a succession of deluges, of the alternation of periods of repose and disorder, of the refrigeration of the globe, and of the sudden annihilation of whole races of animals and plants, and other hypotheses, in which we see the ancient spirit of speculation revived, and a desire manifested to cut, rather than patiently to untie, the Gordian knot. – Charles Lyell
I received via email this text excerpted from the classical text Principles of Geology, by Charles Lyell (1st ed.. Vol. Ill, pp. 1-5, London, 1833). Charles Lyell is generally regarded as the father of modern geology. Here is the excerpted text:
All naturalists, who have carefully examined the arrangement of the mineral masses composing the earth’s crust, and who have studied their internal structure and fossil contents, have recognized therein the signs of a great succession of former changes; and the causes of these changes have been the object of anxious inquiry. As the first theorists possessed but a scanty acquaintance with the present economy of the animate and inanimate world, and the vicissitudes to which these are subject, we find them in the situation of novices, who attempt to read a history written in a foreign language, doubting
about the meaning of the most ordinary terms; disputing, for example, whether a shell was really a shell, whether sand and pebbles were the result of aqueous trituration, whether stratification was the effect of successive deposition from water; and a thousand other elementary questions which now appear to us so easy and simple, that we can hardly conceive them to have once afforded matter for warm and tedious controversy.
In the first volume we enumerated many prepossessions which biased the minds of the earlier inquirers, and checked an impartial desire of arriving at truth. But of all the causes to which we alluded, no one contributed so powerfully to give rise to a false method of philosophizing as the entire unconsciousness of the first geologists of the extent of their own ignorance respecting the operations of the existing agents of change.
They imagined themselves sufficiently acquainted with the mutations now in progress in the animate and inanimate world, to entitle them at once to affirm, whether the solution of certain problems in geology could ever be derived from the observation of the actual economy of nature, and having decided that they could not, they felt themselves at liberty to indulge their imaginations, in guessing at what might be, rather than in inquiring what is: in other words, they employed themselves in conjecturing what might have been the course of nature at a remote period, rather than in the investigation of what was the course of nature in their own times.
It appeared to them more philosophical to speculate on the possibilities of the past, than patiently to explore the realities of the present, and having invented theories under the influence of such maxims, they were consistently unwilling to test their validity by the criterion of their accordance with the ordinary operations of nature. On the contrary, the claims of each new hypothesis to credibility appeared enhanced by the great contrast of the causes of forces introduced to those now developed in our terrestrial system during a period, as it has been termed, of repose.
Never was there a dogma more calculated to foster indolence, and to blunt the keen edge of curiosity, than this assumption of the discordance between the former and the existing causes of change. It produced a state of mind unfavorable in the highest conceivable degree to the candid reception of the evidence of those minute, but incessant mutations, which every part of the earth’s surface is undergoing, and by which the condition of its living inhabitants is continually made to vary. The student, instead of being encouraged with the hope of interpreting the enigmas presented to him in the earth’s structure, instead of being prompted to undertake laborious inquiries into the natural history of the organic world, and the complicated effects of the igneous and aqueous causes now in operation, was taught to despond from the first.
Geology, it was affirmed, could never rise to the rank of an exact science; the greater number of phenomena must forever remain inexplicable, or only be partially elucidated by ingenious conjectures. Event the mystery which invested the subject was said to constitute one of its principal charms, affording, as it did, full scope to the fancy to indulge in a boundless field of speculation.
The course directly opposed to these theoretical views consists in an earnest and patient endeavor to reconcile the former indications of change with the evidence of gradual mutations now in progress; restricting us, in the first instance, to known causes, and then speculating on those which may be in activity in regions inaccessible to us. It seeks an interpretation of geological monuments by comparing the changes of which they give evidence with the vicissitudes now in progress, or which may be in progress.
We are now, for the most part, agreed as to what rocks are of igneous, and what of aqueous origin, in what manner fossil shells, whether of the sea or of lakes, have been imbedded in strata, how sand may have been converted into sandstone, and are unanimous as to other propositions which are not of a complicated nature; but when we ascent to those of a higher order, we find as little disposition, as formerly, to make a strenuous effort, in the first instance, to search out an explanation in the ordinary economy of Nature. If, for example, we seek for the causes why mineral masses are associated together in certain groups; why they are arranged in a certain order which is never inverted; why there are many breaks in the continuity of the series; why different organic remains are found in distinct sets of strata; why there is often an abrupt passage
from an assemblage of species contained in one formation to that in another immediately superimposed; when these and other topics of an equally extensive kind are discussed, we find the habit of indulging conjectures, respecting irregular and extraordinary causes, to be still in full force.
We hear of sudden and violent revolutions of the globe, of the instantaneous elevation of mountain chains, of paroxysms of volcanic energy, declining according to some, and according to others increasing in violence, from the earliest to the latest ages. We are also told of general catastrophes and a succession of deluges, of the alternation of periods of repose and disorder, of the refrigeration of the globe, and of the sudden annihilation of whole races of animals and plants, and other hypotheses, in which we see the ancient spirit of speculation revived, and a desire manifested to cut, rather than patiently to untie, the Gordian knot.
In our attempt to unravel these difficult questions, we shall adopt a different course, restricting ourselves to the known or possible operations of existing causes; feeling assured that we have not yet exhausted the resources which the study of the present course of nature may provide, and therefore that we are not authorized, in the infancy of our science, to recur to extraordinary agents.
We shall adhere to this plan, not only on the grounds explained in the first volume, but because, as we have above stated, history informs us that this method has always put geologist on the road that leads to truth, suggesting views which, although imperfect at first, have been found capable of improvement, until at last adopted by universal consent. On the other hand, the opposite method, that of speculating on a former distinct state of things, has led invariably to a multitude of contradictory systems, which have been overthrown one after the other, which have been found quite incapable of modification, and which are often required to be precisely reversed.
In our attempt to solve geological problems, we shall be called upon to refer to the operation of aqueous and igneous causes, the geographical distribution of animals and plants, the real existence of species, their successive extinction, and so forth. We are under the necessity of collecting together a variety of facts, and of entering into long trains of reasoning, which could only be accomplished in preliminary treatises.
These topics we regard as constituting the alphabet and grammar of geology; not that we expect from such studies to obtain a key to the interpretation of all geological phenomena, but because they form the groundwork from which we must rise to the contemplation of more general questions relating to the complicated results to which, in an indefinite lapse of the ages, the existing causes of change may give rise.
JC reflections
Lyell’s essay provides some words of wisdom as we seek a coherent philosophy of natural science in the 21st century, particularly as related to climate change. Our understanding of climate variability and change on decadal to century relative to the maturity of geology in the 19th century can only be assessed in hindsight: are we in the infancy of our science?
The primacy of the epistemic status of climate models as a source of alarming and catastrophic predictions seems to be an attempt to cut the Gordian knot of understanding climate change rather than to unravel the knot.
We are under the necessity of collecting together a variety of facts, and of entering into long trains of reasoning. The current climate modeling imperative is effectively relegating observations to a lower epistemic status, and diminishes the importance of actually reasoning about the information. A notable example of this is the AR4 conclusions about climate sensitivity, which were driven primarily by climate model simulations; in AR5 climate model simulations of sensitivity were given equal weight to observation derived values. Climate models diminish the importance of actually reasoning about diverse types of evidence. How to actually reason about the complex evidence and the uncertainties remains a daunting and largely unexamined task (see my paper Reasoning About Climate Uncertainty); instead too many people just plot the output of climate models.
Next week (!) I will be attending a Conference at the Rotman Institute of Philosophy on Knowledge and Models in Climate Science, which is addressing the epistemic status of climate models. I am very pleased to see these broad issues being pondered by philosophers of science, and I look forward to learning from them.Filed under: Scientific method
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