BCS Home
Scientific Issues
The Discovery of Geological Time

Religious and philosophical inputs to geochronology
David J. Tyler


The Legacy of the Greeks
Aquinas' synthesis of Aristotelian philosophy and Catholic theology
Galileo and the "Two Books"
Early science and the adoption of Baconian principles
Geology and the "Two Books"


In geological circles, it is now unquestioned that the Earth has had a history measured in billions of years. But how do we know this? One geologist known to the writer said in conversation that the age of the Earth is a question answered by physics - he was referring to radiometric dating and he speaks for many. Historically, geological timescales were not "determined by physics", but by the adoption of certain methodological principles of interpretation of geologic data. This paper attempts to trace some of the critical intellectual changes that were involved in the acceptance of long geological ages, showing that the changes had more to do with philosophical presuppositions rather than "objective" science. The question as to whether present day techniques for dating the Earth and its rocks are similarly affected by presuppositions lies outside the scope of this paper, but it is suggested that the issues discussed here are a foundation for providing an answer. 

A further consideration to justify the themes addressed has been the tendency of some creationist writers on the history of science to present an unbalanced perspective on trends in 19th century geology. The issue has sometimes been presented as a controversy between uniformitarianism (championed by Charles Lyell) and catastrophism (used as a synonym for Flood Geology). The problem is that the majority of catastrophists in the 19th century already accepted long geological ages! Flood Geology was generally considered by catastrophists to be responsible for just the Diluvium (recognised later in that century as glacial deposits). If we want to find out what factors were responsible for the acceptance of extended geological time, we must look earlier than the 19th century! 

The Legacy of the Greeks

The history of scientific thought demonstrates very clearly the important influence of dominant worldviews. The ancient Greeks were impressive philosophers, mathematicians and astronomers. However, they failed to provide a foundation for scientific study because they were too disposed to be deductive thinkers: their world-view affected the way they approached the data before them. 

Nevertheless, the strengths of their philosophical, mathematical and astronomical work meant that their influence continued long after the flowering of Greek culture. 

During the Middle Ages, people began to realise that their Church-based scholarship was languishing and a new impetus was needed. Then they rediscovered the Greeks. Aristotelian philosophy soon made an extraordinary impact. His writings were considered to surpass those of the others in terms of depth and diversity of interests. People read Aristotle on physics, metaphysics, logic, cosmology, the elements, epistemology and the nature of change. He extended their minds; he excited their imagination. 

Significantly, these years saw the emergence of the universities as centres of intellectual activity. The staff of these institutions did not perceive themselves as being just a different kind of seminary - rather, they had their own independent identity. It was accepted that theology had to be the most important faculty, but the theologians were not allowed to control every other faculty. The writings of Aristotle gripped these scholars: there had been an intellectual vacuum in most disciplines which nothing else seemed to fill. As a result, Aristotelianism became the entrenched orthodoxy in universities from 1200 until the middle of the 17th century. 

Aquinas' synthesis of Aristotelian philosophy and Catholic theology

There was no question that Aristotle was a pagan Greek philosopher and that his approach was in tension with that of the Church scholars. This situation had to be addressed. It came to a head first in the University of Paris, where some theologians and nearly all the arts masters became Aristotelians. 

This made the more traditional theologians (who were the majority) very uneasy. The result was a ban on Aristotle's books relating to natural phenomena in 1210 and 1215, and an attempt to expurgate them in 1231. Despite rearguard efforts like this, Aristotle became, in time, to be the core of the curriculum, leaving a large number of traditionally-minded theologians convinced that things were being taught subversive to the faith (Grant, 1986). 

Thomas Aquinas (1225-1274) had the confidence of the traditionalists and yet he saw Aristotle as the greatest of human philosophers: someone achieving the highest level of human thought without the aid of revelation. Aquinas proposed a way of incorporating the essence of Aristotle into the Christian intellectual tradition. He did it by arguing that the world of nature could be known separately from the world of the spirit. The sacred could be distinguished from the secular. Using more contemporary terminology, Aquinas compartmentalised knowledge. 

Two-book compartmentalisation

This, in my view, was an approach to knowledge which has been extraordinarily influential within the Catholic tradition and outside it. Many intellectual leaders have adopted the same strategy of organising knowledge in compartments which do not communicate. It has been called the "double revelation" approach: "God reveals himself separately in the natural world and in the spiritual world". It is also known as the "two books" approach: "There is a book of nature which can be read separately from the book of the Spirit. These books belong to two distinct domains of knowledge and are largely independent of each other"

It must be said that Aquinas' synthesis was not accepted immediately. Many traditional theologians continued to speak about the subversive character of Aristotelianism. However, these voices faded with time, and Aristotelian philosophy became the orthodoxy for all secular studies. 

Although not presented in the same context, Schaeffer's books Escape from reason (1986) and The God who is there (1986) have drawn attention to Aquinas' legacy to succeeding generations in philosophy and many other disciplines of knowledge. He refers to "the teaching of a man who changed the world in a very real way". The basic arguments of this paper relating to the compartmentalisation of knowledge were stimulated by Schaeffer's analysis of the history of ideas. 

Galileo and the "Two Books"

The double revelation theory was brought into action when Copernican astronomy became the focus of attention. The problem was not simply that the Bible appeared to teach geocentrism; the more fundamental conflict was that the academic world was wedded to Aristotelian philosophy which was committed to geocentrism as a matter of logical necessity. Those who employed the "two books" argument to defend Copernicanism were keen to emphasise the autonomy of science and quick to complain about people meddling in matters where they had no expertise. Thus Galileo wrote: 

Galileo used the "two books" argument freely, but how did he handle the question of the relationship of the two books to each other? He argued that in the natural world, there is objectivity and clarity which may not be found by reading the scripture - which uses words adapted to common understanding. In areas of conflict about natural phenomena, the revelation obtained from the natural world should be preferred.  Galileo was a controversial figure in his day - and there is much in his life and writings that cannot be commended. However, he has been seen as a champion of science who was basically right about Copernicanism - and he has become, for generations of scientists, a role model giving us the principles of scientific freedom. As a result, many have accepted on trust the "two books" approach to knowledge. 

Early science and the adoption of Baconian principles

It took the Reformation to break down man's pride in his own abilities, to promote a spirit of seeking after truth as an expression of worship; and to motivate men in the use of this knowledge to "subdue the earth" in obedience to God's command. The relationship between spiritual and natural knowledge was a secondary issue during the Reformation, and there are indications that traditional Christian thinking in this area was inadequately reformed. The idea that God has revealed himself in the Book of Nature and the Book of Scripture was popularly held by Protestants. 

The influential Francis Bacon incorporated the "two books" into his philosophy: which is widely regarded as having supported and stimulated the rise of genuine science. Certainly, it provided inspiration for the founders of the Royal Society in England and gave a boost to scientific work in many European countries. However, the cautionary words of Prior (1954) are much needed. 

Bacon had Christian influences in his life as he worked with Puritan colleagues and his mother was known as a Puritan. However, he did not justify his "Man of Science" using Christian arguments. He secularised everything. Prior continues:  This compartmentalisation of knowledge is the same, in essence, as the double revelation approach adopted by Aquinas and Galileo before him. 

The same basic approach supported the development of Natural Theology in the 17th and 18th Centuries. Schaeffer sees this trend as a legacy from Aquinas: a consequence of his dividing knowledge into two autonomous realms. Writing in Escape from reason (1986), he says: 

The same autonomous principle has underpinned numerous supposed conflicts between the "Bible and Science", and has promoted the idea that biblical and natural truths are entirely complementary in character. 

The Baconian influence was significant for geology. The testimony of Humphrey Davy in 1805 is worthy of note. (Davy not only made important discoveries in chemistry, he also was a popular lecturer on many themes - including geology). 

A contemporary testimony to the impact of Bacon's philosophy comes from Marston and Forster (1989):  It is suggested later in this paper that the divergence of views about origins affecting Bible-believing Christians can be traced to the acceptance or rejection of the basic concepts of the Baconian "two books" approach. 

Geology and the "Two Books"

This general interpretation of intellectual trends can now be applied specifically to the development of geological thought. Two strands of understanding need to be identified: the recognition that the rocks forming the Earth's crust contain a geological history, and the association of geologic processes with certain timescales. 

The science of geology did not progress under the Greeks, although considerable expertise developed in pre-scientific times related to the mining of useful materials such as metallic ores. Early geological thinking was stimulated and heavily influenced by biblical history. Humphrey Davy was a very popular lecturer in matters of science at the beginning of the nineteenth century, and the text of his 1805 lectures in geology (Ospovat, 1978) provide a useful outline of the various "systems" of geology that had been proposed up to that time. In what follows, Davy is not followed in every detail, but he does provide the framework for analysis. 

Thomas Burnet's Sacred History of the Earth appeared in 1681. In this work, biblical history provides the context for the key events of geological history. Although Davy considered the book to be of low quality and "wholly unworthy of attention", Rudwick (1986) sees more substance in Burnet's writings and states that the book was "the prototype of a new kind of writing that became known as the "theory of the Earth"" (p.305). Contrast this with Davy, who said that it was Leibnitz who first "attempted a general system of geology". Leibnitz published his ideas in Protogea (1693) and discussed "the primary creation, the deluge, the changes that have been since produced and that will be produced in future ages. He assumes as the foundation of his reasoning the account of the creation given in the sacred writings ..." (Davy, p.30). Whiston is mentioned as someone who worked through in much more detail an idea that was considered in Protogea(that the Deluge was initiated by cometary impact). Whiston's A new theory of the Earth was published in 1696. Not discussed by Davy, but worthy of inclusion in this summary of theorists, is John Woodward who published his Essay towards a natural history of the Earth in 1695. His thesis was that the whole series of rock strata had its origins in the Noahic Flood, where the sequence of rock types and their enclosed fossils was determined by the specific gravity of the various solids. His posthumous publications on fossils have been regarded generally as an important contribution to early palaeontological science. 

Summarising this period, most of the pioneering work in geology was set in a Flood Geology context. Burnett's influential Sacred History of the Earth used the scenario of Creation/Fall/Flood to explain the features of the Earth observed today. Other studies of sedimentation and the significance of fossils were provided by writers who respected biblical history. Their various contributions did advance geological understanding - bearing in mind that these men must be assessed according to the state of knowledge at that time, and recognising that none of them had a coherent Christian methodology for their academic work. For these scholars, timescales were short because geologic processes associated with a global flood must be necessarily catastrophic. 

The next key theorist was Buffon, who published Histoire et thèorie de la terre in 1749 and Èpoques de la nature in 1779. This man broke with short timescales completely and proposed that the Earth was produced initially by a comet impacting on the sun. 

de Maillet wrote a book with the rather egocentric title of Telliamed; it was printed in 1748 and translated into English in 1750. This work sought to explain all observations by natural causes, without reference to God. Long timescales were an integral part of his system. John Whitehurst (1778) addressed geochemical problems and was primarily concerned with mineralogy. He seems to have been more sympathetic to creation and the Flood, but this was not a prominent part of his system. His style of reasoning was to work with general physical principles which he then applied to observational data. De Luc (1779) revived a more open biblical framework, setting his ideas in the context of creation and the Deluge. Indeed, he set out to reconcile Genesis and geology. He held an early version of the Day-Age theory - indicating that he was sympathetic to the idea that Creation Week extended over long periods of time. Wallerius is discussed briefly as someone with ideas close to de Luc and also Whitehurst. 

Finally, Davy turns to the plutonist/neptunist controversy which was a live issue in his own day. James Hutton championed the plutonist cause but, more importantly for this analysis, broke completely with referencing Scriptural history. This was because he was a philosophical empiricist (Tyler, 1989). He suggested that the geological processes operating today, together with the passing of sufficient time, provide adequate causes for all the geological features observable on Earth. Davy says: "Few works have ever excited more attention; few works have ever been more warmly admired, or more vehemently attacked ..." (p.47). The neptunist flag was held by Abraham Werner, who considered that "all the existing substances composing the globe were in a state of solution by the aqueous fluid... The rocks that are called primordial or primitive and that contain no organic remains, he supposes [to be] the first to have been deposited from the original aqueous solution... " (Davy, p.48). These materials were subsequently disaggregated and redeposited to for a sequence of transitional rocks, after which the earth was inhabited by plants and animals. During this period, the secondary strata were laid down, whereby solid particles came out of suspension in the oceans and covered the organic remains to preserve them as fossils. The details and outcome of this particular controversy has often been discussed (Hallam, 1983; Goodman and Russell, 1991) and will not be considered further here. 

Summarising these developments in the eighteenth century, the "two books" approach was becoming dominant and geology became increasingly divorced from biblical revelation. According to Moore (1968) "... the Baconian compromise became a convention in English-speaking scholarship for more than two hundred years: the basis for congenial relations between naturalists and exegetes ..." (p.323). The Enlightenment brought the impact of empiricist philosophy to the scholarly world, together with a conscious rejection of revelation as a foundation for knowledge. James Hutton is spoken of as the "Father of Geology" primarily because he was the first to articulate systematically this new worldview. 

However, it should be recognised that, for all the advocates of the various systems, it was not the data of geology that led to the acceptance of long timescales, but the philosophical presuppositions of the scholar which governed the interpretation placed on that data. 

Some geologists still recognised catastrophic processes at work in the rock record and developed geological histories punctuated by catastrophes. However, Biblical history was rarely, if ever, mentioned in their writings. The 19th century "catastrophists" held to a multiple catastrophe model of Earth history, of which the Genesis Flood was the most recent (leaving relatively insignificant surficial deposits referred to as the "Diluvium"). These held their own against the new "Uniformitarians" represented by Hutton, until Charles Lyell captured the minds of the geologic community by insisting that Hutton's methodology was the only permissible scientific approach to the study of the Earth. The Lyellian paradigm has reigned over geological thinking for over 150 years, and is only now being dismantled. 

Flood geologists have responded to these developments in different ways, but usually from positions of weakness because opportunities for Diluvialists to develop a career and participate in the academic world have been few. A deficiency apparent in their 19th and 20th century apologetic position has been a general neglect of the evidences for a geological history recorded in the rocks - something which a greater awareness of the geological debates in the 18th and 19th centuries would help to remedy. Evidences for catastrophism have been presented by contemporary diluvialists which have led to claims that the fossiliferous rocks as a whole were formed during the Flood year. Whilst this has convinced some, many others have felt that this scenario does not do justice to the evidences for a more sophisticated picture of successive geologic events. 


From these historical perspectives, it is concluded:
(a) that Flood geology models must be sought which do justice to the evidences for a significant geologic history;
(b) that most of the arguments for long timescales are paradigm-driven rather than scientific;
(c) that a thoroughly Christian worldview is crucial to the development of a more reliable understanding of geologic evidences, and this will require the abandonment of the "double revelation" approach to knowledge. 

It is suggested that whilst conclusions (a) and (b) are of direct relevance to Bible-believing students of geology, conclusion (c) is relevant to all Christians concerned about the scientific enterprise. What is to be made of statements like this from Marston and Forster (1989)? 

They are right that the Baconian approach has been enormously influential, but if the thesis of this paper is correct, and the Baconian approach does not represent a robust methodology for scholarly Christian work, an urgent need for reformation lies before us. 


Goodman, D. and Russell, C.A. (eds). 1991. The rise of scientific Europe 1500 - 1800. Sevenoaks: Hodder & Stoughton Ltd. 

Grant, E. 1986. Science and theology in the Middle Ages. In: Lindberg, D.C. and Numbers, R.L. (eds). God and nature. Berkeley: University of California Press. 49-75. 

Hallam, A. 1983. Great geological controversies. Oxford: Oxford University Press. 

Marston, P.V. and Forster, R. 1989. Reason and Faith. Eastbourne: Monarch. 

Moore, J.R. 1986. Geologists and interpreters of Genesis in the nineteenth century. In: Lindberg, D.C. and Numbers, R.L. (eds). God and nature.Berkeley: University of California Press. 322- 350. 

Ospovat, A.M. 1978. Four hitherto unpublished geological lectures given by Sir Humphrey Davy in 1805 from manuscripts belonging to the Royal Society of Cornwall with introduction and notes by Alexander M. Ospovat.Penzance: The Royal Geological Society of Cornwall. 

Prior, M.E. 1954. Bacon's Man of Science. Journal of the History of Ideas. XV. 

Rudwick, M.J.S. 1986. The shape and meaning of earth history. In: Lindberg, D.C. and Numbers, R.L. (eds). God and nature. Berkeley: University of California Press. 296-321. 

Schaeffer, F.A. 1968. Escape from Reason. London: Inter- varsity Fellowship. 

Schaeffer, F.A. 1968. The God who is there. London: Hodder & Stoughton Ltd. 

Shea, W.R. 1986. Galileo and the church. In: Lindberg, D.C. and Numbers, R.L. (eds). God and nature. Berkeley: University of California Press. 114-135. 

Tyler, D.J. 1989. Religious presuppositions in historical geology. Origins.3(7), 13-16. 

Westman, R.S. 1986. The Copernicans and the churches. In: Lindberg, D.C. and Numbers, R.L. (eds). God and nature. Berkeley: University of California Press. 76-113. 

This paper was first presented to the 6th European Creationist Congress, Amersfoort, The Netherlands, in August 1995)

It is the intention to develop sections of this paper in more detailed articles:
Tyler, D.J. 1996. The impact of the Copernican Revolution on biblical interpretation. Origins, (21), 2-8.
Tyler, D.J. 1997. The "double revelation" approach to knowledge: Aquinas, Galileo and Descartes. Origins, (23), in press. 

Return to top of page