Religion and Science

The history of the science-religion debate is often told by means of two famous test cases: the Italian mathematician Galileo Galilei (1564–1642) and his interaction with the Roman Catholic Church, and the English naturalist Charles Darwin (1809–1882), whose ideas led to controversies with various (mainly Protestant) theologians. Two cases do not make a history, and John Brooke's work has shown how diverse and particular are the interactions of different sciences with different patterns of religious thought. However, the two cases are highly significant.

Galileo made advances in many areas of mathematics, science, and technology. He is most famous for his adoption of a sun-centered model of the solar system at a time when the church taught that the Earth was the center of the universe. His defense of the sun-centered model, first developed by Copernicus (1473–1543), led ultimately to Galileo being placed under house arrest by the Catholic Church. It is important to recognize, however, that the church was not separate from science but a great sponsor of scientific exploration, and that Galileo was himself a believer and cared passionately about the interpretation of Scripture as well as about the truths of physics. Political and personal tensions played a large part in his denunciation.

The "Galileo affair," then, was not a simple case of the church suppressing free enquiry by a devoted scientist. Galileo's significance is somewhat different. First, in retrospect religious authorities could see that prevailing theories of the cosmos might undergo gradual change and that this process was one they could not control. Second, Galileo's thought set the tone for the development of physical science from that point. He saw that science would be most effective if it concentrated on measurable quantities and reproducible effects; he also saw that observations of a ball sliding down a slope—a testable, quantifiable system—could be applied to more remote problems such as planetary orbits. Galileo's thought therefore anticipated the massively successful mechanics of Isaac Newton (1642–1727) and the impression Newton's work gave of a mechanical universe, resembling a giant clock. In such a picture of the cosmos, the role of a deity might be restricted (though Newton would not himself have accepted this) to that of the maker and initial winder of the clock.

The thought of Galileo therefore helped to shape not only the particular sciences he studied but the whole scientific method. Modern science has focused very effectively on the reproducible and measurable and on understanding complex systems through simple models. It has rigorously avoided explanations involving a creator with purposes for the creation. However, the sciences do rest on faith commitments. Particularly important is the belief that the universe is ordered and consistent, such that the same laws operate in complex systems remote in time or space from the experimenter—in the center, for example, of a distant star—as operate in model systems.

It has often been argued that the Christian thought-world was particularly propitious to the development of this faith commitment because that thought-world not only emphasized the cosmos as a rational place, created by God through rational commands, but also stressed the distinction between God and the world. A strong motivation among many of those who developed the natural sciences was the desire to investigate the world to see how the creator had designed it. This exploration of "natural theology" went hand in hand with the development of physics and chemistry, especially in England between 1650 and 1800. But the exploration was only made conceivable by the conviction that the world was not in itself sacred. The relationship between physical science and Christian theology (at least in England) in the second half of the seventeenth century has been described as "almost a rapturous love affair." However, the success and reach of the sciences grew in parallel with developments in Enlightenment thought that enabled thinkers to question the authority of traditional religious teaching. Moreover, previously unexplained phenomena that had been considered "acts of God" turned out to obey scientific laws. Where God's activity had been inserted to plug a "gap" in scientific accounts, gap after gap tended to close, and those studying the clock-worklike Newtonian universe found it easier and easier to dispense with talk of the clock maker. Those who resisted this mechanistic worldview, such as proponents of Naturphilosophie in Germany, tended to part company with mainstream scientific thought.

In a sense, the process by which theological explanations lost their authority and their partnership with scientific theories reached its climax in the disputes over the thought of Charles Darwin. Very careful observations of the natural world, coupled with consideration of artificial breeding methods and restrictions on population sizes, had led Darwin to his theory of evolution by natural selection: variations occurred at random in biological organisms, and environmental pressures and competition with other organisms "selected" the variants that survived to reproduce themselves. As in the case of Galileo, theologians and scientists alike were divided as to the correctness of these new proposals. Many theologians celebrated Darwin's theory of "descent with modification" as a sign of God making a world that could make itself. Others resisted Darwinism on the grounds that it eliminated the need for a divine role in the design of individual creatures, and by implication also abolished the distinctiveness of human beings. Evolutionary theory seems to dispense with the need for any sort of "watchmaker," any sort of rational designer to design the mechanisms of living things. These nineteenth-century Darwinian controversies shaped not only the course but also the nature of modern science because they aided the shift away from the "gentleman amateur" scientist (often a clergyman) to the professionalized model we know today.