Isaac Newton and Galileo Galilei were both scientists who pondered the use of reasoning in both science and religion. Despite the similarity of their fields, these men had different opinions about the role of scientific reasoning in religion. This can be seen in Newton’s appliance of the inductive reasoning he used in science to the question of God as opposed to Galileo’s strict belief that science and religion should be separated. Both men, however, acknowledged the importance of viewing science through the lens of actual evidence and sense experience without letting biblical texts get in the way.

Newton’s “System of the World” begins by stating laws of reasoning in nature: that scientists should “admit no more causes of natural things than such as are both true and sufficient to explain their appearance” and “certainly not relinquish the evidence of experiments for the sake of dreams and vain fictions of our own devising” (Newton 270). These ideas of reasoning are based on the thought that truths can be determined through sense experience and rational study, and that these truths cannot be overridden by abstract ideas of God and the earth that have no proof. Newton’s use of scientific reasoning to explain the natural world is quite similar to that of Galileo, but Newton also tries to use this reasoning on religious issues.

Newton begins his religious argument by using his scientific reasoning: “It is the dominion of a spiritual being which constitutes a God: a true, supreme or imaginary dominion makes a true, supreme, or imaginary God. And from his true dominion it follows that the true God is a living, intelligent and powerful Being; and from his other perfections, that he is supreme, or most perfect” (Newton 370). By applying his logic attained by studying the natural world to that of a religious issue, Newton bypasses the standard use of solely biblical texts to support the idea of God. Newton’s argument for religious ideals is not perfect, but it is a scientist’s argument, using what he can of scientific reasoning in religious matters. In this way, Newton joins two often opposing areas of thought by using science to prove religion without forcing the limitations of religion on scientific discoveries.

Galileo did not directly state his beliefs about God or religion, but did pronounce that religious reasoning was wrong for use in matters of science. He argues in his 1615 letter to the Grand Duchess of Tuscany that most people merely read the Catholic Bible and based their opinions off of Scripture that they misunderstood. As he saw it, academic philosophers were trying to disprove things that were obvious to the senses with “passages taken from places in the Bible which they had failed to understand properly, and which were ill-suited to their purposes” (Galilei 1). Galileo writes that people were reading complex biblical texts incorrectly and not the way they were meant to be read.

The intrusion of religious authorities on matters of science seemed foolish to Galileo, as he based his scientific reasoning off of “sense experiences and very exact observations,” as Copernicus did, allowing that his new theories about astronomy had no effect whatsoever on religious ideals (Galilei 2). The salvation of souls was not altered by the idea that the earth was in motion, and Galileo also argues that sense experiences should not be condemned by “the testimony of biblical passages which may have some different meaning beneath their words” (Galilei 3). In this way, though Galileo is asking for a separation of religious authority and scientific reasoning, he is also calling for a more intellectual reading of the Catholic Bible. Galileo’s call for the intellectual reading of religious texts on many levels was first suggested by Baruch Spinoza, and started to have more importance as science and religious ideals began to collide.

Galileo Galilei held the opinion that science and religion should be separated and that religious texts should not override sense experiences. In this way, he is defending scientific reasoning over commonly accepted religious authority. Galileo wanted the separation of science and religion not because it was a bad thing, but because religious texts were not yet read on many levels and were used to disprove obvious characteristics of the natural world. Newton also stated the importance of scientific reasoning, and even used it to prove the existence of God. Both scientists seem to stress the idea of using observation and experiences to understand the natural world as well as using this intellectual reasoning to support religious viewpoints. In effect, Galileo acknowledged the difference between scientific and religious reasoning, expressing a hope that scientific reasoning be applied to religion, whereas Newton actually applied this scientific logic to a religious question.