Natural Science and Supernatural Thought Experiments
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religions Article Natural Science and Supernatural Thought Experiments James Robert Brown Department of Philosophy, University of Toronto, Toronto, ON M5R 2M8, Canada; [email protected] Received: 9 May 2019; Accepted: 11 June 2019; Published: 18 June 2019 Abstract: Religious notions have long played a role in epistemology. Theological thought experiments, in particular, have been effective in a wide range of situations in the sciences. Some of these are merely picturesque, others have been heuristically important, and still others, as I will argue, have played a role that could be called essential. I will illustrate the difference between heuristic and essential with two examples. One of these stems from the Newton–Leibniz debate over the nature of space and time; the other is a thought experiment of my own constructed with the aim of making a case for a more liberal view of evidence in mathematics. Keywords: thought experiment; God; Newton–Leibniz; mathematical methods There is a long tradition of using religious notions in science. Einstein famously said that God does not play dice. Bohr countered with the remark that not only does God play dice but he also tosses them where they can’t be seen. These, respectively, are picturesque ways of rejecting or embracing indeterminism in physics. God is a convenient metaphor, but is in no way essential to making Einstein’s or Bohr’s respective points. This is a rather trivial use of God in science. We get a little more serious when we encounter phrases such as “a god’s eye point of view”. In this case there is the suggestion of the existence of a fact of the matter that an omniscient being would grasp, even if we humans were not capable. It can help advance a philosophical debate in one direction or another, and even atheists find the metaphor useful in debate. On the other hand, theological notions are sometimes invoked only to be mocked. The question “How many angles can dance on the head of a pin?” is taken to be the height of folly. The targets of derision were medieval scholastics, even though it turns out that as a matter of historical fact they did not entertain the issue. Thought experiments involving God often aim at telling us something new about God. Other thought experiments involving God have a different aim: They use the idea of God to tell us something new about the world. What follows is an instance (actually two instances), of the latter. In other words, God is not the end but rather is a means to the end. I am going to discuss two thought experiments where God plays an important or even crucial function. The first of these is the thought experiment (or cluster of thought experiments) that played a role in the Newton–Leibniz debate on the nature of space and time. The second is a thought experiment of my own concerning the nature of legitimate mathematical methodology. Though both are effective in achieving their goals, they turn out to function in interestingly different ways. In his Principia, Isaac Newton claimed “Absolute, true, and mathematical time, in and of itself and of its own nature, without reference to anything external, flows uniformly and by another name is called duration. Relative, apparent, and common time is any sensible and external measure (precise or imprecise) of duration by means of motion; such a measure—for example, an hour, a day, a month, a year—is commonly used instead of true time.” (Newton 1999, p. 408). Religions 2019, 10, 389; doi:10.3390/rel10060389 www.mdpi.com/journal/religions Religions 2019, 10, 389 2 of 9 Religions 2019, 10, x FOR PEER REVIEW 2 of 9 The claim about the nature of time was followed by a similar claim about the nature of space: “Absolute“Absolute space, space, of itsof ownits natureown nature without without reference re toference anything to external,anything always external, remains always homogeneous remains andhomogeneous immovable. and Relative immovable. space Relative is any movable space is any measure movable or dimension measure or of dimens this absoluteion of this space; absolute such aspace; measure such or a dimensionmeasure or isdimension determined is determined by our senses by fromour senses the situation from the of situation the space of with the space respect with to bodiesrespect and to bodies is popularly and is usedpopularly for immovable used for immovable space, as in space, the case as ofin spacethe case under of space the earth under or inthe the earth air or inin thethe heavens,air or in wherethe heavens, the dimension where the is determineddimension is from determined the situation from of the the situation space with of respectthe space to thewith earth.” respect (Newton to the earth. 1999”, p.(Newton 408f). 1999, p. 408f). What Newton called “absolute space and time” is now more adequately called “substantivalism”, meaning that time and space are things in their own right, not dependent on anything else. The picture Newton paintedpainted is is that that space space and and time time exist exist independently independently from everythingfrom everything else (except else God,(except perhaps). God, Itperhaps). has nothing It has to nothing do with to the do bodies with the that bodies might that or mightmight notor might be in spacenot be or in thespace events or the that events might that or might notor might happen not in happen time; nor in hastime; it nor anything has it toan doything with to how do wewith measure how we and measure observe and space observe and time,space and and so time, on. Theyand so are, on. according They are, to according Newton, “God’sto Newton, sensorium”, “God’s sensorium”, which is something which is of something a mystery. Newtonof a mystery. thought Newton of creation thought as God of placing creation matter as God at particular placing locationsmatter at in particular an otherwise locations empty spacein an andotherwise this act empty of creation space happenedand this act at of a particularcreation happened time. at a particular time. Newton oofferedffered his his famous famous bucket bucket thought thought experiment experiment as the as justification the justification for his belieffor his in belief absolute in space.absolute We space. cannot We detect cannot our detect location our inlocation absolute in absolute space, nor space, can wenor detectcan we our detect absolute our absolute velocity throughvelocity through space. Moreover, space. Moreover, we cannot we detectcannot our detect location our location in absolute in absolute time. We time. can, We however, can, however, detect absolutedetect absolute accelerations. accelerations. It is, in It fact, is, in an fact, everyday an everyday experience experience which youwhich can you feel can when feel driving when arounddriving aaround corner. a corner. This cannot This cannot be reduced be reduced to relative to relative acceleration. acceleration. Imagine Imagine two two cars cars facing facingin in oppositeopposite directions, initiallyinitially stationarystationary withwith respectrespect toto oneone another.another. TheyThey might start to move apart, gaining in relativerelative velocity;velocity; they are accelerating relative to one another. So far the situation situation seems seems symmetrical. symmetrical. However, thethe passengerspassengers insideinside couldcould noticenotice aa didifffference.erence. In one car the passengers feel thrown back inin theirtheir seats,seats, whilewhile thethe othersothers feelfeel nono suchsuch force.force. TheThe formerformer isis thethe oneone thatthat isis undergoingundergoing genuinegenuine absolute acceleration. The bucketbucket experimentexperiment (Figure (Figure1) 1) is designedis designed to showto show that that absolute absolute acceleration acceleration is detectable. is detectable. We haveWe have three three cases cases to consider to consider in this in experiment this experiment (which (which could becould either bea either real experiment a real experiment or a thought or a experiment).thought experiment). In stage IIn the stage bucket I the and bucket the water and the are atwa restter withare at respect rest with to onerespect another. to one In another. stage II the In bucketstage II is the turning bucket relative is turning to the relative water. to In the stage water. III the In bucket stage andIII the water bucket are againand water at rest are with again respect at rest to onewith another. respect to We one need another. to explain We need the di tofference explain between the difference stage I between where the stage surface I where of the the water surface is flat of andthe water stage IIIis flat where and the stage surface III where is concave. the surface Notice is co thatncave. we cannot Notice do that it bywe appealcannot todo relative it by appeal motion, to sincerelative there motion, is no relativesince there motion is no of relative water tomotion bucket of in water either to stage bucket I or in III. either stage I or III. Figure 1. Newton’s bucket thought experiment. Figure 1. Newton’s bucket thought experiment. Newton’s answer is this: In stage III (but not in I) the water and bucket are in absolute motion; they Newton’s answer is this: In stage III (but not in I) the water and bucket are in absolute motion; are rotating in absolute space. The crucial claim that Newton makes is that the best explanation—perhaps they are rotating in absolute space. The crucial claim that Newton makes is that the best explanation— the only explanation—is absolute space. The water-bucket system is rotating with respect to space perhaps the only explanation—is absolute space. The water-bucket system is rotating with respect to itself. Therefore, space exists (as a thing in its own right). space itself. Therefore, space exists (as a thing in its own right).