BELIEFS AND PHYSICS:

Howdo metaphysical beliefs and physics interact? To formulate some answers to this question, we need to lookat actual examples. Here weconsider some of the earliest information we have on mankind seekingsystematic understanding of our physical environment. Work of this sort may have been done inprevious civilizations, but the first records we have come from theGreeks, beginning with Thales of Miletus shortly after 600 BC. We will carry our survey down toAristotle in the fourth century BC, the first to attempt a comprehensivephysics.

Fromour perspective at the end of the twentieth century, the physics of theseearly scientist-philosophers seems crude, rash, and often absurd. Yet scientists only 200 years from nowmay well think the same of our physics. Let us, then, try to give each ancient thinker a sympathetic reading,seeking to understand what forces led to each proposal, and howphysical observation and research affected metaphysical views and viceversa.

Thereare some advantages in picking examples from so long ago, in spite ofdifficulties with historical sources. These early researchers first proposed a number of fundamentalproblems which have not been solved to this day. Yet we have advanced enough to see a good deal further alongthe road than they could. We can,perhaps, assess the fruit of their labors better than we can those of morerecent physicists.

ThePhysical Substratum

Howdo we explain the nature of the material world which we observe? This question was apparently first answeredin physical rather than supernatural terms by Thales of Miletus, a practicalthinker reputed to have made contributions to law, politics, civilengineering, mathematics, and astronomy; he was even credited with successfullypredicting an eclipse of the sun in 585 BC (Nahm, 1964, pp. 32-33;Farrington, 1949, p. 31).[1]Thales proposed that there was a single basic substance behind all thediverse phenomena we experience.[2] His rather tangible choice forthis substance was water. Thalesnot only thought water was the substance on which the earth actually floated(Aristotle, 325BCb, 2.13 [294a]),[3]but also that it was the basis of all other materials. Aristotle (325BCa, 1.3 [983b]) suggestshe made this proposal because of the obvious necessity of moisture forlife. Nahm (1964, p. 33) thinksperhaps it was because Thales knew that water could assume the three formsC solid, liquid and vapor.

Thales’preference for natural causation, Farrington (1949, pp. 29-31) suggests,came from observing various agricultural and industrialtechniques. He felt free toadvocate this openly because of the relative intellectual freedom in Melitus, acity ruled at that time by merchants rather than a military or priestlycaste. Though preferring naturalcauses, Thales does not appear to have been an atheist. Arisotle (325BCc, 1.5 [411a]) says hethought ‘that all things are full of gods.’ Perhaps he realized that technological processes depend onthe natural attributes of the substances they manipulate, and thisled him to extend the idea to processes operating in nature. The proposal turned out to be afruitful one.

Anaximander(fl 555 BC)[4] followedThales at Miletus, and was considered his student and successor (Theophrastus,320BCb, 476). He also followedThales’ belief in a single natural universal substance, but rejected hischoice, water. Aristotle (325BCd,3.5 [204b]; see also Lloyd [1970], p. 20) suggests he did this because he couldnot see water as the source of fire, since their characteristics (cold andwet vs. hot and dry) were mutually destructive. Anaximander proposed an abstract substance unlikeanything observed, which he called apeiron, meaning something like ‘unlimited,’ ‘boundless,’ or ‘infinite.’ This basic substance contained allthe opposites, and formed such secondary substances as fire and water by separation(Aristotle, 325BCd, 3.5 [204b]; Simplicius, 530ADb, 32r). These secondary substances had theirorigin in the apeironand returned to it when they were destroyed.

Anaximenes(fl 535) was a third Milesian to investigate the basic constitution ofmatter. He too favored a singleultimate substance, but turned to an observable material, air, for hischoice. Perhaps he felt his predecessor'sapeiron was too farremoved from observation.[5] Anaximenes explained the diverseobserved materials as various manifestations of air. When rarefied, air becomes fire; condensed,it forms successively wind, cloud, water, earth, and stone as the degreeof condensation increases (Hippolytus, 236AD, 1.6).

Thecosmologies the Milesians proposed were based on their physics. Thales had his earth floating onwater. Anaximander formed thecold earth and fiery heavens by separation from the apeiron (Plutarch, 100ADb, 2). Anaximenes floated his earth onair, and employed the wind to push his stars around (Hippolytus, 236AD, 1.6).

The history of Milesian views about theprimary substance is chiefly remarkable for the way in which the awarenessof the problems grew from one philosopher to the next. . . . As is usual in the history of science,their actual theories strike a later age as childish Cthey already appeared so to Aristotle. But the measure of their achievement is the advance they made ingrasping the problems. Theyrejected supernatural causation and appreciated that naturalistic explanationscan and should be given of a wide range of phenomena: and they took the first tentative steps towards anunderstanding of the problem of change (Lloyd, 1970, pp 22-23).

AMathematical Substratum

Adifferent approach to the question of what underlies the physical world wasproposed by Pythagoras (fl 525), or possibly by one of his followers, thePythagoreans. Having observed thatharmonious sounds are produced by vibrating strings whose lengths havesimple ratios, he proposed that reality consists of numbers (Aristotle,325BCa, 13.6 [1080b], 14.3 [1090a]). Though the Pythagoreans apparently understood this in a rather crudelyliteral sense, their suggestion led to increasing interest in the formrather than the substance of matter. This suggestion also proved fruitful for research from antiquityonward, turning the attention of physicists and astronomers tonumerical measurement and mathematical modeling. It led to substantial advances inknowledge among the Pythagorean astronomers. Unfortunately, it also produced a great deal of ‘mumbo-jumboand crude number-mysticism’ (Lloyd, 1970, p. 27).

Plato(428-347) was influenced by the Pythagoreans, and counted knowledge of geometrya necessity for admission to his Academy. He observed that geometric drawings are at best only a roughapproximation to the ideas that lie behind them. For example, a true tangent meets its circle at one pointonly, but it is impossible to draw this. Plato apparently extrapolated this observation to reality ingeneral, coming to the conclusion that ultimate reality consists of eternal,unchanging ideas, which are only imperfectly represented in the changingworld of objects observable by our senses. True knowledge is knowledge of these eternal ideas ratherthan of unreliable sensory data. The results are described by Clagett (1963, p. 84):

We do not have to wait until medieval orearly modern times for the application of geometry to the investigation ofnature, for it began in both physics and astronomy in the fourth century[BC] and matured in the Hellenistic and Greco-Roman periods. We have already suggested the basicimportance of the Pythagorean mathematical point of view of nature; butwhen the mathematical view was coupled with something close to scorn of theworld of the senses, as it was in some of the Platonic dialogues, little soundphysics could arise. Even the mostapologetic Platonist will not stand behind Plato's Timaeus as a work of high scientific caliber,although it is true that some of the ideas suggested therein were notwithout their influence on Aristotle and later authors.

Motionand Vacuum

Meanwhile,the question of how motion could be reconciled with the idea of a single,universal substance was being considered by Parmenides (fl 480). He came to the rather startlingconclusion that it couldn’t. Parmenides believed the single universal substance to be being itself. A vacuum was thus non-being, which by definition could not exist. Therefore all space was filled with thesingle, ultimate substance which could not change without beingnon-ultimate and which had no room to move (Parmenides, 480BCb). Rather than accepting thetestimony of human senses as indicating something must be wrong withhis argument, Parmenides chose instead to believe that our senses arein error! (Parmenides, 480BCa). Parmenides’ follower Zeno (fl 445) constructed several exceedinglyclever arguments to prove that motion did not exist. These arguments were frequently ignored but not successfullyrefuted until the invention of calculus some 2000 years later.

Onesolution to the quandary posed by Parmenides was to adopt a pluralisticworldview rather than his monistic one C that there are several basic substancesrather than only one. In thiscase, motion could take place as the different substances slipped by or mixedwith one another, even if there was no vacuum to provide extra room to moveabout in. Empedocles (fl 445)adopted this approach, proposing that there were four elements instead ofonly one, namely earth, water, air and fire. All material things were a mixture of these, and change tookplace when the composition of various mixtures changed. The cause of such change Empedoclestook to be two forces, which he called Love and Strife (we would call themattraction and repulsion). Thismodel, as developed further by Plato and Aristotle, was to be the dominantview in physics through the rest of antiquity until modern times (Clagett,1963, p. 84).

Anaxagoras(fl 445) carried the pluralistic idea to an extreme by postulating theexistence of an infinite number of different sorts of things C‘seeds,’ or ‘germs,’ he called them C which are infinitely small and eternal. Every existing thing is a mixtureof these, so that when a human eats fruit (say), the body does not make fleshand bone out of some other substance, but it extracts the flesh and bone particlesfrom the food (Anaxagoras, 445BC; Aristotle, 325BCd, 1.4 [187a-b]). Anaxagoras’ influence does not appearto have been great, as he was going against the preferred tendency to explainthe diversity of phenomena by as few items as possible. Occam’s razor was already in use longbefore Occam was born!

Theresponse to Parmenides which most neatly solved the problem he raised was theatomic theory, proposed by Leucippus (fl 435), developed by Democritus (fl410) (Simplicius, 530ADb, 28.15; Hippolytus, 236AD, 1.10-11), andstill further by Epicurus (341-270) (Aëtius, 100AD, 1.3.18; Cicero,43BCa, 1.26.73). Reality,said the Atomists, consists of an eternally-existing, universalsubstance, but this occurs as an infinite number of unchangeable,invisibly small particles, called ‘atoms’ (indivisible) because theycould not be cut into smaller pieces. The atoms were separated from one another by a void or vacuum, sothat motion was possible, and in fact, continual (Aristotle, 325BCd, 8.9[265b]; Cicero, 43BCb, 1.6.17).

UnlikeAnaxagoras’ seeds, atoms were all of the same substance, but differedin size and shape. They formed thevarious objects of our experience by collision and entanglement Cthe origin of a particular material occurring when the atoms cametogether, its destruction when the atoms separated. Thus change was real and didn’t need tobe explained away as an illusion. On the other hand, sensory characteristics themselves were due to theshapes and combinations of the atoms, not to real colors and tastes in theatoms. Democritus speculatedelaborately on the nature of sensory experience, and on how suchcharacteristics as hardness and softness, lightness and heaviness, were producedin various objects (Simplicius, 530ADa, 293.33; Plutarch, 100ADa, 8;Theophrastus, 320BCa, 6.1.6; Theophrastus, 320BCc, 49-82). Surprisingly, Democritus, too,felt rational thought was more reliable than observation (SextusEmpiricus, 200BC, 7.138).

Theancient atomic theory never achieved dominance in antiquity like the modernatomic theory has. It ascribed theorigin of the world to chance rather than intelligence, and it had nothingbeyond necessity to explain large-scale organization within the world(Aristotle, 325BCd, 2.4 [196a-b]; Eusebius, 340AD, 14.27.4-5).[6]

ThePhysics of Aristotle

Bythe time of Aristotle (382-322), Greek astronomy had progressed to the pointthat astronomical objects were obviously much larger and further away thanmeteorological phenomena (Lloyd, 1970, p. 110; Farrington, 1949, pp.99-100). Heraclides of Pontus’ (fl330) proposal, that the daily movement of the sun, moon and stars was actuallydue to the earth’s rotation, may have come too late to influence Aristotle; itdid not meet with acceptance in any case (Clagett, 1963, p. 114; Sarton, 1964,pp. 506-08; Lloyd, 1970, pp. 94-97). Without telescopes, changes in the sky were not obvious beyond the moon,so it is not surprising that Aristotle proposed a two-realm version ofphysics. (1) Above the moonwas a supralunar realm without change, where all motion was eternal andcircular, following the scheme of Eudoxus (fl 365). (2) Below the moon was the sublunar realm of change,characterized by natural vertical motion as each of the four elements soughtits own level (Clagett, 1963, pp. 84-87; Lloyd, 1970, pp. 109-10). Aristotle modified the four-elementscheme of Empedocles by allowing the elements to be transformed fromone into another, and by adding a fifth element, aether, from which the supralunar realm wasconstructed (Clagett, 1963, pp. 85, 87; Lloyd, 1970, pp. 108-11).

Aristotlealso proposed four kinds of causation: (1) a material cause (like that of theMilesians), what something was made of; (2) a formal cause (like that of thePythagoreans and Plato), how something was structured; (3) an efficientcause (like that of Empedocles), what forces produced it; and (4) a finalcause, for what purpose the object was made (Farrington, 1949, pp. 123-24;Clagett, 1963, pp. 84-85; Lloyd, 1970, pp. 105-06).

Aristotle’sphysics and causation continued to have influence through antiquity andthe medieval period until modern times, as they appeared to provide bothconsistency and believable explanations for the observed natural order(Clagett, 1963, p. 84; Lloyd, 1970, pp. 99, 122).

InteractionsBetween Metaphysics and Physics

Wemust now consider what we have learned about how metaphysical beliefs andphysics interact.

Howwere physical concepts used to develop and evaluate metaphysical beliefs?

Thetechniques of craftsmen may have suggested naturalistic explanationsfor physical phenomena to Thales and his followers.

Thediscovery that harmonious sounds were produced when vibrating strings hadlengths in simple ratios may have led the Pythagoreans to postulate theidea that number is the ultimate feature of reality rather than matter.

Therealization that geometric drawings are at best only rough approximations tothe ideas that lie behind them apparently convinced Plato that ultimate realityconsisted of eternal ideas which are only imperfectly realized in physicalthings.

Reluctanceto abandon sensory evidence kept many from following Parmenides, proposinginstead various models of reality in which change and motion were real. These included the multi-elementschemes of Empedocles and Anaxagoras, and the Atomists’ introduction of avoid and breaking the ultimate substance into tiny pieces.

Astronomicalevidence that the heavenly bodies were at great distances was in partresponsible (together with Eudoxus’ scheme for reducing the heavenly motions tocircles) for Aristotle's distinction between the earthly realmof change and the changeless heavens.

Howwere metaphysical beliefs used to develop and evaluate physical concepts andtheories?

TheMilesians’ metaphysic of natural causation led to their suggesting variousnatural explanations for everyday phenomena which Greek mythology hadascribed to Zeus, Poseidon, or one of the other gods. It also led to speculation regardinga most basic substance. Thisresulted, on the one hand, in beginning attempts to study the basis of matter;on the other, it consistently produced (unwarranted) optimism that thenature of the substratum could be easily discerned.

ThePythagorean metaphysic of number as the basis of nature proved very fruitful insome fields, and certainly was important in introducing mathematics as a toolto understand reality. However, it also led to considerable number-speculation where thesubject of investigation was not hospitable to such an approach at that time.

Plato’sview that reality was in the eternal ideas, rather than in their imperfectrepresentations in nature, led him to devalue the use of observation andexperiment on physical objects in favor of purely abstract reasoning,disconnecting theory from observation.

Parmenides’view that motion was logically impossible led him to reject the contrarytestimony of the senses.

Democritus’view that reality could be completely described by atoms moving in the void ledhim to a number of striking insights, mixed with numerous unwarrantedspeculations. His stronglyreductionistic explanations ignored the possibility of higher levels of structureand of design in nature.

Theapparent completeness and consistency of Aristotle’s division of thecosmos into two realms with two types of physics had long-term (and largelynegative) effects on the practice of physics, which were not overcome until thelate middle ages.

Bythe time of Plato and Aristotle, widening class divisions in the Greekcity-states were discouraging the leisured class from involvement in hands-on,technical sorts of labor. Thisseems to have had a negative effect on any research which looked practical,leading to the devaluation of the sort of physical investigationswhich would later transform Western society in the centuries after the Reformation.

Howdo shared metaphysical beliefs of the physics/science community influenceits research agenda?

Therewere apparently no really organized physics or science communities atthe beginning of this era, but certainly the Milesians sought purelynatural explanations of phenomena. Though this encouraged experimentation and observation, itmade it difficult for them to explain the occurrence of order in nature.

ThePythagoreans were certainly a community, though more of a religiousfellowship than a scientific society. They concentrated on applying mathematics to their investigations,producing some impressive results where this was possible at the time(astronomy and acoustics), but rather fantastic number-mysticism elsewhere.

TheAcademy of Plato was mainly successful in its mathematical work, as theemphasis on reason rather than observation tended to produce abstract, logicalconstructions. Plato’sproposal that the movement of astronomical objects be explained by combinationsof circular motions both helped and hindered astronomical research. Plato's admission of eternal forms gavebetter explanations for order in nature than the merely material causationof the Milesians and Atomists.

Aristotle’sproposal of four types of causation (matter, structure, energy, andpurpose) made better sense of the observed order in nature. Together with a restoration of thevalue of observation, this led to some effective biological research in theLyceum of his time and later.

SomeLessons for Today

Cansuch a brief tour of ancient Greek physics teach us anything about how weshould view physics today? Ibelieve it can. Consider thefollowing questions in the light of our survey.

Givena hierarchical structure to reality, is there any reason to believe anempirically constructed ‘bottom up’ metaphysics will be anything more thanaccidentally correct before the ‘final physics’ is discovered?

AncientGreek science, though showing real progress, does not seem promising for thishope. Thales’ and Anaximenes’proposals that water and air are the ultimate substances seem especiallycrude to us, but they were based on certain observations. Anaximander’s more sophisticated ideaof an unspecified stuff behind appearances is an improvement, and itsought to solve the problem of contrary attributes. Anaximenes’ concept of condensationand rarefaction, presumably based on the conversion of water into ice andsteam, also marked a step forward. Aristotle’s version of Empedocles’ four-element theory (earth,water, air, fire), though returning to visible material as basic, at leastprovided for one element to change into another. In retrospect, none of these suggestions were close towhat we know to be the case today.

Eventhe ancient atomic theories, though a vast improvement with theirinvisible units of structure and space between them, were unable toexplain macroscopic attributes except by arbitrary guesswork. Throughout the period we see increasingsophistication, coupled with the incorporation of additional evidence,which eventually was revived in modern times as a new atomic theory. But modern investigation has found thatwhat we call atoms are composites of nucleons and electrons, and that nucleonsare probably composites of quarks. There is no way yet for us to tell if quarks, too, may not becomposite. We do not know how deepthe hierarchy is, nor whether anything lies beneath it.

Howdoes ‘Occam's Razor’ influence physics? Do we tend to jump to unwarranted conclusions about thecompleteness of very preliminary theories?

Though‘Occam's razor’ is a medieval term, it describes a common human tendency toconstruct the simplest theory consistent with the known evidence; clearly,it is valuable as a method of procedure. But the ancient Greeks had no idea how complicated nature might be,and tended to think they were only one layer away from the bottom. We can see they were mistaken,having penetrated several more layers. But what about our theories? Are we only a layer away from the bottom of things, or do we also jumpto conclusions when we ascribe to them an ultimacy they may not deserve?

Inthe area of kinematics, is it reasonable to believe nature can be limited to thethree spatial dimensions and one time dimension of modern relativity theory?

Thisis certainly the simplest model consistent with our current, empirical, ‘bottomup’ physics. But mathematicshas been worked out for larger dimensionalities; some of the recent ‘grandunification theories’ incorporate 11 or more dimensions; and certainfeatures of the occult and of the supernatural in Scripture point toa more complex situation. One’sworldview will have an influence on whether this is thought to bepossible or probable, and whether it might be worth pursuing as a researchstrategy.

Inthe area of dynamics, is it reasonable to believe that the four currently-knownforces are all that exist? Thatthey may be unified into a single superforce?

Itis certainly reasonable to believe these things in the sense that we know of noreason why they might not be true. The discussion above, however, should make us wary of too much confidencehere, since two of these forces (the strong and weak interactions) were onlydiscovered in the past century, and we have generally been poor prophets ofwhat advancing technology will turn up. The desire for unification and simplification hasoften been fruitful in research, but like Pythagoreanism, has equally often ledastray.

Inthe area of dynamics, is it reasonable to believe that knowing the ultimateparticles and physical forces will be sufficient to explain reality withoutrecourse to special initial or boundary conditions?

Withoutmaking use of special revelation, we do not know the answer to thisquestion. However, the ‘fine-tuning’in our universe, currently being discussed as the ‘anthropic principle,’suggests that planning rather than chance is the more basic characteristic ofreality.

Inthe area of dynamics, it is reasonable to believe that the universe is anautomaton (like a clock) that runs by itself C whether accidental or designed Cor may it be an instrument (like a guitar) that is designed for input?

Again,input from special revelation is helpful here, though it is currently viewed as‘more scientific’ to opt for a self-contained, closed universe.

Aftersome 2500 years of doing physics from inside our universe, we still don’t knowwhether there is an ultimate substratum, and if so, what it lookslike. We have progressedenough to be sure it is not water, air, or atoms C in either the ancient or modern sense ofthe word.

Thereis a strange resonance in reality between mathematics in the human mindand the structure of nature. Wedon't know enough to say how pervasive this structure is or how it is imposed.

Parmenidesand Zeno were certainly mistaken about the unreality of motion. If it finally turns out they were rightabout our senses being totally deceived, it will still have only been a luckyguess. The human sensory apparatusand its technological extensions have revealed an orderly world of much greatercomplexity than any of the ancients imagined.

Thereductionism of Democritus is still with us in a suitably updated form,but it faces some real challenges from design in nature. Aristotle was wrong about there beingtwo different kinds of physics for the terrestrial and astronomical realms. He might yet prove to be right for theearthly and the heavenly.

BIBLIOGRAPHY

Mostof the items herein are ancient works. For some of these, such as Aëtius and Sextus Empiricus, the dates givenare very approximate. For theother ancient works, the date given is the author's date of death or floruit. Dates before 1000 AD are marked AD or BC.

Aëtius. (100AD) Relicsof the Philosophers.

Anaxagoras. (445BC) Fragments.

Aristotle. (325BCa) Metaphysics.

Aristotle. (325BCb) Onthe Heavens.

Aristotle. (325BCc) Onthe Soul.

Aristotle. (325BCd) Physics.

Cicero. (43BCa) Onthe Nature of the Gods.

Cicero. (43BCb) Onthe Chief Good and Evil.

Clagett, Marshall. (1963) Greek Science in Antiquity. New York: Collier.

Empedocles. (445BC) Fragments.

Eusebius. (340AD) Preparationfor the Gospel.

Farrington, Benjamin. (1949) Greek Science I: Thales to Aristotle. Harmondsworth, Middlesex: Penguin.

Hippolytus. (236AD) Refutationof All Heresies.

Lloyd, G. E. R. (1970) EarlyGreek Science: Thales to Aristotle. New York: W. W. Norton.

Nahm, Milton C., ed. (1964) Selections from Early Greek Philosophy, 4th ed. Englewood Cliffs, NJ: Prentice-Hall.

Parmenides. (480BCa) The Way of Opinion.

Parmenides. (480BCb) TheWay of Truth.

Plutarch. (100ADa) AgainstColotes.

Plutarch. (100ADb) Miscellanies.

Sarton, George. (1964) AHistory of Science: Ancient Science Through the Golden Age of Greece (New York: Wiley Science Editions.

Sextus Empiricus. (200BC) Against the Professors.

Simplicius. (530ADa) Onthe Heavens.

Simplicius. (530ADb) Physics.

Theophrastus. (320BCa) Causesof Plants.

Theophrastus. (320BCb) Doctrinesof Natural Philosophy.

Theophrastus. (320BCc) On Sense Perception.

[1]Some skepticism isrecommended about the eclipse story, given first in Herodotus Persian Wars 1.74. See Sarton(1964, pp. 170-71).

[2]But see Lloyd (1970,pp. 18-20), who thinks Thales was speaking of the origin of different sorts ofmatter rather than their present composition.

[3]Most of theClassical references in this paper can be found in Nahm (1964), though I havetranslated his titles into English.

[4]Chronological dataon the various ancients comes from Lloyd (1970) or the Oxford ClassicalDictionary.

[5]Simplicius, 530ADb,6r: ‘... he regards [the basic substance] as not indeterminate butdeterminate.’

[6]See also thesearching criticisms in Theophrastus (320BCc, 49-82).