Action at a Distance
Action at a distance, although accepted in occult and magical traditions, has generally been excluded from physics and theology (where it has generally been assumed that even God cannot act at a distance). This article gives a brief account of the acceptance of action at a distance in magical worldviews and in voluntarist theology through the Middle Ages and into the early modern period, where it was most notably promoted in natural philosophy by Francis Bacon and Isaac Newton and in theology by René Descartes and his followers. It ends with a brief consideration of the Newtonian legacy of action at a distance as a major assumption in mainstream physics throughout the Enlightenment and into the modern period.
KeywordsGravitational Attraction Planetary Movement Early Modern Period Renaissance Period Metaphysical Dispute
Heritage and Rupture with the Tradition
The belief that things could act on other things even across a distance, with no material connection between them, was common in the magical tradition. One of the major authorities on action at a distance as far as learned magicians were concerned was the De theoria artium magicarum (On the theory of the magical arts) attributed to the Arab philosopher Al-Kindi (801–73) but perhaps written later by an unknown Latin scholar (Adamson 2007). This work, also known under the title, De radiis stellarum (On the rays of the stars), explained actions at a distance in terms of “rays”: “…each thing in this world, whether substance or accident, produces rays in its own way like the stars… Hence each place in this world contains the rays of all the things which actually exist in it” (Adamson and Pormann 2012, p. 226). The rays are held to be immaterial, and therefore the bodies emitting the rays are acting not by physical contact but at a distance. The author’s starting point was clearly a belief in stellar influence, but other prominent examples of action at a distance were magnetism and later gravity – both of which exhibited forces of attraction (and in the case of magnetism, repulsion) which could not be affected by a change of surrounding material conditions or cut off by any material barrier (although magnetism could be shielded by iron).
For those who refused to accept action at a distance, there were generally two ways to try to avoid it. The action in question was either assumed to be performed by streams (sometimes referred to as “steams”) of material effluvia (or invisibly small particles) emitted by the active body; or by a successive transmission of the action through a surrounding material medium or aether (Hesse 1963). Both were means of reducing action at a distance to indirect contact action. Often these explanations were as implausible as the magical accounts (especially when dealing with effects which could not be shielded by material barriers or effects at very great distances), but resistance to magic was always very high in the Christian tradition as a result of religious opposition (on the grounds that magical effects were always brought about by demons or even the Devil himself). But, for the historian, this means that it is often difficult to be sure whether a particular thinker believes in action at a distance or not. A number of thinkers who seem to be assuming action at a distance never explicitly say that they are making that assumption, and so there is always some doubt as to whether they might not be thinking in terms of effluvia or transmission through a surrounding medium. In what follows, we shall concentrate only on those thinkers who explicitly mention action at a distance.
Although Aristotle (384–322 BC) never explicitly discussed action at a distance, his plenist natural philosophy seemed to take it for granted that action could only take place by contact (e.g., Physics, VII, 2, 243a 32–35, and VIII, 5, 267b 6–8; De generatione et corruptione, I, 6, 322b 28–29, and 323a 33–34). Albertus Magnus (c. 1200–1280) fully examined, and rejected, the possibility of action at a distance (Kovach 1979), and his influential follower, Thomas Aquinas (1225–1274), made it axiomatic for subsequent generations of scholastic philosophers that “a thing cannot act where it is not” (e.g., Summa Theologica, Part III, Q. 64, Art. 1, Obj. 3). During the Renaissance, however, the revival of natural magic (stimulated by the rediscovery of the Corpus Hermeticum) meant that action at a distance began to appear in the thought of philosophers who believed occult traditions offered the most promising alternative to a scholasticism that was increasingly being seen as misconceived and moribund. Action at a distance can be seen to feature, for example, in Heinrich Cornelius Agrippa’s (1486–1535) De occulta philosophia (1533), Girolamo Fracastoro’s (c. 1478–1553) De sympatia et antipathia rerum (1546), in the De abditis rerum causis (1548) of Jean Fernel (1497–1558), Giambattista della Porta’s (c. 1535–1615) Magia naturalis (1558, expanded in 1589), and the Del senso delle cose e della magia naturale (1620) of Tommaso Campanella (1568–1639).
Paracelsian claims about the so-called weapon salve also stimulated debate (Debus 2002). The weapon salve was an ointment that was held by its Paracelsian advocates to magically cure wounds when it was applied to the weapon which had caused the wound, rather than to the wound itself (which was simply kept clean and dry). Anecdotal reports abounded of the effect working even when the weapon and the wounded person were separated by thousands of miles. Presumably many of these anecdotes were simply untrue, but some may well have been perfectly true; and it is not hard, with hindsight, to see why. The standard medical belief throughout the Renaissance period was that a wound could only heal after it had suppurated. Presumably, this is derived from experience; at this time (when antisepsis or asepsis was unheard of), wounds always suppurated before, eventually, healing. Medical intervention, therefore, deliberately provoked what was referred to as “laudable pus” in wounds (to accelerate the healing process) by packing them with caustic or irritant substances. It is easy for us now to see how this could result in detrimental and even fatal results. Treatment using the weapon salve, or the powder of sympathy as it was also called, meant that the wound would simply be kept clean and dry, while the ointment or powder was applied to the weapon or to a bandage soaked in blood from the wound (but then removed away from the wound) if the weapon was not available. Under these circumstances – with the wound left unperturbed by dangerous medical intervention – the wounded person had the best chance of recovery. Consequently, many of the accounts of the success of the weapon salve were based on what seemed like good empirical evidence for its efficacy. For many, therefore, the weapon salve was clearly magical and worked by action at a distance. For others, however, including one of its most famous promoters, Sir Kenelm Digby (1603–1665), it worked by contact action through an elaborate process carried out by material effluvia, even when weapon and wound were separated by continents (Hedrick 2008).
The possibility or otherwise of action at a distance also figured in metaphysical disputes as to whether God could only act where he was present. Debate on this issue was affected by the fact that God was held to be essentially omnipresent. In medieval discussions which carried over into the Renaissance period, there was a wide range of differing views. For some philosophers, his omnipresence was simply taken as proof that action at a distance was impossible. For others, however, it was supposed that God’s presence, although undeniable, was not required by the fact that he acted on all things (he could will something to happen and it would happen, but his proximity was irrelevant). Similarly, while some argued that God could not act at a distance simply because he was omnipresent, others argued that he could act at a distance, because of his omnipotence, even if, per impossibile, he were not present (Kovach 1979).
The main medieval dissenters from the view that God had to be present to act were John Duns Scotus (c. 1266–1308) and William of Ockham (c. 1287–1347). For both thinkers, it was God’s omnipotence that led them to believe in action at a distance. For Scotus the power of God and angels was so immeasurable that they did not have to be present to bring things about (Kovach 1979; Reid 2012). Similarly, for Ockham, God’s will constituted his action – for God, to will something was to bring it about – God’s presence was not relevant to the issue (Kovach 1979). Both thinkers also accepted that action at a distance in physics was also possible. Again, God’s omnipotence meant that he could endow bodies with the power of acting at a distance (Kovach 1979; Goddu 1984).
Innovative and Original Aspects
there is scarcely anything which is not more or less radiant. This is very plainly seen in the power of vision, and not less so in all kinds of magnetic virtue, and in every effect which takes place at a distance. For whatever produces an effect at a distance may be truly said to emit rays. (The Wisdom of the Ancients, “Pan, or Nature”, Bacon 2013, p. 710)
Again, if there be any magnetic power which operates by consent between the Earth and heavy bodies, between the globe of the Moon and the seas (which seems very likely in the half-monthly tidal cycle), or between the stellar heavens and the planets by which the latter are summoned and drawn to their apogees, then all these operate at very long distances indeed. (Novum organum, Book II, Aphorism 45)
Bacon’s suggestion that terrestrial gravity, the relationship between the Moon and the tides, and planetary movements might be explained by an attractive force similar to magnetism and capable of acting at a distance led a number of fellows of the newly formed Royal Society to develop an explanation for planetary movements along the same lines (Wang 2016). This culminated in the precursor to Isaac Newton’s universal principle of gravitation, developed by Robert Hooke (1635–1703) in his Attempt to Prove the Motion of the Earth (1674). Hooke wrote to Newton (1642–1727) in 1679 to ask his opinion of this theory, and from then on, Newton too embraced a belief in action at a distance and incorporated it into his theory of gravity in his Principia Mathematica of 1687. Hooke and other early fellows of the Royal Society who worked in this area did not explicitly mention actions at a distance, but nor did they try to explain the attractive forces they described in terms of effluvia or the actions of an intervening medium. Newton was similarly silent about actions at a distance in the Principia, although continental critics did not fail to notice that Newton’s gravitational attraction operated at a distance.
By the time Newton came to publish his second great book, the Opticks, in 1704, he had sufficient authority and self-confidence to write explicitly of actions at a distance. The influential Queries that he added to the end of the Opticks suggested that all physical phenomena could be explained in terms of attractive and repulsive forces operating at a distance between the particles which constituted all bodies. Even the group of eight extra queries that he added to the 1718 edition, and which suggested explanations for phenomena in terms of an intervening all-pervasive medium (which he called the aether), depended on action at a distance. The aether was held to be so subtle and tenuous that its particles were supposed to be separated from one another (comparing the tenuity of the aether with the densest substance, gold, in which the particles were assumed to be touching one another; Newton concluded that the particles of aether must be comparatively far apart). But if the particles of the aether were separated from one another, then they must be kept apart, Newton insisted, by mutually repelling forces operating across the distance between them (Henry 2011).
The metaphysical arguments as to whether God could act a distance also reappeared in the seventeenth century as a result of René Descartes’s (1596–1650) claim that God did not occupy space, since the divinity is a res cogitans, not a res extensa. In response to critics, most notably the Cambridge Platonist Henry More (1614–1687), Descartes tried to insist that God was omnipresent only according to his power, not his substance. This was effectively the same position adopted earlier by John Duns Scotus, William of Ockham, and other medieval theologians. Later Cartesians, however, such as Antoine Le Grand (1629–1699) and Nicolas Malebranche (1638–1715) tended to concede that God must also be substantially present (Reid 2008). Although this might look like a concession to the view that even an omnipotent God could not act at a distance, and therefore a betrayal of the strict substance dualism of Descartes, the real issue for the later Cartesians was that denial of the substantial presence of God might be seized upon by contemporary atheists as a means to deny the existence of God. Accordingly, the later Cartesians did not really abandon Cartesian dualism, but they played it down in their discussions of God, to avoid giving ammunition to contemporary atheists.
It seems clear that the dominant view among theologians, from the Middle Ages through the early modern period, was that God could not act at a distance, notwithstanding his omnipotence (although there were prominent dissenters from this view, such as John Duns Scotus, William of Ockham, and Descartes). It seems likely that this theological position reflected the aversion to action at a distance as an unacceptably magical notion which can be seen among Christian philosophers throughout the ages. After all, it was theologians who were mostly responsible for the aversion to magic (by insisting that all magical operations and effects were really brought about by hidden demonic activity), so it would be odd if they readily accepted a magical notion like action at a distance even when considering the actions of their omnipotent God. It was always possible, of course, to deny God’s ability to do something without compromising His supposed omnipotence, by insisting that the issue in question was logically impossible. For those who defended the idea that God could not act at a distance, action at a distance was simply deemed to be a contradiction in terms.
Impact and Legacy
Generally speaking, opposition to the concept of actio in distans was always vigorous and unyielding. It is all the more remarkable, therefore, that Newton managed to introduce action at a distance into mainstream physics for well over a century after his death (Schofield 1970; Henry 2011). The success of Newton’s Principia ensured that his more speculative claims, in the Queries added to the Opticks, about attractive and repulsive forces operating at a distance between all atoms, were taken up by succeeding generations of thinkers – mostly natural philosophers, of course, but also including Immanuel Kant (1724–1804) and John Stuart Mill (1806–1873). Reaction against Newtonian action at a distance began to appear in the first half of the nineteenth century and culminated with Albert Einstein’s (1879–1955) suggestion at the beginning of the twentieth century that there was no such thing as gravitational attraction and that gravitational phenomena that had previously been attributed to attraction at a distance were really the result of the bending of space by gravitational masses. Remarkably, however, what Einstein referred to as “spooky action at a distance” almost immediately reappeared in quantum mechanics, as a way of understanding phenomena attributed to the so-called quantum entanglement (Musser 2015). It seems that concepts of action at a distance have a way of reasserting themselves, in spite of obdurate and long-standing opposition.
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