LECTURE 3: HISTORICAL THOUGHT ON EXTRATERRESTRIAL LIFE
In Greek times, the debate was largely philosophical and did not conform to present notions of cosmology. Cosmic pluralism was a corollary to notions of infinity and the purported multitude of life-bearing worlds were more akin to parallel universes (either contemporaneously in space or infinitely recurring in time) than to different solar systems. After Thales and his student Anaximander opened the door to an infinite universe, a strong pluralist stance was adopted by the atomists, notably Leucippus, Democritus, and Epicurus. While these were prominent thinkers, their opponents—Plato and Aristotle—had greater effect. They argued that the Earth is unique and that there can be no other systems of worlds.[1] This stance neatly dovetailed with later Christian ideas[2] and pluralism was effectively suppressed for a millennium.[citation needed]
Scholastic thinkers
Eventually the Ptolemaic-Aristotelian system was challenged and pluralism reasserted, first tentatively by scholastics and then more seriously by followers of Copernicus. The telescope appeared to prove that a multitude of life was reasonable and an expression of God's creative omnipotence; still powerful theological opponents, meanwhile, continued to insist that although the Earth may have been displaced from the center of the cosmos, it was still the unique focus of God's creation. Thinkers such as Johannes Kepler were willing to admit the possibility of pluralism without truly supporting it.
Enlightenment
During the Scientific Revolution and the later Enlightenment, cosmic pluralism became a mainstream possibility. Bernard le Bovier de Fontenelle's Entretiens sur la pluralité des mondes (Conversations on the Plurality of Worlds) of 1686 was an important work from this period, speculating on pluralism and describing the new Copernican cosmology.[1] Pluralism was also championed by philosophers such as John Locke, astronomers such as William Herschel and even politicians, including John Adams and Benjamin Franklin. As greater scientific skepticism and rigour were applied to the question it ceased to be simply a matter of philosophy and theology and was properly bounded by astronomy and biology.
Modern thought
In the late nineteenth and twentieth centuries the term "cosmic pluralism" became largely archaic as knowledge diversified and the speculation on extraterrestrial life focussed on particular bodies and observations. The historic debate continues to have a modern parallels, however. Carl Sagan and Frank Drake, for instance, could well be considered "pluralists" while proponents of the Rare Earth hypothesis are modern skeptics.
Belief in extraterrestrial life may have been present in ancient India, Egypt, Arabia, China, Babylon, Assyria and Sumer, although in these societies, cosmology was fundamentally supernatural and the notion of alien life is difficult to distinguish from that of gods, demons, and such. The first important Western thinkers to argue systematically for a universe full of other planets and, therefore, possible extraterrestrial life were the ancient Greek writer Thales and his student Anaximander in the 7th and 6th centuries B.C. The atomists of Greece took up the idea, arguing that an infinite universe ought to have an infinity of populated worlds. Ancient Greek cosmology worked against the idea of extraterrestrial life in one critical respect, however: the geocentric universe. Championed by Aristotle and codified by Ptolemy, it favored the Earth and Earth-life (Aristotle denied there could be a plurality of worlds) and seemingly rendered extraterrestrial life philosophically untenable. Lucian in his novels described inhabitants of the Moon and other celestial bodies as humanoids, but with significant differences from humans.
Authors of Jewish sources also considered extraterrestrial life. The Talmud states that there are at least 18,000 other worlds, but provides little elaboration on the nature of the worlds and on whether they are physical or spiritual. Based on this, however, the 18th century exposition "Sefer HaB'rit" posits that extraterrestrial creatures exist but that they have no free will (and are thus equivalent to animal life). It adds that human beings should not expect creatures from another world to resemble earthly life, any more than sea creatures resemble land animals.[7][8]
Hindu beliefs of endlessly repeated cycles of life have led to descriptions of multiple worlds in existence and their mutual contacts means 'contact' as in Mahasamparka = the great contact). According to Hindu scriptures there are innumerable universes created by the Supreme Personality of Godhead to facilitate the fulfillment of the separated desires of innumerable living entities. However, the purpose of such creations is to bring back the deluded souls to correct understanding about the purpose of life. Apart from the innumerable universes which are material, there is also the existence of unlimited spiritual world, where the purified living entities live with perfect conception about life and ultimate reality. The life of these purified beings is centered around loving devotional services to Supreme Personality of Godhead. The spiritually aspiring saints and devotees as well as thoughtful men of material world have been getting guidance and help from these purified living entities of spiritual world from time immemorial. However, the relevance of such descriptions has to be evaluated in the context of a correct understanding of geography and science at those times.
Within Islam, the statement of the Qur'an "All praise belongs to God, Lord of all the worlds" indicates multiple universal bodies and maybe even multiple universes that may indicate extraterrestrial and even extradimensional life. Surat Al-Jinn also mentioned a statement from a Jinn regarding the current status and ability of his group in the heavens. A more direct reference from Quran is presented by Mirza Tahir Ahmad as a proof that life on other planets may exist according to Quran. In his book, Revelation, Rationality, Knowledge & Truth, he quotes verse 42:29 "And among His Signs is the creation of the heavens and the earth, and of whatever living creatures (da'bbah) He has spread forth in both..."; according to this verse there is life in heavens. According to the same verse "And He has the power to gather them together (jam-'i-him) when He will so please"; indicates the bringing together the life on Earth and the life elsewhere in the universe. The verse does not specify the time or the place of this meeting but rather states that this event will most certainly come to pass whenever God so desires. It should be pointed out that the Arabic term Jam-i-him used to express the gathering event can imply either a physical encounter or a contact through communication.[9]
When Christianity spread throughout the West, the Ptolemaic system became very widely accepted, and although the Church never issued any formal pronouncement on the question of alien life[10] at least tacitly the idea was aberrant. In 1277 the Bishop of Paris, Étienne Tempier, did overturn Aristotle on one point: God could have created more than one world (given His omnipotence) yet we know by revelation He only made one. Taking a further step and arguing that aliens actually existed remained rare. Notably, Cardinal Nicholas of Cusa speculated about aliens on the moon and sun.
There was a dramatic shift in thinking initiated by the invention of the telescope and the Copernican assault on geocentric cosmology. Once it became clear that the Earth was merely one planet amongst countless bodies in the universe the extraterrestrial idea moved towards the scientific mainstream. God's omnipotence, it could be argued, not only allowed for other worlds and other life, on some level it necessitated them. The best known early-modern proponent of such ideas was Giordano Bruno, who argued in the 16th century for an infinite universe in which every star is surrounded by its own solar system; he was eventually burned at the stake by the Catholic church for his heretical ideas. The Catholic church under John Paul II apologized for this. In the early 17th century the Czech astronomer Anton Maria Schyrleus of Rheita mused that "if Jupiter has…inhabitants…they must be larger and more beautiful than the inhabitants of the Earth, in proportion to the [characteristics] of the two spheres."[11] Dominican monk Tommaso Campanella wrote about a Solarian alien race in his Civitas Solis.
Such comparisons also appeared in poetry of the era. In "The Creation: a Philosophical Poem in Seven Books" (1712) Sir Richard Blackmore observed: "We may pronounce each orb sustains a race / Of living things adapted to the place". The didactic poet Henry More took up the classical theme of the Greek Democritus in "Democritus Platonissans, or an Essay Upon the Infinity of Worlds" (1647). With the new relative viewpoint that the Copernican revolution had wrought, he suggested "our world's sunne / Becomes a starre elsewhere." Fontanelle's "Conversations on the Plurality of Worlds" (translated into English in 1686) offered similar excursions on the possibility of extraterrestrial life, expanding rather than denying the creative sphere of a Maker.
The possibility of extraterrestrials remained a widespread speculation as scientific discovery accelerated. William Herschel, the discoverer of Uranus, was one of many 18th-19th century astronomers convinced that our Solar System, and perhaps others, would be well populated by alien life. Other luminaries of the period who championed "cosmic pluralism" included Immanuel Kant and Benjamin Franklin. At the height of the Enlightenment even the Sun and Moon were considered candidates for extraterrestrial inhabitants.
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