Cosmological argument

=== Argument from contingency ===

In the [[scholasticism|scholastic]] era, [[Aquinas]] formulated the "argument from [[Contingency (philosophy)|contingency]]", following [[Aristotle]] in claiming that [[Unmoved mover|there must be something to explain why the Universe exists]]. Since the Universe could, under different circumstances, conceivably ''not'' exist (contingency), its existence must have a cause – not merely another contingent thing, but something that exists by [[INUS|necessity]] (something that ''must'' exist in order for anything else to exist).<ref>''Summa Theologiae, I:'' 2, 3</ref> In other words, even if the Universe has always existed, it still owes its existence to an [[Primum movens|uncaused cause]],<ref>Aquinas was an ardent student of Aristotle's works, a significant number of which had only recently been translated into Latin by [[William of Moerbeke]] .</ref> Aquinas further said: "...&nbsp;and this we understand to be God."<ref>''Summa Theologiae, I: '' 2,3</ref>

Aquinas's argument from contingency allows for the possibility of a Universe that has no beginning in time. It is a form of argument from universal [[Causality|causation]]. Aquinas observed that, in nature, there were things with contingent existences. Since it is possible for such things not to exist, there must be some time at which these things did not in fact exist. Thus, according to Aquinas, there must have been a time when nothing existed. If this is so, there would exist nothing that could bring anything into existence. Contingent beings, therefore, are insufficient to account for the existence of contingent beings: there must exist a ''[[INUS|necessary]]'' being whose non-existence is an impossibility, and from which the existence of all contingent beings is ultimately derived.

Aquinas' argument from contingency may also be formulated like this: if each contingently existing being considers himself Bn, then, because he exists contingently, he depends for his existence on a prior being Bn-1. Now, Bn-1 likewise, if it is contingent, depends on Bn-2. Nevertheless, this series cannot go on until Infinity. At a certain time, we will arrive at a B1, the First Being in existence, and since there is no "zeroth" Being or B0, B1 exists Necessarily, i.e. is not a contingent being. This was Aquinas' Third Way, under Question 2, Article 3 in the Summa Theologica<ref>{{cite web | url=https://www.newadvent.org/summa/1002.htm#article3 | title=SUMMA THEOLOGIAE: The existence of God (Prima Pars, Q. 2) }}</ref>

The German philosopher [[Gottfried Leibniz]] made a similar argument with his [[principle of sufficient reason]] in 1714. "There can be found no fact that is true or existent, or any true proposition," he wrote, "without there being a sufficient reason for its being so and not otherwise, although we cannot know these reasons in most cases." He formulated the cosmological argument succinctly: "Why is there something rather than nothing?  The sufficient reason ... is found in a substance which ... is a necessary being bearing the reason for its existence within itself."<ref>''Monadologie'' (1714). [[Nicholas Rescher]], trans., 1991. ''The Monadology: An Edition for Students''. Uni. of Pittsburgh Press. [http://www.earlymoderntexts.com/pdf/leibmon.pdf Jonathan Bennett's translation.] [http://www.rbjones.com/rbjpub/philos/classics/leibniz/monad.htm Latta's translation.] {{Webarchive|url=https://web.archive.org/web/20151117200947/http://www.rbjones.com/rbjpub/philos/classics/leibniz/monad.htm |date=2015-11-17 }}</ref>

Leibniz's argument from contingency is one of the most popular cosmological arguments in philosophy of religion. It attempts to prove the existence of a necessary being and infer that this being is God. [[Alexander Pruss]] formulates the argument as follows:

# Every contingent fact has an explanation.
# There is a contingent fact that includes all other contingent facts.
# Therefore, there is an explanation of this fact.
# This explanation must involve a necessary being.
# This necessary being is God.<ref>Quoted from The Blackwell Companion to Natural Theology, The Leibnizian Cosmological Argument, by Alexander R. Pruss, pp.25-6</ref>

Premise 1 is a form of the [[principle of sufficient reason]] stating that all contingently true sentences (i.e. contingent facts) have a sufficient explanation as to why they are the case. Premise 2 refers to what is known as the Big Conjunctive Contingent Fact (abbreviated BCCF), and the BCCF is generally taken to be the [[logical conjunction]] of all contingent facts.<ref>Oppy, Graham. [https://www.jstor.org/stable/20008300?seq=1#page_scan_tab_contents "On 'a new cosmological argument'"]. ''Religious Studies''.</ref> It can be thought about as the sum total of all contingent reality. Premise 3 then concludes that the BCCF has an explanation, as every contingency does (in virtue of the PSR). It follows that this explanation is non-contingent (i.e. necessary); no contingency can explain the BCCF, because every contingent fact is a ''part'' of the BCCF. Statement 5, which is either seen as a premise or a conclusion, infers that the necessary being which explains the totality of contingent facts is God. Several philosophers of religion, such as Joshua Rasmussen and T. Ryan Byerly, have argued for the inference from (4) to (5).<ref>Rasmussen, Joshua. [https://www.jstor.org/stable/40270260?seq=1 "From a Necessary Being to God"]. ''International Journal for Philosophy of Religion''.</ref><ref>Byerly, Ryan T [https://academic.oup.com/analysis/article-abstract/79/1/10/5032496 "From a necessary being to a perfect being"] ''Analysis'', Volume 79, Issue 1, January 2019, pages 10-17</ref>