Bertrand Russell and F.C. Copleston Debate the Existence of God, 1948

On Jan­u­ary 28, 1948 the British philoso­phers F.C. Cople­ston and Bertrand Rus­sell squared off on BBC radio for a debate on the exis­tence of God. Cople­ston was a Jesuit priest who believed in God. Rus­sell main­tained that while he was tech­ni­cal­ly agnos­tic on the exis­tence of the Judeo-Chris­t­ian God–just as he was tech­ni­cal­ly agnos­tic on the exis­tence of the Greek gods Zeus and Poseidon–he was for all intents and pur­pos­es an athe­ist.

The famous debate is divid­ed into two parts: meta­phys­i­cal and moral. In the meta­phys­i­cal part, which is pre­sent­ed here, Cople­ston espous­es what is known as the cos­mo­log­i­cal argu­ment for the exis­tence of God. Ele­ments of the cos­mo­log­i­cal argu­ment go back at least as far as Pla­to and Aris­to­tle, who held that the uni­verse required a “prime mover” out­side of itself. The ver­sion embraced by Cople­ston is derived from one of Thomas Aquinas’ five ways to prove the exis­tence of God. In his Sum­ma The­o­log­i­ca, Aquinas writes:

The third way is tak­en from pos­si­bil­i­ty and neces­si­ty and runs thus. We find in nature things that are pos­si­ble to be and not pos­si­ble to be, since they are found to be gen­er­at­ed and cor­rupt­ed. But it is impos­si­ble for these always to exist, for that which can not-be at some time is not. There­fore, if every­thing can not-be, then at one time there was noth­ing in exis­tence, because that which does not exist begins to exist only through some­thing already exist­ing. There­fore if at one time noth­ing was in exis­tence, it would have been impos­si­ble for any­thing to have begun to exist; and thus now noth­ing would be in existence–which is absurd. There­fore, not all beings are mere­ly pos­si­ble, but there must exist some­thing the exis­tence of which is nec­es­sary. But every nec­es­sary thing has its neces­si­ty caused by anoth­er, or not. Now it is impos­si­ble to go on to infin­i­ty in nec­es­sary things which have their neces­si­ty caused by anoth­er, as has already been proved in regard to effi­cient caus­es. There­fore, we can­not but admit the exis­tence of some being hav­ing of itself its own neces­si­ty, and not receiv­ing it from anoth­er, but rather caus­ing in oth­ers their neces­si­ty. This all men speak of as God.

Cople­ston adopts Got­tfried Wil­helm Leib­niz’s Prin­ci­ple of Suf­fi­cient Rea­son as a cor­ner­stone of his argu­ment. In his 1714 essay “The Prin­ci­ples of Nature and Grace, Based on Rea­son,” Leib­niz asserts that noth­ing can exist with­out a suf­fi­cient rea­son, includ­ing the Uni­verse. “This suf­fi­cient rea­son for the exis­tence of the Uni­verse can­not be found in the series of con­tin­gent things,” writes Leib­niz. “The suf­fi­cient rea­son, there­fore, which needs not fur­ther rea­son, must be out­side of this series of con­tin­gent things and is found in a sub­stance which…is a nec­es­sary being bear­ing the rea­son for its exis­tence with­in itself; oth­er­wise we should not yet have a suf­fi­cient rea­son with which to stop. This final rea­son for things is called God.”

Rus­sell takes excep­tion to Cople­ston’s use of Leib­niz’s con­cept of a nec­es­sary being. The term “nec­es­sary,” he argues, can only be applied to ana­lyt­ic propo­si­tions–propo­si­tions which are derived log­i­cal­ly and which would be self-con­tra­dic­to­ry to deny. An ana­lyt­ic propo­si­tion would fall under Leib­niz’s cat­e­go­ry of “truths of rea­son,” or a pri­ori truths. Yet Cople­ston admits his argu­ment is based on a pos­te­ri­ori grounds, or what Leib­niz called “truths of fact.” Rus­sell first poked holes in Leib­niz’s ver­sion of the cos­mo­log­i­cal argu­ment near­ly half a cen­tu­ry before his debate with Cople­ston. In A Crit­i­cal Expo­si­tion of the Phi­los­o­phy of Leib­niz, pub­lished in 1900, Rus­sell says of the cos­mo­log­i­cal argu­ment:

It has a for­mal vice, in that it starts from finite exis­tence as its datum, and admit­ting this to be con­tin­gent, it pro­ceeds to infer an exis­tent which is not con­tin­gent. But as the pre­miss is con­tin­gent, the con­clu­sion also must be con­tin­gent. This is only to be avoid­ed by point­ing out that the argu­ment is ana­lyt­ic, that it pro­ceeds from a com­plex propo­si­tion to one which is log­i­cal­ly pre­sup­posed in it, and that nec­es­sary truths may be involved in those that are con­tin­gent. But such a pro­ce­dure is not prop­er­ly a proof of the pre­sup­po­si­tion. If a judge­ment A pre­sup­pos­es anoth­er B, then, no doubt, if A is true, B is true. But it is impos­si­ble that there should be valid grounds for admit­ting A, which are not also grounds for admit­ting B. In Euclid, for exam­ple, if you admit the propo­si­tions, you must admit the axioms; but it would be absurd to give this as a rea­son for admit­ting the axioms.

Per­haps the most mem­o­rable moment of the debate on the cos­mo­log­i­cal argu­ment comes near the end, when Rus­sell crit­i­cizes Cople­ston’s asser­tion that because every­thing con­tained with­in the Uni­verse is con­tin­gent, the Uni­verse as a whole must also be con­tin­gent. “I can illus­trate what seems to me your fal­la­cy,” says Rus­sell. “Every man who exists has a moth­er, and it seems to me your argu­ment is that there­fore the human race must have a moth­er, but obvi­ous­ly the human race has­n’t a mother–that’s a dif­fer­ent log­i­cal sphere.” For Rus­sell it was enough to accept that the Uni­verse sim­ply exists. Or as David Hume points out in his Dia­logues Con­cern­ing Nat­ur­al Reli­gion, if there must be a nec­es­sar­i­ly exis­tent being, why can’t it be the Uni­verse as a whole?

The audio ver­sion of the debate above is abridged. To read a tran­script of the entire debate, click here to open the text in a new win­dow.

Relat­ed con­tent:

Face to Face with Bertrand Rus­sell: ‘Love is Wise, Hatred is Fool­ish’

Three Pas­sions of Bertrand Rus­sell (and a Col­lec­tion of Free Texts)