Five Ways (Aquinas)

Thomas Aquinas, the 13th-century Dominican friar and theologian who formalised the "Five Ways" intended to demonstrate God's existence. In the picture, he sustains the Bible and the Roman Catholic Church in his hands.

The Quinque viæ (Latin for "Five Ways") (sometimes called "five proofs") are five logical arguments for the existence of God summarized by the 13th-century Catholic philosopher and theologian Thomas Aquinas in his book Summa Theologica. They are:

1. the argument from "first mover";
2. the argument from universal causation;
3. the argument from contingency;
4. the argument from degree;
5. the argument from final cause or ends ("teleological argument").

Aquinas expands the first of these – God as the "unmoved mover" – in his Summa contra Gentiles.

Quotes

• The existence of God may be proved in five ways. The first and most manifest way is the argument from motion. ...Whatever is in motion is moved by another, for nothing can be in motion except it have a potentiality for that toward which it is being moved. ...It is ...impossible that from the same point of view and in the same way anything should be both moved and mover, or that it should move itself. Therefore, whatever is in motion must be put in motion by another. If that by which it is put in motion be itself put in motion, then this also must needs be put in motion by another, and that by another again. This cannot go on to infinity, because then there would be no first mover; as the staff only moves because it is put into motion by the hand. Therefore it is necessary to arrive at a First Mover, put in motion by no other; and this everyone understands to be God.

The second way is from the nature of the efficient cause. In the world of sense we find there is an order of efficient causes. There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible. Now in efficient causes it is not possible to go on to infinity, because in all efficient causes following in order, the first is the cause of the intermediate cause, and the intermediate is the cause of the ultimate cause, whether the intermediate cause be several, or only one. Now to take away the cause is to take away the effect. Therefore, if there be no first cause among efficient causes, there will be no ultimate, nor any intermediate cause. But if in efficient causes it is possible to go on to infinity, there will be no first efficient cause, neither will there be an ultimate effect, nor any intermediate efficient causes; all of which is plainly false. Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God.

The third way is taken from possibility and necessity, and runs thus. We find in nature things that are possible to be and not to be, since they are found to be generated, and to corrupt, and consequently, they are possible to be and not to be. But it is impossible for these always to exist, for that which is possible not to be at some time is not. Therefore, if everything is possible not to be, then at one time there could have been nothing in existence. Now if this were true, even now there would be nothing in existence, because that which does not exist only begins to exist by 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 even 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 either 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 been already proved in regard to efficient causes. Therefore we cannot but postulate 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.

The fourth way is taken from the gradation to be found in things. Among beings there are some more and some less good, true, noble and the like. But "more" and "less" are predicated of different things, according as they resemble in their different ways something which is the maximum, as a thing is said to be hotter according as it more nearly resembles that which is hottest; so that there is something which is truest, something best, something noblest and, consequently, something which is uttermost being; for those things that are greatest in truth are greatest in being, as it is written in Metaph. ii. Now the maximum in any genus is the cause of all in that genus; as fire, which is the maximum heat, is the cause of all hot things. Therefore there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God.

The fifth way is taken from the governance of the world. We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.

• • Thomas Aquinas, Summa Theologica (1265–1274) I, Q.2, Art. 3, Obj. 2 in The "Summa Theologica" of St. Thomas Aquinas (1911) Tr. Fathers of the English Dominican Province, Vol. 1, pp. 24-25.

Quotes about

• A cosmological argument is an argument to the existence of God from the existence of some finite object or, more specifically, a complex physical universe. There have been many versions of the cosmological argument given over the past two-and-a-half millennia; the most quoted are the second and third of Aquinas’s five ways to show the existence of God. However, Aquinas’s ‘five ways’, or rather the first four of his five ways, seem to me to be one of his least successful pieces of philosophy.
  • Richard Swinburne, The Existence of God, Clarendon Press, Oxford, 2nd Edition, pp. 136-137. ISBN 0–19–927168–2

• [T]he Five Ways fail […] principally because it is much more difficult than at first appears to separate them from their background in medieval cosmology. Any contemporary cosmological argument would have to be much more different from the arguments of Aquinas than scholastic modernizations customarily are.
  • Anthony Kenny, The Five Ways: St. Thomas Aquinas' Proofs of God's Existence, New York: Routledge (2003), pp. 3-4

• Aquinas believes that human beings (even in our earthly condition here below) can have knowledge, scientific knowledge of God's existence, as well as knowledge that he has such attributes as simplicity, eternità, immateriality, immutability, and the line. In Summa Theologiae Aquinas sets out his famous Five Ways or five proofs of God's existence: in Summa Contra Gentiles he sets out the proof from motion in much greater detail; and in each case he follows these alleged demonstrations with alleged demonstrations that God possesses the attributes just mentioned. So natural knowledge of God is possible. [...] So most of those who believe in God do so on faith. Fundamentally, for Aquinas, to accept a proposition on faith is to accept it on God's authority; faith is a manner of "believing God" (ST, IIa, IIae, ii, 2) "for that which is above reason we believe only because God has revealed it" (SCG, I, 9).
  • Alving Plantinga, The Analytic Theist: An Alving Plantinga Reader, Wm. B. Eerdmans Publishing, 1998. ISBN 9780802842299. Ch. "Reason and Belief in God: Reformed Epistemology, pp. 125-126

• Of these ‘ways of being’ of the world around us, noted with greater or lesser understanding, but with equal evidence, by philosophers and common intelligence, there are two that modern science has marvellously explored, ascertained and deepened beyond all expectations:

1. the mutability of things, including their birth and their end;
2. the order of purpose that shines in every corner of the cosmos.

The contribution thus made by the sciences to the two philosophical demonstrations, which hinge on them and constitute the first and fifth ways, is most remarkable. To the first, physics in particular has contributed an inexhaustible mine of experience, revealing the fact of mutability in the deepest recesses of nature, where no human mind could ever before have suspected its existence or extent, and providing a multiplicity of empirical facts that are a very valuable aid to philosophical reasoning. We say aid because the direction of these transformations, although ascertained by modern physics, seems to us to go beyond the value of a simple confirmation and to attain almost the structure and degree of physical argument that is largely new and more acceptable, persuasive and pleasing to many minds.

With equal richness, the sciences, especially astronomy and biology, have recently provided the subject with order such a wealth of knowledge and such an intoxicating vision, so to speak, of the conceptual unity that animates the cosmos and of the purpose that directs its course, as to anticipate for modern man that joy which the Poet imagined in the empyrean heaven when he saw how in God ‘there is contained — bound with love in a volume — that which is spread throughout the universe’.

However, Providence has arranged that the notion of God, so essential to the life of every man, as can be easily deduced from a simple glance at the world, so that not to understand it is foolishness, should be confirmed by every deepening and progress of scientific knowledge.

• • Di questi «modi di essere» del mondo che ci circonda, rilevati con maggiore o minore comprensione, ma con eguale evidenza, dal filosofo e dalla comune intelligenza, due sono che le scienze moderne hanno maravigliosamente scandagliati, accertati e approfonditi oltre ogni attesa:

1. la mutabilità delle cose, compreso il loro nascere e la loro fine;
2. l’ordine di finalità che riluce in ogni angolo del cosmo.

Il contributo così prestato dalle scienze alle due dimostrazioni filosofiche, che su di esse s’imperniano e che costituiscono la prima e la quinta via, è notevolissimo. Alla prima la fisica specialmente ha conferito una inesauribile miniera di esperienze, rivelando il fatto della mutabilità in profondi recessi della natura, dove prima di ora nessuna mente umana poteva mai neanche sospettarne l’esistenza e l’ampiezza, e fornendo una moltiplicità di fatti empirici, che sono un validissimo sussidio al ragionamento filosofico. Diciamo sussidio; perché la direzione, invece, delle medesime trasformazioni, pur accertate dalla fisica moderna, Ci sembra che superi il valore di una semplice conferma e consegua quasi la struttura e il grado di argomento fisico per gran parte nuovo e a molte menti più accettevole, persuasivo e gradito.

Con pari ricchezza le scienze, specialmente astronomiche e biologiche, hanno procurato negli ultimi tempi all’argomento dell’ordine un tale corredo di cognizioni e una tale visione, per così dire, inebriante, della unità concettuale che anima il cosmo, e della finalità che ne dirige il cammino, da anticipare all’uomo moderno quel gaudio, che il Poeta immaginava nel cielo empireo, allorché vide come in Dio «s’interna — legato con amore in un volume — ciò che per l’universo si squaderna».

Tuttavia la Provvidenza ha disposto che la nozione di Dio, tanto essenziale alla vita di ciascun uomo, come può trarsi facilmente da un semplice sguardo gettato sul mondo, in guisa che il non comprenderne la voce è stoltezza, così riceva conferma da ogni approfondimento e progresso delle cognizioni scientifiche.

• • • Pope Pius XII. As quoted in Allocution to the Pontifical Academy of Sciences, Dizionario Italiano di Scienza e Fede (November 22 , 1951)

• If the primitive experience of the ancients could offer reason sufficient arguments for the demonstration of God's existence, with the broadening and deepening of the field of experience itself, the footprint of the Eternal now shines more brightly and clearly in the visible world. It therefore seems worthwhile to re-examine, on the basis of new scientific discoveries, the classic proofs of the Angelic Doctor, especially those derived from the motion and order of the universe; that is, to investigate whether and to what extent a deeper knowledge of the structure of the macrocosm and microcosm contributes to strengthening philosophical arguments; and then to consider, the other hand, whether and to what extent they have been shaken, as is often claimed, by modern physics having formulated new fundamental principles and abolished or modified ancient concepts whose meaning was perhaps considered fixed and defined in the past, such as time, space, motion, causality and substance, concepts that are extremely important for the question that now concerns us. Rather than a revision of the philosophical proofs, it is therefore a question here of scrutinising the physical bases — and we shall necessarily have to restrict ourselves to only a few, for reasons of time — from which those arguments derive. Nor are there any surprises to be feared: science itself does not intend to leave that world which, today as yesterday, presents itself with those five ‘modes of being’ from which the philosophical demonstration of the existence of God takes its starting point and its strength.
  • Se la primitiva esperienza degli antichi poté offrire alla ragione sufficienti argomenti per la dimostrazione della esistenza di Dio; con l’ampliarsi e l’approfondirsi del campo della esperienza medesima, più scintillante e più netta rifulge ora l’orma dell’Eterno nel mondo visibile. Sembra quindi proficuo riesaminare sulla base delle nuove scoperte scientifiche le classiche prove dell’Angelico, specialmente quelle desunte dal moto e dall’ordine dell’universo; ricercare, cioè, se e quanto la più profonda conoscenza della struttura del macrocosmo e del microcosmo contribuisca a rafforzare gli argomenti filosofici; considerare poi, d’altra parte, se e fino a qual punto essi siano stati scossi, come non di rado si afferma, dall’avere la fisica moderna formulato nuovi principî fondamentali, abolito o modificato concetti antichi, il cui senso in passato era forse giudicato fisso e definito, come, per esempio, il tempo, lo spazio, il moto, la causalità, la sostanza, concetti sommamente importanti per la questione che ora ci occupa. Più che di una revisione delle prove filosofiche, si tratta dunque qui di scrutare le basi fisiche — e dovremo necessariamente, per ragione del tempo, restringerCi ad alcune soltanto —, da cui quegli argomenti derivano. Né vi sono da temere sorprese: la scienza stessa non intende di uscire da quel mondo, che oggi, come ieri, si presenta con quei cinque « modi d’essere », donde prende le mosse e il nerbo la dimostrazione filosofica della esistenza di Dio.
    • Pope Pius XII. As quoted in Allocution to the Pontifical Academy of Sciences, Dizionario Italiano di Scienza e Fede (November 22 , 1951)

See also

• Ontological argument
• God
• Existence of God

External links

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