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Arguments for the Existence of God

Philosophy of Religion

Thomas Aquinas' Five Ways (Part 2): Contingency, Goodness, Design

Information: Part 2 of an article setting out the five proofs for God's existence, as presented by Thomas Aquinas in his Summa Theologica (1265-74). Click here for Thomas Aquinas' Five Ways (Part 1): Introduction, motion, causation. A version of this article was originally published on the website

The third way: The way of CONTINGENCY

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 be corrupted, and consequently, it is possible for them to be and not to be. 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. Now if this were true, even now there would be 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 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 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. (Aquinas)

Things exist, but they could easily not! There was a time before certain things existed, and there will be a time when they no longer exist. There must also have been a time when nothing existed. This means that objects have contingent existence, which means they could or  could not exist. For Aquinas, the only thing which has always existed is God (who would therefore have necessary existence). Furthermore, Aquinas saw no way to explain how anything was here, unless something was already in existence prior to it. Thus if God did not exist, nothing else would exist.

The text in bold (above) assumes that God created the world ex nihilo (out-of-nothing). This could be challenged by some cosmologists today, who want to argue that although there was no form to matter before the 'big bang', that there something before there was anything we know.

The fourth way: The way of GOODNESS

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 most being, for those things that are greatest in truth are greatest in being... Now the maximum in any genus is the cause of all in that genus, as fire, which is the maximum of heat, is the cause of all hot things, as is said in the same book. 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. (Aquinas)

We can see in the world degrees of perfection and goodness (i.e. some things are bad, some not so bad, some are better than others etc.). Now for Aquinas, we know things are 'degrees of  x' when we compare them to the best in any genus (group of things). Now as humans have the capacity for both good and bad deeds, they cannot be the source of goodness (i.e. the most Good thing). Therefore, the maximum in the genus of morality must be something non-human and not in the world (also not completely good), which leaves us with God as the most perfect being, and the 'first cause' (or source) of all goodness and perfection.

It might be argued that this is not so much an argument for the existence of God, but for the existence of some standard of morality, or for humans to be aware of it if they are to speak meaningfully about things being good or bad, or not).


The fifth way: The way of DESIGN (or teleology)

The fifth way is taken from the governance of the world. We see that things which lack knowledge, 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 they achieve their end, not fortuitously, but designedly. Now whatever lacks knowledge cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is directed by the archer. Therefore, some intelligent being exists by whom all natural things are directed to their end; and this being we call God. (Aquinas)

Aquinas' design argument here is basically suggesting that inanimate objects (E.g. Planets), could not have ordered themselves (i.e. got themselves into the orbits they have), because they lack the intelligence to do so. Yet as the planets are aligned so perfectly, this means it must have been done so by a Being with the intelligence to do so. Now although humans are intelligent, they cannot move planets, so that leaves us with God (who Aquinas believed could).

Nature suggests a realm of order, in that things seem to have an innate sense of purpose. For Aquinas, anything which has in it a sense of purpose, requires the aid of a 'guiding hand'. For instance, an arrow only hits the target, because it has been fired by an archer. Thus if nature appears ordered, it must have a 'guiding hand', who Aquinas believed was God.

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