Gottfried Wilhelm Leibniz
Leibniz, born 1646, was a major philosopher and mathematician. He argued that God must exist, which he derived from his principle of sufficient reason; the principle of sufficient reason states that everything must have a reason or cause. Thus, the question that arises is what caused the universe?
Leibniz (1714/2004) argued that there are two types of existence: contingent existence and necessary existence; things existing contingently means that they depend on something else to exist, and therefore need sufficient reason to exist; all physical things in the world, time, space, and the universe itself exists contingently. Thus, the universe cannot cause itself; the explanation must be found in something that exists necessarily; things that exist necessarily could not have been any other way; for example, it is necessarily true that two multiplied by two is four. Leibniz’s argument is that the universe exists contingently, and the sufficient reason or cause of the universe, must be God whose existence is not contingent but necessary (Leibniz, 1714/2004, p. 43). God is not contingent, meaning that a power like God does not depend on anything else, existing outside of contingent things like space and time (Leibniz, 1714/2004, p. 43). This renders the question “what caused God?” meaningless as the question presupposes contingency.
Also, see Leibniz's principle of perfection.
Critique & Discussion
Inspired by Darwin, Dawkins argues against design in favor of evolution and the mechanisms of natural selection. However, this could be challenged as one could suggest that evolution itself is designed. Furthermore, biological evolution does not address the argument of design in biological life emerging at all, or the fine-tuning of the existing natural laws in the universe. Dawkins and similar materialistic thinkers might be good technical scientists, but they are evidently poor philosophers as they do not give enough thought to the matter. Aquinas would argue that they do not have the right character.
David Hume argued that the effects we see in the world do not necessarily have a cause, especially if the effect has only occurred once, for example the universe coming into being. Paley had anticipated some of the criticism in his original work; Paley would have argued that this does not explain away the design that is there, regardless of it occurring only once. Notice that the multiverse theory does not explain away design.
Derek Parfit, an atheist philosopher, argued that there is no explanation needed for why the universe exists; it is a brute fact that it does, and further assumptions do not clarify the matter; however, Parfit himself admits that the brute fact view is not satisfactory. The universe could be eternal; thus, no sufficient reason would be necessary to explain its existence - it has always existed. To prove this assumption, one would have to prove Leibniz wrong, which in my opinion is near impossible. (Immanuel Kant ultimately argued for God's existence, but for very different reasons).
Leibniz assumes that the principle of sufficient reason is true; however, could this principle be false? If the principle of sufficient reason is false, the consequence is that anything can happen at any time, without any cause; this does not seem intuitively true, but the possibility of the principle being false might exist. However, the criticism itself does not make sense if Leibniz's principle is false. Aristotle argued that before any scientific investigation can be done, one must establish some basic principles one must assume to be true. Aristotle called these “first principles”; an example of a first principle is the principle of non-contradiction: something cannot possess an ability or attribute, and not possess it at the same time; any scientific investigation must presuppose this principle to be true. The method of discovering the “first principles” is through Aristotelian induction; Aristotle believed that the human mind could draw true general conclusions from few, but systematic observations. Therefore, the assumption that humans can use induction to gain certainty about the world is a fundamental starting point. If the principle of non-contradiction is not assumed, then any thought or statement becomes meaningless; the entire scientific endeavor becomes useless.
Leibniz, G. F. (2004). Monadology. In Crane, T., & Farkas K. (Eds.), Metaphysics: A Guide and Anthology (p. 43-44). Oxford University Press. (Original work published in 1714).
Paley, W. (2004). Natural Theology. In Crane, T., & Farkas K. (Eds.), Metaphysics: A Guide and Anthology (p. 34-40). Oxford University Press. (Original work published in 1802).