- Blue – Main argument
- Red – Argument Against
- Orange- Critical analysis
- Purple – Scholars
Philosophical argumentation aims to use reason as the basis of debate in an attempt to avoid fallacies such as an appeal to emotion or common opinion. When presenting a logical argument, there are two methods of obtaining knowledge used to give evidence towards the conclusion; a priori and a posteriori. A priori knowledge is gained prior to experience and is considered by most to be purely analytic, meaning it is true by definition. This method of inquiry cannot err from human sense limitations and, consequentially, is seen by some as the only way to form absolute truths. A posteriori knowledge follows after experience. David Hume called information proved undoubtedly by empiricism “matters of fact.” Hume’s distinction does not mean they cannot be proved false, rather, they can only be proved false by clear evidence to the contrary. Modern science has its foundation in a posteriori knowledge.
In the debate I will be proposing that, when arguing for the existence of God, a posteriori arguments are more convincing than a priori. To make this case I will be referencing William Paley, Richard Swinburne, Immanuel Kant, David Hume and St. Anselm of Canterbury.
Firstly, one of the prominent arguments for God’s existence uses a posteriori evidence to make its case- The Teleological argument. In Natural Theology, William Paley proposes, through use of analogy, that the world is too complex to have happened by chance. The human eye, according to Paley, is evidence that God has designed human-beings because it has great complexity. The most compelling argument he raises comes in the form of an analogy by which he draws a comparison between a watch and the world. He invites readers to consider how a watch comes into being. The watch could not have occurred by accident because of the order and purpose it possesses. Therefore, no-one could reasonably suggest that a watch could form without a designer. Following further a posteriori evidence we can conclude that there appears to be great complexity to the world and the universe as a whole, leaving us with a logical conclusion that a designer is required. Richard Swinburne also examines the probability of life developing, likening the odds to drawing 10 consecutive Aces of Hearts from a card machine shuffling 10 packs of cards. Swinburne uses a posteriori evidence by observing the constants (such as gravity) in our universe which have allowed life to develop. He concludes that the likelihood of the universe being this way is comparable to drawing the 10 Aces of Hearts. It demands an explanation and that explanation is a designer God.
Alternatively, Paley’s arguments can be faulted with the emergence of evolution as the theory of how life developed. Scientific evidence can now point to how the human eye has developed over millions of years, rather than being the result of a design.
The Teleological argument’s a posteriori approach faces problems which Saint Anselm’s Ontological argument could be seen to overcome. The Ontological argument aims to prove God’s existence a priori. He achieves this through a deductive argument focused on the definition of God. In his first premise, Anselm declares “God is a being than which none greater can be imagined.” If the premise is accepted, logic dictates that God must exist by definition. It is argued that if we are able to conceive of a perfect being, that being would be imperfect if it only existed in the mind. According to St. Anselm, existence is better than non-existence and therefore a perfect being would necessarily have to exist in reality. Due to its deductive nature, the Ontological argument should have a case for God’s existence because the conclusion must be correct if the premises cannot be proved wrong. This type of argument is, therefore, more effective because no evidence could be used to counter it.
However, many argue that the Ontological argument does nothing to prove the existence of God. Immanuel Kant explained that existence cannot be considered a predicate. We can say that if God existed He would have these particular qualities, but it cannot be said that existence is anything other than a relation to the world. Therefore, claiming a perfect being must exist rather than not exist is an empty statement. Existence is not a property of the subject; it must be observed to be verified.
Finally, the Cosmological arguments attempt to use a posteriori knowledge to prove God’s existence. Thomas Aquinas proposes the premise; all things that exist need a cause for their existence. He then proceeds to claim that it is logically impossible for an infinite regress of causes, meaning there must be a first cause which is uncaused. This line of argument was also presented in the Kalam argument which states that all things that begin to exist must have a cause. Furthermore, all things that exist derive from either a natural or personal cause. The argument concludes that since no laws of nature existed before the universe, the origins cannot be found in a natural cause. Therefore, the only possibility is a personal being. Eventually, following further premises, the argument presents us with a personal being, outside of time and space, which by definition does not require a cause and has extreme power.
Similarly to the Teleological argument, the Cosmological is not without its flaws. David Hume condemns the Cosmological arguments because of their logical fallacies. One such fallacy is the “fallacy of composition”, which outlines why it is not possible to gain truth about the whole solely through comparisons to its parts. With regards to the argument, observing that things appear to need a cause cannot guarantee the universe must require one itself. We are unable to observe how the universe began, therefore, we will always be making inductive leaps with these types of conclusions. Furthermore, there is no possible comparison we can make with other universes, meaning we are left with pure speculation.
Nevertheless, the Cosmological argument’s use of a posteriori proof holds up better to scrutiny than the Ontological argument. While it has its flaws, it still leaves a logical possibility that a creator God does exist.
To conclude, a posterori proof offers more persuasive evidence for the existence of God than a priori. Kant successfully shows how God’s existence is not found analytically, meaning, if there is any proof of God, it might be best found empirically. Although this was, of course, rejected by Kant also.
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