In my 2008 book “The Clarity of God’s Existence” I wrote about the principle of clarity. In that work the principle of clarity states that if the failure to know God (unbelief) is without excuse, then it must be clear that God exists. I set the context for this by considering the failed attempts of the Enlightenment and the failed attempts of the post-Enlightenment. The skepticism of Hume and Kant and a low view of reason seem to have won the day.
Preface, “The Clarity of God’s Existence”
Philosophically, the Enlightenment began when Descartes made a search for clear and distinct ideas to serve as a foundation for knowledge. Currently, both secular and religious thinkers agree that the Enlightenment program failed. For instance, Alvin Plantinga denies that attempts to find such a foundation can succeed, and Kelly James Clark asserts that the Enlightenment had an overly stringent conception of rationality that should be abandoned for intuitive and common sense religious belief. Similarly, Graham Oppy argues that while there are no successful proofs for a divine being, there are also no successful proofs against the existence of a divine being. The only irrational position, according to Oppy, is to maintain that reason can prove anything about God’s existence one way or the other. Even a recent edited volume which claims to be a defense of natural theology against the skepticism of David Hume concedes that there is no argument from natural theology that proves the existence of God such that it is irrational to maintain the opposite conclusion. The book goes so far as to maintain that it is unlikely that any metaphysical claim can be proven in this manner. The skepticism of Hume seems to have prevailed even in a book claiming to defend against Hume.
So what happened to the search for clear and distinct ideas on which to build a foundation for knowledge? It seems to have been abandoned in a two-fold process: first, inadequate candidates for clear and distinct ideas were used as foundations, and second these were shown to be insufficient by philosophers such as Hume and Kant. The important challenge from Hume and Kant is not their particular arguments against specific religious beliefs, such as miracles or scripture or the resurrection of the dead, but their critique of reason. It is the denial of the human ability to use reason to know about reality that is devastating and pervasive. As noted above, even those who defend religious beliefs against Hume have swallowed this pill of skepticism. The acceptance of the critique of reason is not incidental—the challenge from Hume and Kant is incisive and devastating to previous attempts to attain certainty about reality.
If nothing is clear, what are the implications? Specifically, if nothing is clear about basic features of reality, such as what has existed from eternity, can humans be held responsible or accountable for believing anything? There is a relationship between responsibility and clarity such that if a person is responsible to believe something, it must be clear, and if it is not clear then there can be no responsibility for belief. Or, if one wishes to admit of degrees of responsibility and clarity, then it can be affirmed that there is a relationship between the degree to which something is clear and the degree to which a person is responsible for belief. This means that the highest level of responsibility, such as everlasting punishment in hell, requires the highest level of clarity.
For something to be clear in this sense is for it to be based on clear distinctions, such as between a and non-a, or being and non-being. The denial of clarity involves the denial that there are clear distinctions—the opposite of what is clear is impossible because it denies the very distinction necessary for intelligibility. In such a case there would be no excuse for believing the opposite; one would be responsible for believing what is clear. Realizing that not everything is clear in this way, Enlightenment thinkers sought for a foundation of clarity. If the foundation is not clear then nothing else will be clear; alternative structures for belief such as coherentism still require that there are clear principles to guide belief (such as the law of non-contradiction). For Christianity the most basic belief on which the rest of the Christian worldview is founded is the existence of God. Furthermore, Christianity maintains that the failure to believe in God is inexcusable (the highest level of responsibility).
The following is not a proof for the existence of God. It is one step removed from that. The following is an examination of why it is important for Christianity to demonstrate the clarity of God’s existence. This will include needing to wade through numerous attempts by Christians to avoid the need for clarity, and insufficient alternatives to clarity such as plausibility, probability, warrant, or intuition and common sense. It will also require focusing as sharply as possible on the challenge to reason from Hume and Kant, and how previous theistic arguments have failed. While the topic of God’s existence always gets significant attention in philosophical literature, the need for clarity to establish inexcusability is conspicuously absent.