Deism is concerned not merely with what is believed, but with the conditions under which belief may properly be called knowledge. Every philosophical system presupposes an answer to a prior question, not what is true, but how truth itself may be known. Deism is no exception. Indeed, its distinctiveness lies as much in its epistemology as in its theological conclusions. Unlike systems that begin with revelation or authority as the source of knowledge, Deism begins with Reason itself, holding that any claim to truth must first withstand rational scrutiny before it may be accepted. Before one may argue for God, morality, or metaphysics, one must first establish the conditions under which knowledge is possible. The present essay therefore concerns itself with that prior inquiry, defending a particular account of knowledge as the indispensable foundation of the deistic worldview.
Conventionally, knowledge has been defined as justified true belief (JTB). This means that for any person to have knowledge, they must satisfy all three criteria regarding an idea they possess. For a person to hold an idea, they must hold a belief. For this belief to be knowledge, the belief must also be true. Holding false beliefs about the world isn't knowledge. However, it is the criteria of justification that often causes the most dispute. Knowledge cannot be sufficiently defined as merely true belief, because it is possible to arrive at a true belief but by the wrong method.
The Gettier Problem (and Gettier-cases) illustrate why justified true belief appears insufficient as an account of knowledge. For an illustration of Gettier cases, consider the following example: A man looks at a street across from his window and sees what he thinks is an ice cream truck. He makes the claim that there is an ice cream truck on that street. However, it turns out that the supposed ice cream truck he believed he saw was actually a taco truck. By coincidence though, there was a different ice cream truck on the street. Did the man in the example have knowledge? He held a true belief about reality, mainly that there was an ice cream on the street. However, while his belief is both true and seemingly justified by visual evidence, the link between his justification and the truth is entirely accidental. Had the second truck not been present, his belief would have been false.
In the prior example, the man had justification (seeing a ice cream truck), truth (there being an ice cream truck on the street) and a belief about the corresponding relationship between the truck and street. Despite this, most would be hesitant to grant that the man had the knowledge he claimed to have. The truth of his belief was accidental rather than the product of a reliable epistemic process. This is precisely the difficulty that Gettier cases are intended to expose.
This raises a profound epistemological crisis: if even a justified true belief can fail to count as knowledge, is certain knowledge even possible? Are we permanently marooned in the realm of mere intuition, unable to grasp reality? Surely not. While some philosophers conclude from Gettier cases that human knowledge is an illusion, such skepticism creates far more problems than it solves. Instead of abandoning the pursuit, this article will defend the criterion of justification, demonstrating that a refined version of the JTB framework can withstand Gettier’s challenge.
Gettier-cases are most effective in cases that require induction. An observation is made, and then an inference is constructed based upon that observation. The Gettier-case arises when this inference is incorrect but the underlying claim it makes is true. If one holds justifiable to be proven beyond certainty, then any empirical claim cannot be "justified". There are an impenetrable number of latent variables that can cause an induction to be incorrect.
Crucially, however, the vulnerabilities of induction do not imperil the entirety of human knowledge, as the epistemic landscape is not exclusively empirical. There are claims that are purely deductive or a priori in nature. Justifying such claims, if done through valid deduction and sound premises is apodictic. Gettier-cases cannot arise with these types of claims. Consequently, for a priori axioms, the classical JTB framework remains completely infallible. Empirical claims, by contrast, can never achieve this absolute justification; they belong to a separate epistemological category altogether, one forever confined to probabilistic distributions and degrees of confidence.
Followers of this website will be all too familiar with the key insight here and its major importance. Basing a world view on uncertain empirical claims (however probable they may be) comes with several shortcomings. This is especially significant for Deism. Any empirical argument for God is bound to be subject to inherent limitations that prevent its universal applicability. A deductive-a priori-axiomatic argument is the only hope for such a project. Going outside such bounds prompts the problem: How justifiable is your justification?
