Christians value truth pretty highly. In fact, we believe that we know the truth about who God is and what he has done. Sure, we don’t know everything about God, but a few key points are paramount for Christians. For example, the life, death, and resurrection of God’s son, Jesus. Now, some people doubt whether anything can really be known for sure, let alone anything about God. To them, any serious discussion about meaningful questions may seem futile. I want to rigorously show that such a priori agnosticism.¹The adjective “a priori” means being independent from experience or related to fundamental principles. Thus, self-evident beliefs, basic beliefs, and necessary beliefs can all be described as a priori. The belief of “agnosticism” says that nothing can be known, although the word is typically used in a more restricted sense to express that specific things cannot be known, such as whether God exists. is philosophically indefensible. (However, this post does not discuss how to get knowledge, only that you can. Later posts will address methods of acquiring knowledge.)

TL;DR

If it is impossible to know anything, then you cannot know for sure that knowledge is unobtainable. Therefore, it is possible to know something. If you don’t think my conclusion follows, then read on. My basic points are (1) that we cannot rationally deny the possibility of knowledge and (2) that we definitely can and do know some things.

Raising the attacker argument

Is it possible to know anything for certain? If human minds are fallible, doesn’t that mean nobody can ever be sure about any belief? After all, no matter how sure you think you are about something, isn’t it always possible that you made a mistake somehow? You could never absolutely rule out the possibility of error.

Not so long ago, this was precisely my thought process. I figured that knowledge was necessarily impossible due to the unreliability of the mechanisms for acquiring beliefs, namely the mind. Let’s refer to this as the “attacker argument”.²Note that this is more broad than the problem of perception, which restricts its discussion to knowledge of the physical world.

For this discussion, it is not necessary to concretely define “knowledge” since we are dealing primarily with our intuitions surrounding it. I tend to think of “knowledge” as “justified true belief”, although this definition may be a little too broad. So, I don’t want to waste time right now developing a robust definition of “knowledge”.

Now, the attacker argument given against the possibility of knowledge seems pretty valid. The only way it could fail is if it relied on some faulty premise. As a Christian, my scriptures commit me to affirm the reality of knowledge, so I am now going to offer a formal refutation of the attacker argument.

The defender argument

The first step of my refutation is to suppose this statement is true, “it is impossible to know anything”. Then, I will deductively show that this leads to a contradiction. Therefore, the statement is false and we can conclude that it is possible to know some things. Let’s refer to the following as the “defender argument”:

1. It is impossible to know anything.
2. It is impossible to know that all knowledge is unobtainable.
3. Nobody knows or can ever know that all knowledge is unobtainable.
4. It might not be the case that all knowledge is unobtainable.
5. It is possible that some knowledge is obtainable.
6. It is possible to know some things.
7. By contradiction, statement 1 is false.

Statement 1 is the conclusion of the attacker argument and the premise of the defender argument. Statement 2 is an instantiation of 1. Statement 3 applies 2 to restrict the capability of people. Statement 4 is a consequence of the epistemic restriction given by 3. Statement 5 rephrases 4 by flipping the negations. Statement 6 is just another way of saying 5. Statement 7 observes the contradiction between 1 and 6. Therefore, the conclusion of the attacker argument is false.

Objections to defender argument³If some of these objections don’t make sense to you, that’s fine. I just wanted to respond to as many objections as possible.

Objection 1: You equivocate metaphysical possibility with epistemic possibility.

This objection doesn’t work because my argument functions just fine with epistemic possibility in all instances of the term without needing to invoke metaphysical possibility at all.

Objection 2. You presuppose knowledge of the validity of logic, which must be discarded by the first premise.

This objection is a double-edged sword since the attacker argument also falls under it. So if you want to use this objection, the attacker argument becomes invalid and the defender argument becomes unnecessary.

Objection 3. The attacker argument is justified in presupposing knowledge of logic because it is part of a proof by contradiction, whereas the defender argument cannot likewise presuppose knowledge of logic because it operates under the conclusion of the attacker argument.

The attacker argument as currently formulated is not a proof by contradiction. But even if it was, your objection 2 is still a knowledge claim which violates the conclusion of the attacker argument. So, you cannot use it.

Objection 4. Statement 6 of the defender argument does not assert that some things are knowable, only that you can never prove that nothing is knowable. In other words, you have only shown that the conclusion of the attacker argument can never be rationally affirmed, not that it is false.

You are making a subtle distinction, and a good one. However, the fact that statements 1 and 6 of the defender argument directly contradict means that I have actually shown the conclusion of the attacker argument is false.

Objection 5. Objection 4 still works because it might be the case that we can never know which of statements 1 or 6 is true and which is false.

No, we can actually know that statement 1 is false and 6 is true for the following reason: If we assume 1 is true, then we can deduce that 1 is false. If we assume 6 is true, then 1 is false. Even if we begin without knowing which of 1 or 6 is true or false, we can use pure logic to deduce that 1 is false and 6 is true.

Objection 6. I think the weight of objection 4 still stands even though I may have worded it badly. Suppose I concede that the conclusion of the attacker argument is false. That only shows that knowledge is possible, not that we will ever actually know anything.

If knowledge is possible, then nothing necessarily prevents us from knowing things. However, I admit that people do not know everything that can be known. Thus, the possibility of knowledge does not imply the reality of knowledge, at least for specific things. The meaning of “possibility” in this context refers to the way it is used in the attacker argument, namely in virtue of human nature and its metaphysical restrictions. Whenever a person lacks knowledge of some knowable thing, it must be due to some conquerable circumstance. For example, if I punch some long expression into a calculator, I do not know what I will see as the result. If I press the “equal” button, I will know. If I never press it, I will not know. Sometimes, our knowledge depends on factors outside of our control. If the calculator died before evaluation, then I am prevented from knowing the answer. Likewise, another person could stop me from evaluating the calculation, preventing me from knowing the answer. Therefore, both impersonal and personal forces may prevent knowledge, but that does not have to be the case necessarily. So to answer your objection, because knowledge is possible, we are justified in seeking knowledge and working to conquer that which prevents knowledge.

End-notes

• 1
  The adjective “a priori” means being independent from experience or related to fundamental principles. Thus, self-evident beliefs, basic beliefs, and necessary beliefs can all be described as a priori. The belief of “agnosticism” says that nothing can be known, although the word is typically used in a more restricted sense to express that specific things cannot be known, such as whether God exists.
• 2
  Note that this is more broad than the problem of perception, which restricts its discussion to knowledge of the physical world.
• 3
  If some of these objections don’t make sense to you, that’s fine. I just wanted to respond to as many objections as possible.