Lucretius defends the idea that knowledge can be obtained by the senses alone. In this paper, I’m going to challenge Lucretius’ contention that knowledge can be obtained by the senses alone without the use of reason. We should not conclude that the knowledge could be sufficiently gained by just using the senses because such an approach is unreliable, and conclude that knowledge can be obtained sufficiently by reason alone or reason plus the senses because this is a reliable approach.
The first contention is that there are good reasons to think that knowledge can’t be obtained only from the use of the senses. If knowledge can be gained only from the senses alone, then knowledge isn’t reliable. Why think this is the case? Well if knowledge is derived from purely the senses then what is to judge whether our sense perceptions are true? If Lucretius somehow said “reason” wouldn’t that be circular? Because reason at best wouldn’t be necessary or sufficient on his view, similarly it would still be the circular if someone said senses in themselves because that’s the very point you’re starting with! So then if knowledge itself isn’t reliable then Lucretius’ account is literally epistemologically self-refuting. If we’re not rationally justified in believing that knowledge is derived from the senses, then of course we should give up the belief itself that knowledge arises from the senses!
Furthermore, if knowledge can be obtained solely by using the senses, then why do we falsely conclude things from our senses? If we think about things like hallucinations, we’d wonder if that would reasonably happen if reason were derived from the senses. Well it seems to me that this isn’t the case. We can think of cases where someone claims to have seen Superman or Captain America, but in turns out the person is a drug addict who is known for seeing things that are not actually there in reality. In other words, it’s a projection of the mind instead of existing objectively in the external world. Another case is if Jones hears a lion roaring, while he may be justified in believing it, unbeknownst to him he’s hearing the roar because he’s really sleep deprived and hasn’t slept in 3 days.
Lucretius seems to have response to the objections to hallucination, etc. The answer is that reason itself would be responsible for our misinterpreting of things in the external world or hallucinations. But this seems patently ridiculous once you think about. There are many things that appear immediately that aren’t even processed by my brain. There is no interpretation. And there are various things in which I could use my reason to dissect what I am looking at but still reach the false conclusion! For example, the classic sticks in the water analogy. I’m not using a deduction in my mind to know that is seems to me that a stick is crooked. Rather, I’m having an immediate experience of a crooked stick.
Next, if knowledge can be obtained purely from the senses then how did we arrive at the proposition “all knowledge is obtained purely from the senses”? I don’t see how we can test the proposition with our senses. So this sort of epistemology is literally self-defeating. Not only that, but it’s also too restrictive. There are all sorts of propositions that aren’t from the senses. There’s no possible world, including the actual world, where a square-circle exists. This is derived from sole reason, not from experience. And such truths are true regardless if we experience these truths or not, in other words they are objective.
Knowledge is best accounted for if reason is a necessary element to obtaining knowledge. which is to say that it, knowledge can’t be gained from just the senses. Alone. There are few reason to think that this is the case. Knowledge with reason as a necessary criteria accounts for innate ideas. There seem to be at least a couple of innate ideas that we possess prior to experience. As a kid, I knew that something couldn’t come out of nothing, even though I had never been socially conditioned to do so or had sense perceptions of such thoughts. Also, a lot of philosophers think that moral principles are innate within each human mind. These are present at birth, thus this makes sense of kids who feel bad and know that certain things are wrong like murder, prior to coming across such an experience. How can we experience morality from our senses? This doesn’t seem to make much sense. I could agree that maybe some cases we seem to gain awareness of what is wrong from our experience but that this could ultimately just point back to our moral intuitions. In other words, we are still ultimately using our moral intuitions. So it doesn’t seem that the a strict empiricist can have good account of innate ideas that has explanatory power or explanatory scope. They could very well just bite the bullet and say that we don’t have innate ideas at all.
Furthermore, we seem to have thoughts of abstractions that can’t be experienced from the senses such as 1+1=2 or A=A. Have we experienced such things? Well it seems that this isn’t the case. Now the obvious objection for Lucretius could be that this rationalistic approach is circular in itself. But my contention is that we aren’t use reason to prove reason. Rather we have bedrock or foundational beliefs that are self-justifying. For example: A is not ~A., A or A, I exist, and if A=B, And B=C, then A=C. These are rational/logical laws that are prior to our experience and prior to our existence.
Thirdly, knowledge that includes reason as necessary sets the foundation of all natural science. Science assumes logical absolutes and rules. But these can’t be done without a mind applying these concepts in science namely, a Scientist. If these logical laws are discovered then we can’t have a start for Science. Rather these have to be assumed prior to doing science. And the only way this can happen is if we are already aware of these prior to experience. Otherwise, we have an unreliable foundation because it’d be circular.
Another common objection could be, “how do we know which truths are innate and intuitional?”. But this objection seems to be confusing the ontology of truth and epistemology of truth. We can know that innate ideas exist without knowing which ones count as actually innate ideas. I know that I exist without knowing the exhaustive list of innate ideas, and I don’t know how one would go about giving an exhaustive list! Furthermore, I can know that certain things are wrong without knowing why they are wrong, so its seems rather obvious that we can know a lot of things without being aware of why it is the case. Even more so, we can have innate ideas in our mind, even if we don’t know what an innate idea is. Lucretius could come up with an objection that knowledge based off experience is simpler than appealing to innate knowledge. But this seems to ignore what Ockham’s razor means for the rationalist because the rationalist is saying that the empiricist approach needs more entities necessarily because it can’t account for things like innate knowledge. So an empiricist like Lucretius is the one who bears the burden of proof if he is going to say that rationalism is imparsimonious. It would first have to be shown that empiricism necessarily is the only idea that needs to be postulated in order to account for knowledge.
But notice that someone like a rationalist doesn’t have to say senses + reason. They could simply stop at just reason-That every single piece of knowledge is based off reason. Although, I myself wouldn’t necessarily defend such a position because I do think the senses are necessary in gaining certain pieces of knowledge that couldn’t be obtained by reason alone, which would include things like the appearance of colors or objects. In addition, it’s not logically incoherent to say that knowledge based off of reason that is prior to experience. To suggest otherwise without evidence is simply begging the question. A priori knowledge doesn’t match well with an empiricist world-view, but they still need to give an argument if they disagree that there’s not this type of knowledge.
Finally, I want to address one final objection. The objection says that there is no universal innate ideas when we examine the people in the word. But I don’t see any problem with this supposed universal agreement objection. It could very well be the case that some ideas are only innate for certain people. However, that does literally nothing to show that there aren’t at least a couple of ideas in all humans that are innate. But, even if there weren’t universal agreement that certain ideas like “X” not being an innate idea, it wouldn’t follow that it isn’t indeed an innate idea. The person disagreeing could be confused, mentally ill, or lying. Therefore, it seems obvious the concept of things like innate ideas and moral intuitions if they exist, would necessarily defeat Lucretius’ doctrine of empirical experience being the necessary and sole sufficient condition for knowledge.