Many ethicists agree that moral philosophy requires the use of intuition. My argument for moral realism itself requires the use of intuition. However, philosophers will require that we justify our use of intuition. Some philosophers have argued that intuition is too mysterious or unreliable to be used for philosophy. I will present the case that intuition represents our tendency to be unable to verbalize various justifications. I will explain how our intuitions makes use of relatively reliable justifications, consider four objections against intuition, and I will attempt to explain why the objections are not convincing.
Note that I am not an expert of intuition and I have read relatively little on the subject. Still, the little that I do know can clarify some issues people tend to have concerning intuitions, and I am able to respond to superficial objections.
What is Intuition?
Philosophers often speak of “intuition.” There is more than one meaning to the word, even in philosophy; but philosophers do not use the word “intuition” to mean “hunch,” “popular opinion,” or “extra sensory perception.” The word “intuition” stands for our ability to understand the world in a way that is difficult for us to verbalize. When scientists, mathematicians, or ethicists talk about intuition, they are referring to their ability to grasp which statements are probably true without being able to give an account of all the reasons and justifications for their beliefs. Here are five ways we can try to understand intuition:
- Intuition is our ability to grasp self-evident truths.
- Intuition is an instinctual process.
- Intuition refers to introspective evidence.
- Intuition is based on coherence.
- Intuition is common sense.
I will discuss each of these five sorts of intuition, and then the four objections to intuition.
Intuition is our ability to grasp self-evident truths.
A self-evident truth is something that we are justified to believe without additional justification. We can then speculate that we recognize that something is self-evident through some kind of intuition. Self-evident truths do not necessarily justify themselves, and they don’t necessarily lead to certainty. They merely assure us that not every justification must be justified because some justifications are justified through self-evidence. This helps us avoid an infinite regress. If every justification required a justification, then we would worry that no justification would ever be justified, and we could never have a fully justified belief.
Beliefs we believe are “self-evident” might be misidentified as such, but some beliefs seem to be very reliable without a further need of justification. How do we know “1+1=2?” We can know it just by thinking about it. Perhaps an understanding of the statement is enough to know it’s true. If so, intuition might be able to be an ability to grasp self-evident truths. On the other hand some philosophers believe that all mathematical truths are tautologies.1 Based on the definition of the numbers, we can know that the statement must be true. Denying the statement does lead to an absurdity, and that might be because denying the statement leads to a self-contradiction (the opposite of a tautology).
A supporter of self-evident intuition (also known as rational intuition) will argue that no argument is necessary to know that “1+1=2” is true and the meaning of the numbers are more than just definitions. Perhaps numbers can be defined with nothing other than logic, but that might be missing a more profound meaning that numbers have.
A supporter of self-evidence intuition might also argue that we could only endorse tautologies and reject contradictions given the fact that we have intuitions about tautologies and self-contradictions. We know through intuition that tautologies have to be true and self-contradictions have to be false.2 So even if mathematics can be reduced to logic (tautologies and self-contradictions), it still wouldn’t necessarily prove that we should reject self-evidence intuitions. They might even be necessary in understanding logic and mathematics.
If we know “1+1=2” through self-evident intuition, we might also know “torturing people for fun is wrong” in the same way. Just knowing the meaning of the words might be enough to know it is true.
Is self-evidence reliable? It is possible that we are mistaken about self-evidence entirely, but we really are certain some beliefs are true just by knowing what the belief consists of. “1+1=2” is a good example. We don’t need to be math majors making use of esoteric proofs to be sure that it’s true. If it’s not self-evidence, then we can call it something else. Either way, this kind of intuition is the most reliable sort of evidence despite the fact that no additional justification is required. We don’t need to prove such beliefs are true. However, self-evidence is not infallible. If we have identified a statement as being self-evident, we should be able to defend the belief.
2. Intuition is an instinctual process.
We might have some beliefs because of instincts. Our unconscious instinctual beliefs tend to be reliable enough to help us attain a reproductive advantage.
The belief that “1+1=2” could be one we immediately recognize to be true through our instincts. In a similar way some or all intuitive ethical beliefs could be justified in a similar way. We might all agree that cannibalism, incest, and necrophilia are wrong because of our instincts. Such behavior does not necessarily lead to real harm, but such behavior might have had a tendency to reduce one’s reproductive advantage throughout our evolutionary history. People who were repulsed by such actions might have then acquired a reproductive advantage. Some people have argued that ethics is somehow based on our instincts.3
The theory that ethics is based on our instincts is not completely arbitrary because morality might have a tendency to give us a reproductive advantage. There is a kind of trial and error involved. Additionally, instincts could be a guide to ethics without indicating moral anti-realism. An realist could admit that what has intrinsic value is also something we believe has intrinsic value due to the reproductive advantage involved.
One could object that evolution could lead to delusional beliefs whenever doing so would lead to a reproductive advantage. We don’t want to exclusively justify our beliefs “just because they are useful to us” because we might then live in denial and choose to be delusional. I agree with this objection. However, the belief that “1+1=2” might be instinctual without being delusional, so it is quite possible for instinctual beliefs to be a reliable source of knowledge in general.
Instincts are generally reliable or we wouldn’t have them. However, they are not infallible. It is also plausible that some people have different instincts than others. (Perhaps some sociopaths lack an instinct to value other people.) Instincts can be questioned and some additional justification for instinctual beliefs should be available in order to resist our doubts.
3. Intuition refers to introspective evidence.
Some beliefs are intuitive because they are based on our introspective evidence. We have a difficult time verbalizing and justifying introspective evidence, just like we have a hard time verbalizing and justifying our “intuitive beliefs.” It could be that many of our intuitive beliefs are actually based on introspection. The belief that “pain is bad” might not simply be self-evident, but it might be immediately evident upon our experience of pain. We can then contemplate our experience of pain in order to know whether or not our belief that “pain is bad” is justified through the experience.
My argument for moral realism requires the use of introspection, and the “intuitive evidence” that I use might actually be based on nothing other than our experience of morality. Our experience of pain might justify our belief that “pain is bad” and knowledge that other people experience pain in the same way could justify our belief that “pain is bad for no matter who experiences it.”
There is also an attempt to verbalize our introspection in phenomenology, and the view that intuition is based on introspection, is similar to Henri Bergson’s view, who argues that we can attain knowledge through self-sympathy.4
Some philosophers discuss “perceptual intuition,” which might also be a kind of introspective intuition. We have a perceptual intuition when we see a red apple, that the apple is red. We know it immediately from the experience. In a similar way, we might immediately see that “1+1=2” is correct through our experience of seeing it, and we might know that “pain is bad” is true through our experience of pain. I technically believe something more is happening in the mathematical and pain examples than “perception,” so this liberal interpretation of perceptual intuition might include any sort of personal experience that allows us to know something immediately upon seeing it, thinking it, or experiencing it in some other way.
Is introspective evidence reliable? If we have a perceptual intuition of mathematical and logical truths, then yes. Introspective evidence is also the way we know about thoughts and perception in the first place, which is very strong evidence that there are thoughts and perceptions.
4. Intuition is based on coherence.
Some beliefs are intuitive because they cohere with our unexamined beliefs, observations, and introspection.
Intuition based on coherence is the kind David O Brink defends in his book, Moral Realism and the Foundations of Ethics.5 Scientists might have “scientific intuition” based on his or her other beliefs. Once a scientist has been sufficiently introduced to scientific facts, a kind of scientific world view might emerge that makes scientists able to predict yet-to-be-discovered scientific facts. This ability could be improved by further knowledge of scientific facts. This kind of knowledge might be a lot like what Aristotle thought of as practical wisdom. A belief could be justified through coherence without explicit verbalization. This kind of intuition might be important for theoretical physicists, such as Einstein, who could hypothesize about the nature of the universe with remarkable accuracy.
Perhaps mathematical and ethical intuition could also be justified in this way through coherence intuition. Knowing more mathematical facts can help us immediately recognize more mathematical statements to be true. We might all immediately recognize that “1+1=2” but only an expert will immediately recognize that “2938234+34234 =2972468.” In a similar way unconscious ethical beliefs might be improved when one acquires ethical expertise.
Coherence theorists have to be able to tell us how we should decide which belief should be rejected whenever there are two or more beliefs that contradict. One solution is that some beliefs have a greater power of coherence than others. If one belief is required to justify five of our other beliefs, it would have a greater coherence power than a belief that justifies three of our beliefs. (This is an over simplification of what we actually have to do, but it’s the general idea.) If two beliefs contradict and no other beliefs are relevant, then it might be impossible to decide which belief to reject.
Consider the following beliefs:
- We have an afterlife.
- Our existence has intrinsic value.
- Murder is wrong.
Of these beliefs the first seems incompatible with the other two. It makes sense to say murder is wrong if our existence has intrinsic value (and given the fact that our existence is mortal). However, we have a choice: Should we reject that we have an afterlife or should we reject that murder is wrong? It makes the most sense to reject that we have an afterlife than to reject that murder is wrong because we are much more certain that murder is wrong than the immortality of the soul.6
Is coherence intuition reliable? If scientists have a kind of scientific intuition based upon unconsciously held beliefs and coherence, then yes. It is true that coherence is not infallible and some people’s coherence intuitions are different, but experts have better intuitions than non-experts. Coherence intuition is evidence that something is true, but the results of intuition shouldn’t be taken to be anything close to certainty without further investigation. Further investigation could be an attempt to verbalize that which was on first examination too difficult to verbalize: We need to figure out why we find certain beliefs so intuitive, or we need to investigate whether or not our intuition is correct through observation and/or introspection.
5. Intuition is common sense.
Some beliefs are intuitive because they are based on successful unconscious assumptions. These assumptions should be defensible. We might not be able to prove common sense assumptions are true, but common sense requires that there be no overriding reason to reject them.
There are different levels of justification common sense assumptions can have. All common sense assumptions should cohere with our beliefs just as much as the alternative. (Sometimes neither a belief nor its negation will perfectly cohere with our other beliefs.) Some common sense assumptions are highly justified because the assumption is in some sense necessary. Common sense is open to the possibility that observation, self-evidence, coherence, and/or introspective evidence are all relevant when deciding whether or not a belief is “necessary.”
Consider the following 3 examples of common sense intuition:
Example 1: It might be necessary to understand the world by assuming that inductive reasoning is effective. We could argue that we might not be able to prove that inductive reasoning is effective, but denying that it is leads to the absurdity that empirical knowledge becomes impossible. Gravity might stop working tomorrow, but that is very implausible. Our belief that gravity will keep on working is one of our most reliable beliefs, but the belief is only justified if inductive reasoning can be effective.
Example 2: “1+1=2” might be justified by common sense because we rely on the truth of the statement for so many other things in our lives. For example, lots of mathematical truths depend on the fact that “1+1=2,” so we need to assume its truth in order to assure that our other mathematical beliefs are justified. If “1+1=2” is false, it leads to the absurdity that other mathematical statements we know are true would also have to be considered to be false.
Example 3: Ethical statements might be justified through common sense. “All things equal, causing pain is wrong” might have to be assumed to be true in order to justify several of our other ethical beliefs, such as “torturing people for fun is wrong.”7
Coherence theorists sound a lot like they endorse what I have described as “common sense” because if they agree that we need our beliefs to cohere with our observations and introspective evidence. However, there are two differences between common sense and coherence. One, common sense assumptions can be rationally permissible as long as there are no overriding reasons to reject them, but coherence generally demands that a belief be justified through evidence of some sort. Two, common sense assumptions could admit that some beliefs are self-evident, or something a lot like being self-evident. Some beliefs are very plausible whether or not we have additional justification for that belief in the form of coherence, introspective evidence, or observation.
One reason that coherence alone might have to take a back seat to common sense is that it might be unable to appropriately decide which of two contradictory beliefs to reject. Only one belief might need to be rejected and we should reject whatever belief is less plausible. How do we know if a belief is plausible? We can consider our observations, introspective evidence, and/or self-evidence. In particular, coherence theorists don’t accept self-evidence. Consider the following three beliefs:
“1+1=2” contradicts the other two beliefs. However, “2+2=3” might cohere with “4+4=6.” Someone who had more beliefs that cohere with “2+2=3” might use coherence to reject that “1+1=2.” Coherence in this situation might not be a good way to decide which belief to reject. Instead, self-evidence might be more appropriate. The belief that “1+1=2” is one we are certain is true even if we hold beliefs that contradict with it. All beliefs that contradict with such a self-evident truth should be rejected.
Is common sense intuition reliable? Some people’s common sense differs from others’, just like coherence intuition. In that case two different people might disagree about what is “intuitively true,” and they both might be permissibly justified to have their belief. I admit that common sense does not indicate absolute reliability. However, an expert’s common sense (or good sense) is relatively reliable. The results from common sense intuition are worth further investigation, just like coherence intuition. The results of common sense intuition must be defended, and some assumptions will prove to be much more reliable than others.
2. Objections to Intuition
The arguments against intuition wish to prove that it is unreliable. Here are different reasons people try to reach that conclusion:
- Intuition is just popular opinion.
- Intuition is mysterious.
- Different people have different intuitions.
- Intuition can’t be justified without vicious circularity.
Intuition is just popular opinion.
Either some people misunderstand intuition as being nothing more than “popular opinion,” or we could find out that intuition really is nothing more than popular opinion. We didn’t want intuition to just be popular opinion, but maybe it is anyway.
The main reply to this objection is to merely take another look at the kinds of intuition that I have already discussed: Intuition can refer to self-evidence, instincts, introspection, coherence, or common sense. Once we talk about these forms of evidence rather than “intuition,” it is pretty clear that we aren’t just talking about popular opinion. Coherence might be a lot like “popular opinion” for many people, but coherence for an expert is a lot more sophisticated than the coherence for everyone else.
A philosopher might reject self-evidence entirely, but whatever is happening instead of self-evidence is a very reliable kind of evidence. Intuitions are not infallible, but the results warrant further investigation.
Intuition is mysterious.
The charge that intuition is mysterious is mainly a charge against self-evidence or innate ideas.8 I have four replies against this objection. First, whatever we believe to be “self-evident” tends to be very plausible.
Second, there are at least four other kinds of intuition other than self-evidence, which are not mysterious.
Third, it is true that intuitions tend to be difficult to verbalize, but this merely indicates that a kind of unconscious practical wisdom is at work. Not all justified beliefs are easy to explicitly defend to other people. That doesn’t in itself prove that such beliefs are unreliable.
Fourth, intuition (even of self-evidence) is not necessarily evidence of “innate ideas,” which was Descartes’s explanation for some intuitive knowledge. Innate ideas are God-given concepts or truths, such as the concept of perfection. I agree that innate ideas might not exist. However, intuitions can be quite reliable with or without innate ideas.
Different people have different intuitions.
I already admitted that different people have different intuitions. This is especially true of coherence intuition, in which experts have more reliable intuition than the rest of us. Disagreement concerning intuition can prove that intuitions are fallible, and I would admit that even the intuition of experts is fallible. However, intuition is reliable enough to be worth further investigation. When it comes to science we can test the intuitions through observation. (More specifically, using a hypothesis and experiment.) When it comes to ethics we might make use of introspective evidence and observations. For example, our experience of pain gives us important evidence that “all things equal, it is wrong to cause pain.”
Richard Joyce argues that people’s actual intuitions have not been sufficiently examined by scientists, and such intuitions are merely anthropological facts.9 This might be true of instinctual intuitions, which are probably reliable to some extent, but there are kinds of intuition that are even more reliable. In particular, expert coherence intuitions are more relevant than the intuitions of other people. Why would a philosopher need to know which intuitive beliefs are most common? Intuition isn’t meant to provide us with an ad populum argument.10 Although knowledge of instinctual beliefs could be somewhat relevant, the coherence intuitions of experts tends to be much more relevant than the opinions of everyone else.
Intuition can’t be justified without vicious circularity.
In “The Problem of Intuition” Stephen Hales argues that intuition can’t be justified without the use of intuition.11 Therefore, intuition can’t be justified without vicious circularity. I believe that he means “intuition of self-evidence” by the word “intuition,” so his argument appears to be saying that self-evidence can’t be justified without self-evidence. I am not committed to the existence of self-evidence, but I will give three responses to his objection of circularity:
- If we accept that there are self-evident truths, then haven’t we already avoided circularity? We don’t need to justify a self-evident truth because it is self-evident. They are justified just by understanding them. Hales argues that self-evidence must be axiomatic or it’s entirely unjustified. Perhaps I just don’t understand his argument, but I thought the whole point of self-evidence was that they are justified for free.
- I am not convinced that we do need intuitions of self-evidence in order to justify the use of intuitions of self-evidence. There are other kinds of intuition other than the self-evident variety, and those intuitions could justify self-evidence.
- Intuitions other than the self-evident variety can be verbalized in terms of observations, introspection, coherence, instincts, and common sense. Therefore, we might find a way to justify self-evidence in terms of these other forms of justification. For example, common sense could dictate that we could assume that intuition is a reliable form of justification as long as we can defend such an assumption. Rejecting self-evidence might lead to the absurdity of rejecting logic. If that is the case, then self-evidence is necessary for every kind of justification possible and we would have to reject the possibility of knowledge despite the fact that we know at least some of our beliefs are true.
I could be wrong about what he means by “intuition.” If he literally means that every kind of intuition can’t be justified without intuition, then I can still reject his argument because “intuition” can mean different things. There’s nothing viciously circular about justifying one kind of evidence with another kind of evidence. For example, we might know that “murder is wrong” based on a coherence justification.
The problem of intuition stated here appears to actually describe the huge problem of epistemology in general:
How can we know what knowledge is? Any answer to this question seems to lead to vicious circularity. (Wait. Are you sure you know that’s what knowledge is?) For example, if all knowledge is empirical, then how can we justify that? Do we observe that all knowledge is based on observation? That would be circular reasoning. (Assuming observation is reliable, we can observe that it exists.) You get the idea.
There are three ways we can try to know what knowledge is:
- Use an infinite regress. We can justify what knowledge is, and justify that justification, and justify that, and so on.
- Use circular reasoning. We know that knowledge is X, and we know X is knowledge because it is X.
- Use a self-evident truth.
Of these options, the third appears best given our current options, but philosophers have tried all three possibilities, which corresponds to infinitism, coherentism, and foundationalism. Hales decides that we must either be foundationalists or reject intuition (and therefore most or all of philosophy), but we should consider all three of these theories:
Infinitism: Justifications can be justified indefinitely. We will never be done justifying beliefs because every justification can also be justified.12 It might be permissibly rational to believe something as long as it is currently the best option available. We can start off with assumptions without justifications, and we only reject our beliefs when they are “falsified” (or at least implausible considering that there are better alternatives.) Some assumptions are necessary, but we can reject assumptions when they become unnecessary. This view of epistemology is similar to Karl Popper‘s.13 Some people say that this view requires an infinite regress, but that would require us to accept that no belief is justified unless the justification is also justified. Some beliefs can be rationally held without a justification. The common sense theory of knowledge might not fully justify absolute knowledge because all justifications might rely on assumptions.
Coherentism: Beliefs are justified depending on how important they are for coherence. This view allows circularity. Some beliefs are justified by other beliefs, and our whole worldview as a whole can then be used to justify our beliefs. Coherence is circular because every belief can be considered to be a partial justification for every other belief it coheres with. We could then imagine that A justifies B, B justifies C, and C justifies A. Coherence avoids an infinite regress because only a set of coherent beliefs is necessary to have a maximally justified belief. The coherence theory of knowledge doesn’t justify absolute knowledge because beliefs are not completely proven to be true.
Foundationalism: Some beliefs are self-evident. We avoid circularity because we just know that something is true without any other justification required. We also avoid the problem of requiring an infinite regress because self-evident truths stop our need to justify justifications.
Hales seems to assume that all beliefs must be justified, but we can be rational by holding some nonjustified beliefs. There is a difference between beliefs that are rationally permissible and beliefs that are justified. Beliefs are rationally permissible as long as they aren’t incoherent (and as long as there aren’t overriding reasons to reject them). Beliefs are justified when we have evidence that they are true (and as long as there aren’t overriding reasons to reject them). Absolute knowledge might require foundationalism, but we might live our lives without absolute knowledge. Instead, we could just admit that epistemological justification is possible, some beliefs are more justified than others, and some beliefs are very accurate. (Science has proven that it can be very reliable despite the fact that it is always willing to improve.) Once absolute knowledge is rejected, coherentism and infinitism will be acceptable theories of knowledge.
When we give intuitive evidence, we generally show that a theory of belief is absurd based on our intuitions, or that we must agree to a theory or belief because rejecting the theory or belief would be absurd. Such absurdity is based on our unconscious understanding of various kinds of justification; such as self-evidence, instincts, introspection, coherence, and common sense.
These five sorts of intuition are not infallible, but they can indicate a very strong justification that something is true. (This seems especially true for introspective evidence and self-evidence.) Although our intuitions are difficult to verbalize, sometimes we can verbalize them in order to provide an explicit justification for our intuitive beliefs. One of the least reliable forms of justification might be common sense intuition, but even common sense assumptions are (at least) rationally permissible (unless we have an overriding justification to reject them).
The use of intuition to provide us with self-evidence might allow us to attain absolute knowledge, but philosophers don’t have to accept that absolute knowledge is possible. The other forms of intuition only provide us with at least enough justification to warrant further investigation. Sometimes intuition can shift the burden of proof by providing one possibility with more evidence than the alternatives.
1 Something is a tautology if it is logically impossible for it to be false. For example, “Humans are apes or they are not apes.”
2 A logical system could theoretically endorse contradiction by rejecting the principal of non-contradiction. We need a way of knowing why one logical system is superior to another.
3 Stoic philosophers accepted a very similar view.
6 Note that these beliefs are just used for demonstration, and I have not provided a serious argument that we should reject the immortality of the soul.
7 If “all things equal, causing pain is wrong” is false, then we might be lead to the absurdity that we would have to admit that other strong ethical beliefs, such as “torturing people for fun is wrong,” would no longer be justified.
8 Innate ideas were discussed by Rene Descartes in his Meditations. They are truths we know as soon as we are born.
9 Joyce, Richard. “Is either moral realism or moral anti-realism more intuitive than the other?” Stanford Encyclopedia of Philosophy. 19 Jan. 2010. <http://plato.stanford.edu/entries/moral-anti-realism/moral-realism-intuitive.html>.
10 An ad populum argument attempts to prove something just because most people believe it. Of course, such an argument can prove that many people believe something. However, it can’t prove much of anything else.
11 Hales, Stephen. “The Problem of Intuition.” American Philosophical Quarterly, volume 37, number 2, 2000. 135-147. (Bloomsberg University of Pennsylvania. 18 Jan. 2010. <http://departments.bloomu.edu/philosophy/pages/content/hales/articles/intuition.html>.)
12 This is the result I expected philosophers to accept when I first learned about philosophy, and I don’t think it’s entirely implausible.