Philosophers often discuss what beliefs are intuitive or counterintuitive to support their conclusions. I will argue that we should prefer theories and beliefs that are intuitive or sensitive to our intuitions rather than ones that aren’t.¹ The fact that a theory or belief is intuitive isn’t conclusive proof and a theory or belief being counterintuitive isn’t a conclusive disproof, but it is one important element when evaluating the plausibility of a theory or belief. Intuitive beliefs range from things we know with high degrees of confidence—such as “1+1=2”—to beliefs that are merely plausible enough to take seriously as “possibly true.” When a theory isn’t intuitive, then we call it counterintuitive, absurd, or revisionistic. Revisionism exists in degrees from not at all to totally counterintuitive. I will argue that we should prefer that our theories are intuitive rather than revisionistic for at least the following three reasons:

1. Language has limits and ordinary discourse greatly determines how our language connects to our understanding of the world. An extremely revisionistic use of language can completely fail to communicate properly and can become “off topic.”
2. We think we know things with high degrees of confidence without always being able to provide good arguments for those beliefs.
3. We can’t provide an argument for everything. We have to have some assumptions.

I have defended intuition in “Is Intuition Unreliable?,” but now I want to provide positive arguments in favor of intuition. I will (1) briefly discuss intuition and (2) argue that we should prefer intuitive beliefs and theories.

1. What is intuition?

Intuition is our unconscious ability to attain knowledge. It isn’t when we have a hunch, it isn’t popular opinion, and it’s not a supernatural power. The problem with intuition is that we often refer to a belief or theory as being “intuitive” when we don’t think we can provide non-intuitive evidence in favor of that belief or theory.² It’s hard for us to explain to others why we have certain beliefs despite our high degree of confidence. At that point we often hope they can agree how intuitive the belief or theory is.

An intuitive belief can be one that we think is strongly supported by an unconscious ability to attain “knowledge,” it can be necessary to explain our “knowledge,” or it can merely seem compatible with our “knowledge.”³ We have independent reason to accept intuitive beliefs in isolation when they are directly supported by intuition, but a belief that is merely compatible with our “knowledge” is much more speculative.

We would prefer that a belief be justifiable without the use of intuition. It’s much more clear why we should believe something based on observation than intuition because intuition is—by definition—an unconscious form of justification that is difficult to explain in words. Intuitive beliefs are not necessarily impossible to justify through non-intuitive forms of evidence, such as observation. Sometimes we can propose such non-intuitive forms of evidence to provide an argument in favor of our intuitive beliefs.

Many people dismiss intuition as “prejudice” because it is used to argue in favor of certain beliefs without entirely satisfying evidence. However, intuition has proven to be quite reliable upon occasion and I think it’s too demanding to expect all of our beliefs to be proven (through non-intuitive evidence).

We have good reason to expect that many of our intuitive beliefs would be difficult to justify through arguments and non-intuitive evidence. What we think of as intuitive evidence is not incompatible with other forms of evidence. In fact, many (or all) of our intuitive beliefs are actually based on an unconscious knowledge formation that considers those forms of evidence. Such a knowledge formation process does not necessarily map onto a simple argument that’s easy to communicate to others. Instead, it can be based on very complected forms of reasoning or even forms of evidence that can defy our ability to communicate. Consider the following forms of justification that I think our intuition can use other than observation⁴:

a. Self-evidence

A non-inferential form of evidence that doesn’t make use of arguments. Robert Audi argues that we grasp self-evident truths through sufficient maturity and “contemplation.” Self-evidence might not exist at all or it might only exist in the form of conceptual knowledge. We can know that some things are true by understanding concepts, like “2 > 1,” “1+1=2,” and “all bachelors are unmarried.” Self-evidence does not imply “obvious truths” or “innate ideas.” For example, we aren’t born knowing that “963/3 = 321” and it might not even be obvious to everyone. However, it is something we can figure out through time and understanding the concepts. Self-evidence, if it exists, isn’t always easy to describe because it isn’t a form of argumentative reasoning.

b. Instincts

What we understand or believe through instincts—if anything—would be expected to be advantageous to us. For example, children seem to recognize faces and understand some human psychology very quickly, and this understanding could very well be instinctual. If we know anything through instinct, then it’s not easy to defend through argumentation because it’s a product of our biology rather than reasoning ability.

c. Introspection

What we know to be true by examining our own thoughts, feelings, and experiences is not always easy to describe. How a thought feels or what it’s like to have thoughts is difficult to describe and it might be that we lack the words necessary to explain it to others. For example, how can we explain what it’s like to see green to someone whose never seen it? It might be impossible to communicate such an experience to such a person. No matter what we say, we expect that they still won’t quite understand. Introspection could be taken to be a form of observation, but it’s about what it’s like for us to exist rather than what it’s like to perceive something with the five senses.

d. Coherence

Sometimes we can reason that something is probably true because it’s compatible or necessary based on our current justified beliefs and experiences. It can be hard to fully justify a belief through coherence because there could be thousands of justified beliefs and experiences involved. For example, our belief that the future laws of nature will be the same (or extremely similar) as those in the past is necessary for thousands or millions of our other justified beliefs to be true—that the sun will rise tomorrow, that we can pick things up with our hands two seconds from now, that we will have bodies an hour from now, that bread will be nutritious rather than poisonous a week from now, and so on. To fully justify that the future laws of nature will be like those of the past through a coherence-based argument would take way too long.

e. Common sense

My definition of common sense justification is that we can indefinitely assume a belief is true until we have more reason to reject it than accept it. This is the justification we use when we have a working hypothesis—which is mainly what scientific theories rely on. A belief need not have any independent evidence to accept it, but it can still be reasonable to assume it’s true as long as the belief seems successful. Our assumption that the future laws of physics will be similar to those that exist now could ultimately require being a common sense assumption because it might be a justified assumption even before we attain a coherence justification in its favor. (A coherence justification in its favor could be viciously circular.⁵) What we assume to be true through common sense justification is often difficult to formulate into an argument because the assumption has been successful (and resists “objections”) in many ways and it can be difficult to list every single way that it’s been successful. There might be thousands of ways that a belief has been successful and thousands of “objections” that have been refuted through counterargument.

2. Arguments to prefer intuition to revisionism.

a. Intuition is sensitive to language

Proper use of language is based on our intuitive use of language, and language has philosophical implications. For example, when I say that I know that I have hands, I am (in part) proving that I know what the word “know” means to competent users of the English language. Anyone who argues that I don’t know that I have hands would seem to simply not know what “know” or “hands” are. We learn language in a great part by examples. People who learn what “know” means understands to tell others that they know they have hands and giving the wrong answer will be a great cause for concern. Sometimes our use of the word “know” is very important, such as when a police officer asks you if you know who the killer is. It would be inappropriate to say, “It’s impossible to know who killers are.” That would be a total failure of communication and perhaps a failure to even understand the police officer’s question. She wants you to answer in a certain way and you should understand that.

Philosophers who ask interesting questions like, “When is knowledge possible?” will often define what “knowledge” means, but that definition should be intuitive rather than radically revisionary. It should be sensitive to common examples of knowledge and how we use the word in everyday contexts. To prove knowledge is always impossible would require a radically revisionary definition of knowledge because the definition of knowledge is (in part) how we actually use the word in ordinary discourse including the examples we give of it. If a philosopher “proves that knowledge is impossible,” then we will think that philosopher doesn’t even know what the word means. The philosopher better tell the police officer who the killer is as an eye witness and not claim that eye-witnesses can’t possibly exist.

Also consider that water is H₂O by definition. We had an ordinary definition of water at one point based on how we use the word in everyday life by referring to the stuff that rains, is found in streams, is necessary to quench thirst, freezes at the North Pole, can be easily boiled using fire, and so on. We had to discover that H₂O is water by investigating the stuff involved when we use the word “water.” If a philosopher at some point gave a revisionary definition of water as oxygen based on the fact that oxygen is found whenever we point to water, then we would think that the philosopher completely misses the point. Oxygen isn’t going to quench our thirst or freeze near the North Pole.

Finally, consider how language has implications to the word “morality.” We can’t say that “killing people indiscriminately is always right” because what is considered to be right and wrong is defined (in part) through examples and one example of wrong behavior is killing people indiscriminately. Anyone who claims it’s not wrong wouldn’t know what “killing people indiscriminately” or “wrong” means—or they are using an extremely revisionary meaning for “wrong” that seems to totally miss the point. We could argue that they aren’t really discussing morality at all and they are actually talking about something else unrelated.

b. We think we know things even when we can’t argue for it.

Perhaps the best reason to believe in intuitive beliefs is simply because it’s intuitive to do so. Once we realize that we already accept uncontroversial examples of intuitive justification, we will understand why we have good reason to believe in intuitive beliefs and make use of intuitive justification. Consider the following examples:

2+2=4 – I don’t know how to prove simple mathematical facts through argumentation, but I think I know they are true. I suspect other people are like me in that regard. We have a high degree of confidence that “2+2=4” and will likely think that any argument in favor of such a conclusion will be less justified than the conclusion is anyway. People who argue that “2+2=4” is false or an unjustified belief are saying something striking that we would find absurd.

I know that I have two hands. – I think I know that I have two hands even though I could be in a dream world, and I have a high degree of confidence about it. I can’t prove with absolute certainty that my observation of my hands is reliable or that I’m not in a dream world, but I think think that both of these beliefs are very likely true. I suspect other people are like me in this regard. People who say that they don’t know they have hands are saying something striking that we would find absurd.

It’s wrong to kill people indiscriminately. – I think I know that it’s wrong to kill people indiscriminately even though I didn’t always know how to provide an argument for this fact and I think other people are like me in that regard. Now I think people or their experiences have intrinsic value and that value is lost when we kill them. Not everyone would agree with my explanation and there are others. It’s not absolutely clear whose explanation is right or if they are all wrong. Nonetheless, I think I know that it’s wrong to kill people indiscriminately with a high degree of confidence and any argument I come up with to prove it will be less justified than the conclusion it purports to prove. Again, people who argue that it’s not wrong to kill people indiscriminately are saying something striking that seems absurd.

An Objection: Isn’t it circular reasoning to justify intuition saying it’s intuitive? Someone could argue that my argument here is that “intuition is intuitive, therefore intuition is relatively reliable.” That argument is viciously circular. We would have to assume that intuition is reliable to prove it is.

My replies: First, we use intuition precisely when it is difficult or impossible to prove our justified beliefs through argumentation. Circular reasoning is a faulty form of proof through argumentation. I don’t claim that my argument proves that intuition is reliable, but I think it points out a good reason to think intuition is reliable. If I thought I could prove that intuition is reliable because it’s intuitive to think it is, then my argument would certainly be viciously circular.

Second, my argument is based on practical considerations—we have no choice but to use intuition for our arguments because we can’t prove everything in arguments. I develop this line of reasoning in more detail below.

Third, it’s not always clear what kind of justification is at work when we use intuition. It’s possible to justify one form of intuition with another. For example, I think some beliefs are justified just because they are successful assumptions and others are justified because they are coherent with other justified beliefs. The idea that some beliefs are justified for being successful assumptions is supported if we know that the belief that “we can use the past to learn about the future” itself is both justified and can only be justified as a successful assumption. In that case we can justify the use of common sense justification (successful assumptions) through a coherence justification.

Fourth, if intuition is justified through successful common sense assumptions (which could be experienced as a form of intuition), then the belief that “intuition is reliable” itself can be one of our successful assumptions. The belief that some justified beliefs are justified because they are successful assumptions might not need to be proven through argumentation because it might also be justified for being a successful assumption. That’s not circular reasoning because nothing would be proven through argumentation.

c. We can’t provide an argument for everything.

Even if any true belief can be justified by an argument in principle, that doesn’t mean it’s possible to actually provide an argument for every true belief. That would take forever. For every belief, we will provide an argument, and every argument requires us to accept at least one other belief that will also need an argument, and so on. To think that a real flesh and blood person is even capable of providing infinite arguments to justify a belief seems absurd because it would require infinite knowledge that makes the person capable of answering infinite questions. There are at least three ways we can avoid this problem:

1. We can justify our non-self-evident beliefs through self-evident beliefs that don’t need to be justified through argumentation.
2. We can justify our beliefs through coherence—including coherence with our observations and experiences.
3. We can justify our beliefs through successful assumptions. Such assumptions should be capable of positive and negative qualities that can compete with alternative beliefs, so that a belief can be rejected (unsuccessful) at some point. Some people would say that the belief should be capable of “falsification,” but that might be a strong word for what I am considering. (This is what I call “common sense justification.”)

What does all this have to do with intuition? First, intuition is used as a practical way to avoid arguing forever. We can take certain beliefs as “intuitive” and therefore justified until we have overriding reason to reject them.

Second, I don’t think every single belief can necessarily be justified through observation, coherence, or self-evidence; so I find it plausible that at least some justified beliefs are successful assumptions, which we often experience as being “intuitive beliefs.” Additionally, I think there are good examples of assumptions that are justified despite being in need of no argument—such as the assumption that “we can use the past to learn about the future,” and that assumption in particular does not seem to be self-evident or provable through observation. It might be partially justified through coherence, but I think the belief is justified prior to coherence because it should be an assumption we use in order to form all the beliefs it is coherent with in the first place—that bread will be nutritious in the future, that the sun will rise tomorrow, and so on.

Conclusion

Many people are dismissive to intuition and act like it’s too mysterious to take seriously. They want an argument for every belief and they want non-intuitive forms of justification. I agree that it’s preferable to have non-intuitive forms of justification, but that doesn’t mean intuitive beliefs are worthless prejudice. People who demand that we justify every belief through nonintuitive argument are too demanding and their world would be a strange one where there’s an argument for everything. That’s not a realistic way to live life. Much of our beliefs are based on an unconscious ability to attain knowledge and transforming that unconscious process into arguments is not always feasible.

I agree that intuition is fallible, but it’s still worth something. Nothing else considered, an intuitive belief is more justified than a counterintuitive one.

Update (3/31/11): I discussed an objection to my second argument for intuition and made some other minor changes.