The Appeal to Intuition: A Fallacy?

You might be familiar with what philosophers call an “appeal to nature“. It is a claim that something is good or right because it’s natural. Sometimes an appeal to nature is a fallacy. In this post, I discuss the possibility that an appeal to intuition is that kind of fallacy.

1.  Different Brain, Different Intuition

First, imagine that your brain and my brain are radically different from one another. If this were the case, then it would be unsurprising to find that your intuitions were different than mine. Indeed, evidence suggests that even minor differences between brains are linked to differences in intuition (Amodio et al 2007Kanai et al 2011).

This implies that our appeals to intuition (etc.) might be contingent upon brains being a certain way. In other words, differences in intuitions seem to be the result of differences in natural properties.†

2.  The Appeal To Nature

It is not difficult to find an appeal to intuition in philosophy. For example,

The idea that [P] is so intuitive that most will need no more proof than its statement (Wenar 2008, 10).

But what is going on when philosophers appeal to intuition? What makes something intuitive? Does intuition track truth? Reliably? Approximately? Or does it track something else?

If it tracks something other than truth, then our intuitions will change even if the truth does not. And, like I mentioned last week, some of our intuitions seem to change when our brains change. But changing our brains would not change what is true. So at least some of our intuitions do not seem to track truth. They seem to track something else — something about the nature of our brains.

Suppose that moral intuitions do not track truth. They might only track features of our brains. For instance, most people have an intuition that it is bad to harm people when the harm can be avoided. But if this intuition is merely the result of our having certain neural properties, then it is not clear that the intuition is true. Just because the intuition is widely shared doesn’t mean it’s correct. After all, if we changed everyone’s brains in a certain way, then maybe we would change our intuitions about harm (Crockett et al 2010; Crockett et al 2016).

3.  Explanation ≠ Justification

While natural properties can help us explain our intuitions, they do not justify them.†† This becomes more clear when we consider counterintuitive claims.

Some people try to show that utilitarianism is counterintuitive by pointing out that psychopaths are more likely to make utilitarian judgments (Bartels and Pizarro 2011).††† But it’s not clear how that amounts to an argument against utilitarianism. After all, the difference between our moral intuitions and a psychopath’s moral intuitions might be just a difference in brains (Glenn et al 2009, see also a response from Koenigs et al). So contrasting our intuitions with psychopaths’ intuitions ends up looking a bit like an appeal to nature. It appeals to the nature of neurotypical brains.


“Not so fast!” you might say. “Why should we think that the difference between me and a psychopaths’ intuitions is only a difference in brains? There are other differences. Namely, there are arguments that undermine psychopaths’ intuitions more than my intuitions” (this kind of response can be found in Deutsch 2015).

There are a couple claims here so let’s take them one at a time.


First, a concession. Neuroscience is far from fully explaining the differences in our intuitions. So it wouldn’t be surprising if there is more to our intuitions than what neuroscience tells us. Also, it’s not even clear that neuroscience can fully explain our intuitions.

Second, let’s think about those arguments against the psychopaths’ intuitions. What makes these arguments compelling? Is it similar to what makes something intuitive? What if the appeal of arguments — like intuition — can be explained by natural properties of our brains? If this is the case, then the mere existence of compelling arguments for an intuition doesn’t necessarily justify the intuition. It might only provide a post hoc rationalization of the intuition (Schwitzgebel and Ellis 2016).


It’s not obvious why one set of intuitions are supposed to be better than another set. Science reveals only that certain brains (normal brains, philosophers’ brains, etc.) produce certain intuitions (Kahane et al 2012). But that does not necessarily justify intuition. (And it doesn’t necessarily debunk intuition either.)

4.  So Is An Appeal To Intuition A Fallacy?

It seems pretty clear that our intuitions can depend on nature — e.g., on our brains being a certain way. So an appeal to intuition can be an appeal to nature. And an appeal to nature can be a fallacy. But that’s not enough to conclude that every appeal to intuition is a fallacy.

So the short answer to our question is this: not necessarily.

Longer answers will fall into at least three categories

  1. The necessary justification category: “No. Intuitions are justified because they are intuitions (and not because they are ubiquitous, reliable, useful, etc.). That is, intuitions are necessarily justified.”
  2. The contingent justification category: “No. Intuitions are justified because of some accidental feature of intuitions (e.g., their ubiquity, reliability, utility, etc.). So intuitions happen to be justified, but they aren’t necessarily justified.”
  3. The unjustified category. “Yes. An appeal to intuition is a fallacy because intuitions are not justified. They are only apparently justified. But when we study intuitions, we find that intuitions are the result of natural (neural) properties — nothing more. And, contra the appeal to nature, natural properties do not necessarily justify.”

I haven’t argued for any of these answers. I have merely tried to show that it’s not obvious how our intuitions can be justified. So you might wonder how you can argue for some of these answers.

5.  The Self-Defeat Argument

The Self-Defeat Argument might be the easiest way to argue that intuitions can be justified. It’s pretty simple. The most important premise is this: if intuitions aren’t justified, then nothing is justified (Huemer 2001, 107-8). The full argument goes like this:

…the rejection of [intuition] is self-defeating, roughly, because one who rejected [intuition] would inevitably do so on the basis of [intuition]. […] Therefore, if this opponent of [intuition] were right, his [rejection of intuition] would itself be unjustified. (Huemer 2007, 39)

Sounds intuitive, right?

Well, before you get too comfortable with the Self-Defeat Argument, you should know that some philosophers don’t buy it (DePoe 2011; Mizrahi 2014). So if you want to accept the Self-Defeat Argument, then you might want to see how you can respond to those philosophers (Huemer 2011; Huemer 2014). And then you might want to see a counter-response (Mizrahi 2014).

Closing Thoughts

So what do you think? Are intuitions justified? How? Why? How can science help us answer that question?

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† Notice that I did not say “only the result of natural properties.”

†† Notice how I didn’t say “fully explain our intuitions”.

††† I’m not saying that Bartels & Pizzaro do this. I’m saying that people appeal to Bartels & Pizzaro’s study to do this. Ibid.

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Nick Byrd

Nick is a cognitive scientist at Florida State University studying reasoning, wellbeing, and willpower. Check out his blog at

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John Fapo
John Fapo
Thank you for the excellent survey of this interesting topic, and for the bibliography you provided. My personal view on intuitions has always been this one: we must, for practical reasons, stop the chain of justification at some point. Intuitions can play this role, and we have the right to consider them to be provisionally true until someone proves otherwise, and replaces the contested intuitions with new ones. And so on, ad infinitum. Intuitions are only there for practical reasons, and should be taken only as provisionally true. This is similar to the self-defeating argument, so I will enjoy reading… Read more »
I think you’re onto somethings that parallels what I’ve been thinking about recently. Let’s, for the length of this comment, reverse things a bit. Suppose that the brain is instead built from from intuitions. That from the beginning of our lives as human beings, we each have different kinds of intuitions that influences how each of our brains gets structured and built around. Because really, what are intuitions? I believe they’re the intersection between all the information our brain processes that somehow makes enough “sense” for the subconscious to pass onto the conscious without the ability to transfer the vast… Read more »
Angra Mainyu
Hi Nick, It’s an interesting argument, but I’d like to raise a couple of objections. What about epistemic intuitions? For example, let’s say Bob is a Young Earth Creationist (YEC), but he is consistent. Since theory is (at least nearly always, and definitely when it’s about empirical matters) underdetermined by evidence, he consistently believes that YEC is true. He accepts all of the observations made by scientists, but interprets them as Lucifer planting fossils to tempt us, or Yahweh doing so to test us, etc. Now, imagine that his brain is wired radically different from yours, and he’s just assessing… Read more »
Angra Mainyu
Hi Nick, The targets would be the arguments based on brain differences and the analogies with the naturalistic fallacy in support of the hypothesis that the appeal to intuitions is a fallacy, and/or that the appeal to intuitions lacks epistemic justification or is otherwise problematic. The idea is to use a “partners in innocence” response, combined with improbable conclusions if (one of) such hypothesis holds. Sorry if I gave the impression that you had argued that the arguments succeeded. I’m just arguing that they do not. If you take no stance on whether the arguments in question succeed, I’m trying… Read more »
Tony Y
Tony Y
At the beginning of your article you make a statement to the effect of ‘Imagine our brains are radically different’. That’s great when you are talking about imagining a fantasy world but such a condition can not exist! The genes instructing the formation of out neural circuits are some of the most conserved and any alteration/mutation will likely result in disaster due the incredible sensitivity of the developing nervous system. It seems far more likely that intuition is gleaned from experience (i.e. normal is dependent on the observer) and translated into specific neural pathways (synapses). I release this is a… Read more »
Angra Mainyu
I find myself wondering how we would know that our assessments are correct. I don’t often find myself wondering that, but I can if I choose to. However, it seems to me that one can raise that matter for any assessments whatsoever, not just color or moral assessments, but assessments about mathematics, philosophy, physics, astronomy, geology, chemistry, biology, and so on. I can say that we can check that they’re correct by our own lights, but of course, in doing so, we’re using our own intuitions and making probabilistic assessments (or similar ones). There is nothing else we can do.… Read more »