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Appeal to Intuition: A Naturalistic Fallacy?

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Philosophers, and perhaps others, will be familiar with the naturalistic fallacy. It is committed when someone tries to say that something can be good or right in virtue of its being natural. In this post, I wish to suggest that if the naturalistic fallacy is indeed a fallacy, then philosophers might commit it when they appeal to the intuitiveness, conceivability, or the “seeming” truth (Huemer 2001) of a proposition.

To begin, I ask you to imagine that your brain and my brain are radically different from one another. If this were the case, then it would be unsurprising if our intuitions, (mental) conceptions, and judgments about what ‘seems’ true (or possible) would vary. Indeed, evidence suggests that even minor differences (or developments) between brains can have these effects (Adelstein et al, Amodio et al, Costa et al, De Drue et al, DeYoung et al, Harris et al, and Kanai et al).

This implies that our appeals to intuition (etc.) might be contingent upon brains being a certain way. In other words, our intuitions could be a ‘natural’ consequence of neural properties. If they are, then when philosophers appeal to them in order to convince their audience that a proposition is better or worse (more or less true, or more or less probable, etc.) they commit the naturalistic fallacy. After all, getting buy-in from these appeals could depend on an audiences’ intuitions (etc)—and certain natural properties—being a certain way.

So when philosophers get their audience to buy-in to a particular proposition by appealing to intuitiveness (etc.), it might not be in virtue of the proposition being true (or probable or good, etc.). Rather, it could be that the audience is similar enough to the philosopher, neurally speaking, to buy it. For example, most people have an intuition that it is wrong to torture infants. This common intuition could be the result of people having certain neural features in common.

But what about when peoples’ intuitions differ? Even in these cases, there is some reason to think that the difference is related to neural differences (Amodio et al 2007). So maybe neural differences are also to blame when appeals to intuitiveness (etc.) do not work. This raises an a crucial question: what should we think when a select few members of a large group have different intuitions than their neighbors? Should we call these minority intuitions ‘non-natural’?

It might depend upon what we mean by non-natural. If we mean mainstream or majority, then sure: their intuitions are non-natural. However, if we mean not-at-all-the-consequence-of-natural-properties, then I think we have ventured into indefensible territory. Defending such a claim with thorough evidence would be tough, especially since there exists a wealth of evidence that differences in intuition correlate differentially with certain properties of the nervous system. So intuitions can be held by a minority and still be a natural result of natural properties.

You might be thinking, “Ok. I see how there can be nuanced differences between philosophers’ intuitions, but what about really abnormal intuitions?”

Psychopaths and sociopaths might be good examples of people with really abnormal intuitions. What should we think about their intuitions? Should we call them non-natural? Again, we could allow this insofar as they are not mainstream. But we would be unwise to claim that psychopaths’ intuitions are super-natural. Given the limited evidence on neural correlates of intuitive judgments  (e.g. Glenn et al 2009, and see also Kahane et al 2012 and Koenigs et all 2011 for the other perspective), we should probably suspect that there is some story to be told about differential neural properties in psychopaths’ really abnormal intuitions.

But if psychopaths’ and non-psychopaths’ intuitions are as natural as non-psychopaths’ intuitions, then how do we adjudicate between these intuitions? Clearly both sets of intuitions cannot be correct; otherwise contradictions would emerge—this is one example of how interpreting goodness or correctness in virtue of naturalness gets us into trouble. When people imply that a psychopath’s intuitions are somehow wrong, they cannot make this judgment in terms of the natural properties behind the psychopaths intuitions. They must show that psychopathic intuitions are bad in virtue of something else (e.g. bad consequences, being false, etc.). If this can be shown—and this is crucial—then appeals to intuitions might be kosher after all…or some of them might be.

At this point one might be desiring more or better evidence of our intuitions being dependent on natural properties—I would be sympathetic to that desire. If you find yourself with this desire, let yourself temporarily, for the sake of thinking about something deeply interesting, grant that our intuitions are a natural phenomenon. Having granted this, you would encounter a problem: lots of philosophers openly and unashamedly appeal to the intuitiveness (etc.) of propositions which seems to imply that lots of philosophers are openly and unashamedly committing the naturalistic fallacy. So if philosophical methodology is to have a good reputation, then philosophers will need to either (a) stop appealing to the intuitiveness of propositions altogether or (b) show how the intuitions to which they appeal are reliable (in virtue of something other than their being natural, or naturally intuitive).

Personally, I think deciding what to do will not be easy. When it comes to using intuitions in decision-making, there are cases where our intuitions serve us well and there are cases where our intuitions lead us astray. So we must try to show what it is that makes some intuitions reliable and other intuitions unreliable if we are to be responsible with our appeals to intuitions.


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Nick Byrd

Nick is a cognitive scientist studying reasoning, wellbeing, and willpower. When he is not teaching, in the lab, writing, exercising, or relaxing, he is blogging at www.byrdnick.com/blog