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Brabbelus
Essay · 4 July 2026 · 18 min

In Defence of Intuitions as Evidence

Introduction

[1] It is wrong to sacrifice five people for the life of one person.

[2] If P then Q, P, Thus Q

[3] For all natural numbers x, y and z, if x = y and y = z, then x = z

When considering the three propositions listed above, the propositions seem either to be true or false. No rational thought has consciously taken place, no considerations for arguments for and against occurred, when considered the propositions above simply seem to be true or false. This seeming to be true/false is a mental state that is called a philosophical intuition. In modern philosophical methodology intuitions have been given high status when it comes to serving as evidence for philosophical claims and theories. Much of modern philosophy can be said to be partaking in the “method of cases”. Cases are thought experiments, scenarios that philosophers create which have been constructed to elicit a certain intuitive judgement about a philosophical concept. This intuitive judgement will then be used as evidence to argue for or against a philosophical claim or theory. The method of cases argues that a philosophical theory of a certain concept, C, is only a good theory of C if it can predict and properly explain the intuitive judgements that we have about C.1

The locus classicus of such a method is the short paper, Is Justified True Belief Knowledge? by Edmund Gettier.2 In that paper Gettier sets out to disprove what he terms as the Justified True Belief theory of knowledge. The JTB theory is a theory of when a person can be said to have knowledge of a proposition. The theory says that one has knowledge of a certain proposition when one has the belief that that proposition is the case, that one has a justified reason for their belief in that proposition, and that the proposition is true. If all those boxes are checked then we can say that a person has knowledge of that proposition. Gettier’s thought experiment goes as follows: suppose two men, Smith and Jones, are both applying for the same job. Jones has his interview first and passes Smith in the hallway where Jones accidentally drops his wallet and from his wallet ten coins spill unto the floor. Smith takes note of this as he walks towards the interview room where he overhears the interviewer speaking with another saying the following: “That Jones guy is terrific! He’ll surely get the job”. From these two propositions, Jones has ten coins in his pocket and Jones is going to get the job, Smith deduces the following proposition: [4] the person who is going to get the job has ten coins in his pocket. Of this proposition Smith has a justified true belief and thus according to the JTB theory of knowledge he knows that the person who is going to get the job has ten coins in his pocket.

But now imagine that unbeknownst to Smith the interviewer discovers that Jones has a criminal record invalidating him from the interviewing process, leaving Smith the only applicant left for the job. And even more coincidentally it turns out that in Smith’s pocket there are exactly ten coins, which again he is unaware of. While proposition [4] remains true, Smith still believes it and through the rules of logical deduction he is quite justified in that belief, can we say that Smith knows that the person who is going to get the job has ten coins in his pocket?

Much like the propositions considered at the start of this paper likely when considering the previous question there was an intuitive answer to this question. For Gettier, and for most philosophers, the philosophical intuition was that Smith did not know proposition [4]. According to the method of cases the JTB theory of knowledge is thus not an adequate theory of knowledge because it does not accurately predict and explain the intuitive judgements about when one has knowledge in the Gettier case.

The Method of Cases and more fundamentally the use of intuitions as justificatory evidence in philosophical argumentation has gained widespread support. In the modern era of philosophy thought experiments are being created and used as argumentative points more often than ever before. New philosophical movements, such as that of Experimental Philosophy, which focus explicitly on the study of intuitions have gained increasing popularity. Experimental philosophers conduct empirical tests to investigate numerous characteristics of intuitions, such as whether intuitions about philosophical cases vary across cultures, socioeconomic backgrounds, or personality types. Further research is done into exactly how an intuition relates to a philosophical concept through the presentation of a hypothesis about intuition which is empirically tested.3

But of course, not all philosophers agree that intuitions play the evidential role described by the method of cases and as in the explanation of the Gettier Case above. The most prominent of these “Intuition Deniers” is philosopher Herman Cappelen, who argues in his book Philosophy Without Intuitions4 that philosophers do not actually rely on intuitions in philosophical argumentation. Cappelen’s thesis presents an existential threat to movements such as experimental philosophy and the method of cases. It threatens a mass revision of our understanding of how philosophy is practiced in its modern form. Because of the effects that Cappelen could cause, in this paper I hope to answer the following question: Do intuitions serve as evidence in philosophical argumentation?

To do so I will first present what Cappelen calls the argument from philosophical practice. In this argument Cappelen analyzes several primary sources from philosophers which contain thought experiments and argues that in none of them an intuition is used as evidence. I will specifically apply Cappelen’s argument from philosophical practice to Gettier’s Is Justified True Belief Knowledge?. I believe Cappelen’s argument sets too strict a requirement of what counts as an intuition. Further I believe the requirements that Cappelen sets mischaracterize how an intuition serves as evidence in philosophical argumentation. I will present my arguments against Cappelen and attempt to define where Cappelen’s characterization of intuitions went wrong. Hopefully in doing so rescuing experimental philosophy and the method of cases from Cappelen’s onslaught and thereby defending the legitimacy of intuitions as evidence in philosophical practice.

The Argument from Philosophical Practice

In the argument from philosophical practice Cappelen defines an intuition as a judgement with the following features:

(F1) They have a special phenomenology

(F2) They are based on conceptual competence

(F3) They have a special epistemic status in that they justify but do not require justification (Cappelen refers to this as Rock)

Analyzing ten different articles, which feature arguments that supposedly rely on intuitions, Cappelen analyzes the argumentation and argues that any premise which is supposedly justified by an intuition does not have any of his features of an intuition and therefore must be something else. While (F1) and (F2) are features of intuitions which are heavily debated in the literature they are theoretical claims about the nature of an intuition, and are less important when specifically looking at how an intuitive judgment serves as justificatory evidence in an argument.5

(F3) is of our specific interest. Cappelen gives the following guide to the detection of (F3) in a philosophical argument: “If in a context C, evidence and arguments are given for p and those arguments evidence plays a significant argumentative role in C, that is evidence that p is not Rock (F3) relative to C”.6 Thus if we have a premise, p, take for example the premise we saw earlier in the Gettier case, Smith has a justified true belief of the proposition but he does not know the proposition, if Gettier anywhere in his paper (the context as Cappelen calls it), provides a justification, whether an argument, a testimony, an introspection, or perceptual justification then the third feature of an intuition is not present. And thus neither is an intuition present in the argumentation.

Let us look again at the Gettier case to see if (F3) the special justificatory status of the intuition is present. The underlying structure of the Gettier case is paradigmatic for the general structure of thought experiments, thus showing how Cappelen’s argument works on the Gettier case shows how it will work for all similar arguments.7

Gettier starts out with a general theory which he wishes to disprove, in Gettier’s case this is the JTB theory of knowledge which we can construe as, it is necessarily true that if someone, X, has a justified true belief of a proposition, P, then X knows P. Then a thought experiment is suggested in this case the scenario with Smith and Jones. We can take as our first premise of the Gettier case that it is possible for someone, X, to stand to a proposition, P, in the same way as Smith stands to the proposition that “whoever is going to get the job has ten coins in his pocket”.

The next step was claiming that in the Gettier case Smith did not have knowledge of the proposition “whoever is going to get the job has ten coins in his pocket” even though he did have a justified true belief of that proposition. We can sum this up as our second premise of the Gettier case: it is necessarily the case that if X stands to P as in the Gettier case then X has a justified true belief of P, but X does not know P.

At this point in Gettier’s argumentation we have two premises the first says that it is possible the Gettier case could occur. The second says that if the Gettier case were to happen then necessarily X would have a justified true belief of P, but X would not know P. The necessary consequence of a possible antecedent is possible therefore from our first two premises we can conclude it is possible for X to have a justified true belief of P, but not know P. This conclusion contradicts the general theory we started with proving that it is inadequate. This analysis comes from The Philosophy of Philosophy by Timothy Williamson where he also formalizes the argument using modal logic8:

K (x, p):       x knows that p.
JTB (x, p):     x has a justified true belief that p.
GC (x, p):      x stands to p as in the Gettier text.

(JTB) ◻∀x∀p (JTB (x, p) = K (x, p)).

(1) ⬦∃x∃pGC (x, p)
(2) ◻∀x∀p (GC (x, p) ⊃ (JTB (x, p) & ∼K (x, p)))
∴ (3) ⬦∃x∃p (JTB (x, p) & ∼K (x, p))

What this entire debate turns on is the justification for the second premise, how can we justify that Smith does not have knowledge even though he has a justified true belief of the proposition that “whoever is going to get the job has ten coins in his pocket”? In the explanation of the Gettier case in the introduction I claimed that our evidence for the second premise is an intuitive judgement, it seems to be true that that Smith does not know that “whoever is going to get the job has ten coins in his pocket”. In order for that to be in line with Cappelen’s features of an intuition, (F3) must be present if it is not then Cappelen claims that what we are using to justify the second premise is something other than an intuition. Thus looking through Gettier’s text we are looking for any explicit argumentation or any other sort of justification for why Smith has a justified true belief that P but that he does not know P.

After the claim that Smith does not know that the man who is going to get the job has ten coins in his pocket, premise 2, Gettier writes the following: “it is equally clear that Smith does not know that (e) is true; for (e) is true in virtue of the number of coins in Smith’s pocket, while Smith does not know how many coins are in Smith’s pocket, and bases his belief in (e) on a count of the coins in Jones’s pocket, whom he falsely believes to be the man who will get the job”.9 This is clearly an argumentative justification given as to justify premise 2 of the Gettier case! (F3) cannot be present and thus the justification for the Gettier case is contra to the popular understanding of the Gettier case not an intuitive judgement. At least according to Cappelen.

The Flaws of the Argument From Philosophical Practice

At first glance, Cappelen’s analysis appears successful. Gettier does provide explicit justification for premise 2 in the Gettier case, which according to Cappelen’s detection method means (F3) is absent and therefore no intuition is doing evidential work. Yet the argumentation also feels incredibly unintuitive. And for good reason as I believe Cappelen’s conclusion rests on two fundamental mistakes in Cappelen’s argumentation. Firstly (F3) is a strawman of the intuition literature, and even if (F3) were to be a proper characterization of how intuitions serve as evidence then Cappelen’s method for detecting (F3) does not prove that intuitions are not present.

The strawman accusation might seem sudden but it comes from an aspect of Cappelen’s book I have not yet explained. In Philosophy Without Intuitions10 Cappelen does not present a positive argument for why philosophy does not rely on intuitions. Instead he attempts to disprove arguments for the thesis that philosophy relies on intuitions. The argument from philosophical practice is the most extensive and important of these arguments in which Cappelen says that people believe philosophers rely on intuition because they use them as evidence in philosophical argumentation. In order to disprove this argument he sets up the three features of what an intuition is based on the literature surrounding intuition. According to Cappelen (F1) comes from the work of Pollock11, Plantinga12, and Bealer13. He does not give the explicit names for (F2) but I have found it in the writings of Devitt14 and Kornblith15.

The strawman problem arises with (F3), Cappelen claims16 that he has pulled the feature from the work of Weinberg17 with the following quotation:

In the extant practice of appeal to intuitions as philosophical evidence, one cites one’s application or withholding of a concept from a given case, usually a hypothetical one, in defense of (or in order to attack) a particular philosophical claim. Such citations thus are meant to carry argumentative, evidential weight, but one is not usually required to offer any further argumentation for the intuition itself. […] Although they are used to provide evidence, one does not, and need not, provide further evidence for them18.

This seems to clearly be the (F3) that Cappelen uses. But as Weinberg points out in his own response19 to Cappelen this is not at all the point Weinberg was making, as in the following line he says this, “However, they are not generally taken to be incorrigible or indubitable…. We may choose not to endorse an intuition if the balance of evidence speaks against it, or if one comes to think that the intuition was not formed in a sufficiently truth-conducive way”.

On Weinberg’s characterization of an intuition the status of an intuitive judgement as justifier is not that it needs no justification but that it only provides prima facie justification. (F3) the key feature of Cappelen’s argument is thus not pulled from any work of an intuition theorist but is a strawman of the position of Weinberg. Since Cappelen has mischaracterized what intuition theorists actually claim about the epistemic status of intuitions, his attempt to disprove their position by showing that philosophical arguments don’t meet (F3) attacks a position nobody actually holds.

The other fatal problem with Cappelen’s argumentation is the way he attempts to identify (F3). Namely according to Cappelen, if an author argues for p in context C that is evidence that p is not (F3) in context C. This principle is simply false. Namely an argument used as justification for a proposition, lets take as a concrete example premise 2 of the Gettier case again, does not mean that there is no intuition used as evidence as well.20 Consider premise 2 of the Gettier case again, if we were to remove those two sentences that Gettier attached to the thought experiment, which Cappelen believes is the sole justification for the second premise, we would still be able to justify the second premise because we have the intuitive judgement that premise 2 is the case. As Chalmers points out if anything we would expect Gettier not only to have the intuition as his sole justification of premise 2, but having an argument to justify premise 2 as well puts him in a more robust position.21 The argument does not replace or remove the intuition, nor was it the case that the intuition was never there, it means simply that the position of the thought experiment becomes stronger.

Conclusion

In conclusion Cappelen’s argument fails on two levels. His characterization of intuition misrepresents what intuition theorists actually claim, and even if that problem did not exist his claim that if an argument is used as a justifier in a text an intuition cannot be used to justify the same point is simply incorrect. The presence of an argument does not show that no intuition is present it is simply good philosophical practice to provide more evidence for one’s points. His analysis of the Gettier case fails to show that intuitions are not used to justify the Gettier case as he holds a mischaracterized definition of an intuition. And even if we grant his definition, it still fails to show that an intuition is not used.

To answer the question posed at the start of this paper: Yes, philosophers do rely on philosophical intuitions as evidence in philosophical argumentation. Cappelen’s challenge fails to undermine this practice.

Bibliography

Bealer, George. “Intuition and the Autonomy of Philosophy.” In Rethinking Intuition: The Psychology of Intuition and Its Role in Philosophical Inquiry, edited by Michael Raymond DePaul and William M. Ramsey. Rowman & Littlefield Publishers, 1998.

Cappelen, Herman. Philosophy Without Intuitions. Oxford University Press UK, 2012.

Chalmers, David J. “Intuitions in Philosophy: A Minimal Defense.” Philosophical Studies 171, no. 3 (2014): 535–44. https://doi.org/10.1007/s11098-014-0288-x.

Devitt, Michael. “Intuitions in Linguistics.” British Journal for the Philosophy of Science 57, no. 3 (2006): 481–513. https://doi.org/10.1093/bjps/axl017.

Gettier, Edmund L. “Is Justified True Belief Knowledge?” Analysis 23, no. 6 (1963): 121–23. https://doi.org/10.1093/analys/23.6.121.

Knobe, Joshua, and Shaun Nichols. “Experimental Philosophy.” In The Stanford Encyclopedia of Philosophy, Winter 2017, edited by Edward N. Zalta. Metaphysics Research Lab, Stanford University, 2017. https://plato.stanford.edu/archives/win2017/entries/experimental-philosophy/.

Kornblith, Hilary. The Role of Intuition in Philosophical Inquiry: An Account with No Unnatural Ingredients. Edited by Hilary Kornblith. 1998.

Plantinga, Alvin. Warrant and Proper Function. Oxford University Press, 1993.

Pollock, John L. Knowledge and Justification. Edited by John Pollock. Princeton University Press, 1974.

Pust, Joel. “Intuition.” In The Stanford Encyclopedia of Philosophy, Fall 2024, edited by Edward N. Zalta and Uri Nodelman. Metaphysics Research Lab, Stanford University, 2024. https://plato.stanford.edu/archives/fall2024/entries/intuition/.

Weinberg, Jonathan M. “Cappelen Between Rock and a Hard Place.” Philosophical Studies 171, no. 3 (2014): 545–53. https://doi.org/10.1007/s11098-014-0286-z.

Weinberg, Jonathan M. “How to Challenge Intuitions Empirically Without Risking Skepticism.” Midwest Studies in Philosophy 31, no. 1 (2007): 318–43. https://doi.org/10.1111/j.1475-4975.2007.00157.x.

Williamson, Timothy. The Philosophy of Philosophy. Wiley-Blackwell, 2008.

Footnotes

  1. Joel Pust, “Intuition,” in The Stanford Encyclopedia of Philosophy, Fall 2024, ed. Edward N. Zalta and Uri Nodelman (Metaphysics Research Lab, Stanford University, 2024), https://plato.stanford.edu/archives/fall2024/entries/intuition/. ↩

  2. Edmund L. Gettier, “Is Justified True Belief Knowledge?,” Analysis 23, no. 6 (1963): 121–23, https://doi.org/10.1093/analys/23.6.121. ↩

  3. Joshua Knobe and Shaun Nichols, “Experimental Philosophy,” in The Stanford Encyclopedia of Philosophy, Winter 2017, ed. Edward N. Zalta (Metaphysics Research Lab, Stanford University, 2017), https://plato.stanford.edu/archives/win2017/entries/experimental-philosophy/. ↩

  4. Herman Cappelen, Philosophy Without Intuitions (Oxford University Press UK, 2012). ↩

  5. David J. Chalmers, “Intuitions in Philosophy: A Minimal Defense,” Philosophical Studies 171, no. 3 (2014): 535–44, https://doi.org/10.1007/s11098-014-0288-x. ↩

  6. Herman Cappelen, Philosophy Without Intuitions (Oxford University Press UK, 2012). ↩

  7. Timothy Williamson, The Philosophy of Philosophy (Wiley-Blackwell, 2008). ↩

  8. Timothy Williamson, The Philosophy of Philosophy (Wiley-Blackwell, 2008). ↩

  9. Edmund L. Gettier, “Is Justified True Belief Knowledge?,” Analysis 23, no. 6 (1963): 121–23, https://doi.org/10.1093/analys/23.6.121. ↩

  10. Herman Cappelen, Philosophy Without Intuitions (Oxford University Press UK, 2012). ↩

  11. John L. Pollock, Knowledge and Justification, ed. John Pollock (Princeton University Press, 1974). ↩

  12. Alvin Plantinga, Warrant and Proper Function (Oxford University Press, 1993). ↩

  13. George Bealer, “Intuition and the Autonomy of Philosophy,” in Rethinking Intuition: The Psychology of Intuition and Its Role in Philosophical Inquiry, ed. Michael Raymond DePaul and William M. Ramsey (Rowman & Littlefield Publishers, 1998). ↩

  14. Michael Devitt, “Intuitions in Linguistics,” British Journal for the Philosophy of Science 57, no. 3 (2006): 481–513, https://doi.org/10.1093/bjps/axl017. ↩

  15. Hilary Kornblith, The Role of Intuition in Philosophical Inquiry: An Account with No Unnatural Ingredients, ed. Hilary Kornblith (1998), 129–41. ↩

  16. Herman Cappelen, Philosophy Without Intuitions (Oxford University Press UK, 2012). ↩

  17. Jonathan M. Weinberg, “How to Challenge Intuitions Empirically Without Risking Skepticism,” Midwest Studies in Philosophy 31, no. 1 (2007): 318–43, https://doi.org/10.1111/j.1475-4975.2007.00157.x. ↩

  18. Jonathan M. Weinberg, “How to Challenge Intuitions Empirically Without Risking Skepticism,” Midwest Studies in Philosophy 31, no. 1 (2007): 318–43, https://doi.org/10.1111/j.1475-4975.2007.00157.x. ↩

  19. Jonathan M. Weinberg, “Cappelen Between Rock and a Hard Place,” Philosophical Studies 171, no. 3 (2014): 545–53, https://doi.org/10.1007/s11098-014-0286-z. ↩

  20. David J. Chalmers, “Intuitions in Philosophy: A Minimal Defense,” Philosophical Studies 171, no. 3 (2014): 535–44, https://doi.org/10.1007/s11098-014-0288-x. ↩

  21. David J. Chalmers, “Intuitions in Philosophy: A Minimal Defense,” Philosophical Studies 171, no. 3 (2014): 535–44, https://doi.org/10.1007/s11098-014-0288-x. ↩

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