Plantinga on Dentologism and Internalism

As mentioned in a previous post, I’m going to look at whether epistemic deontologism entails epistemic internalism. If having a justified belief is a matter of having fulfilled one’s epistemic duties, does it follow that the grounds of justification for the belief must be accessible upon reflection?

In Warrant: The Current Debate Alvin Plantinga answers the question above in the affirmative. Deontologism implies internalism. He does this by considering classical deontologism according to Descartes and Locke. The first internalist Motif (M) Plantinga derives from Descartes and Locke is:

(M1) Epistemic justification (that is, subjective epistemic justification, being such that I am not blameworthy) is entirely up to me and within my power. (p. 19)

(M1) is supported by the idea that whether a person has a justified belief is within the person’s control. Even if a person is a victim of a Cartesian demon, the person can still do her best with regard to her epistemic duties. This makes the person blameless regarding what she believes. Not being blameworthy is tied to the subject’s perspective. The idea of subjective epistemic justification is supported by two principles from moral theory:

(a) You are properly blamed for failing to do something A if and only if it is your duty to do A (and fail to do it). (p. 15)

You cannot be justly blamed for not doing something that it was not your duty to do. In addition, being a target of the reactive attitudes of guilt and blame hinges on what your mental states were toward what’s required or permitted by moral duty.

(b) If a person nonculpably believes that doing A is morally required or permitted, then she is not guilty (not to be blamed) for doing A; and if she nonculpably believes that refraining from doing A is morally required or permitted, then she is not guilty (not to be blamed) for refraining from doing A. (p. 16)


If I believe that it is my duty, all things considered, to do A, then I am guilty, culpable, morally blameworthy if I do not do A. (p. 16)

So nonculpable belief or knowledge regarding what duty requires excuses one from blame when one does something wrong. You have to know that it was your duty or that you were violating your duty in order to be blameworthy for doing so. It helps to note that this idea goes against the idea from legal theory that ignorance of the law is no excuse for violating the law. Plantinga claims legal duty differs from moral duty in this regard. He uses the example of stealing to indicate that you are only blameworthy for violating a duty if you knowingly violate that duty:

Assume, just for the purposes of argument, that the ground of the obligation not to steal is the divine command “Thou shalt not steal.” I could hardly be blamed for stealing if I (nonculpably) didn’t know that stealing is wrong or didn’t know, of a given act of stealing I am performing, that it is wrong, or didn’t know, of a given act of taking something, that it is indeed an act of stealing. You are guilty, or to blame or properly subject to censure only if, as we say, you knowingly flout your duty. Ignorance may be no excuse in the law; but nonculpable ignorance is an excusing condition in morality. (pp. 16-17)

Principles (M1), (a), and (b) show that justification is a matter of not being blameworthy and not being blameworthy is a matter of what’s within one’s ken, what’s within one’s control. Plantinga lands this point on the Ought Implies Can (OIC) principle, as he indicates:

All that is required is that I do my subjective duty, act in such a way that I am blameless. All I have to do is my duty; and, given that ought implies can, I am guaranteed to do that. So justification is entirely within my power; whether or not my beliefs are justified is up to me, within my control. My system of beliefs may be wildly skewed and laughably far from the truth; I may be a brain in a vat or a victim of a malicious Cartesian demon; but whether my beliefs have justification is still up to me. (p. 19)

Next Plantinga puts on the table another motif from classical deontologism and three corollaries of that motif. The second internalist principle ties together subjective and objective duty. Objective duty holds that success, not a mere attempt, is what counts regarding doing one’s duty. Objective duty requires succeeding in matching assent or belief to the support that belief receives from one’s total evidence.

(M2) For a large, important, and basic class of objective epistemic duties, objective and subjective duty coincide; what you objectively ought to do matches that which is such that if you don’t do it, you are guilty and blameworthy. (pp. 19-20)

(M2) has three corollaries. According to the first Corollary (C):

(C1) In a large and important set of cases, a properly functioning human being can simple see (cannot make a nonculpable mistake about) what objective epistemic duty requires. (pp. 20-21)

Descartes and Locke think I do not directly determine whether a belief is justified. Instead I indirectly determine whether its justified by figuring out whether, for Locke, “it is probable with respect to what I know”, or, for Descartes, “whether it is clear and distinct for me”. This way of figuring out whether a belief is justified is the ratio cognoscendi of justification. Whether a belief has the ratio cognoscendi of justification is something that a cognitively well-functioning person can readily determine.

(C2) In a large and important class of cases a properly functioning human being can simply see (cannot make a nonculpable mistake about) whether the proposition has the property by means of which she tells whether a proposition is justified for her. (p. 21)

In addition, the means by which you determine whether a belief has the property of justification (i.e., the ratio cognoscendi) coincides with what makes the belief justified (i.e., the ratio essendi, the cause or ground of justification). A properly functioning epistemic agent is inerrant when it comes to figuring out whether a belief has the property that makes it justified. This leads to the last corollary.

(C3) In a large, important and basic class of epistemic cases a properly functioning human being can simply see (cannot make a nonculpable mistake about) whether a proposition has the property that confers justification upon it for her. (p. 22)

Plantinga proceeds to connect the classical deontological view of justification with contemporary theories of epistemic justification. Regarding justification as something involving duty fulfillment and evidential support finds its way into many contemporary views. The result being that deontologism entails internalism. It entails that the grounds that make a belief justified, and that the belief is justified, are things that are accessible upon reflection or otherwise internal to the subject.

Does epistemic deontologism entail epistemic internalism?

Over a few blog posts I want to consider answers to this question. Alvin Plantinga answers the question in the affirmative. Anthony Brueckner responds to Plantinga’s argument. According to Brueckner, deontologism doesn’t preclude the possibility of an externalist approach to epistemic justification. Michael Bergmann provides further support for the possibility of combining deontologism with externalism. And Anthony Booth responds to Brueckner and Bergmann. I’ll start out with shorts posts getting each author’s position on the table. Then I’ll end with a post where I put in my two cents. I’m looking forward to it!

In Memory of Anthony Brueckner

I’m deeply saddened by the passing of my friend and mentor, Anthony Brueckner. He inspired me to do philosophy. He inspired me to explore my interests. He came along side me in that exploration, and he guided me to a clearer and more streamlined expression of my own thoughts and ideas. I’m going to miss his anecdotes, relating a philosophical point to something from pop culture–often a quote from a movie or a song. I’m going to miss hearing him coming down the hall of the department, continually clearing his throat, knowing that Tony B. was near. I’m going to miss seeing him wearing that worn brown leather jacket, carrying that worn leather briefcase. But, most of all, I’m going to miss talking to him about philosophy. If I have a philosophical hero it is Tony Brueckner. He has provided myself, and so many others, with a model of intellectual humility, intellectual honesty, generosity with one’s time, and rigorous attention to details. As he says in his monograph (2010: 5), “As one often finds in philosophy, the devil is in the details.” I’m going to miss you, Tony B.

The Principle of Indifference and Epistemic Reasons

The Principle of Indifference (PoI) is plausibly defined as follows:

  • (Pol): Each member of a set of propositions should be assigned the same probability (of truth) in the absence of any reason to assign them different probabilities. (Castell 1998: 387)

(PoI) is a principled way to assign probabilities in situations of epistemic ignorance. When you have no reason to assign probabilities to a set of propositions in one way versus another way (PoI) instructs you to assign a uniform distribution of probabilities across the propositions in the partition. Despite being a principled way to assign probabilities, given ignorance, there are problems with (PoI).

A well-known problem with (PoI) is Bertrand’s paradox. The upshot of Bertrand’s paradox is that unless (PoI) is somehow restricted it results in inconsistent assignments of probabilities to the same event. Equally valid ways of carving up the outcome space (i.e., the propositions in the partition) result in (PoI) assigning different uniform distributions to the same event. How the outcome space is described changes the probability value (PoI) recommends. (PoI) is description-dependent and inconsistent as a result. A lesser-known problem with (PoI) involves reliance on the notion of a ‘reason’ in the definition of PoI (i.e., “in the absence of any reason…”). This is the issue that I want to explore.

As Paul Castell (1998: 388) points out, you can generate different iterations of (PoI) based on the strength that you assign to the notion of an epistemic reason. How strong does a consideration in favor of believing that p have to be in order to count as a reason to believe that p?

Epistemic reasons can vary in strength. I might believe that Sheriff Chance is corrupt because I saw her take a bribe from an ex-convict named Stumpy, or I might believe that Sheriff Chance is corrupt because I suspect that she is corrupt. Assuming my suspicion is merely a suspicion, and not based on solid evidence, the former reason to believe that the Sheriff is corrupt is stronger than the latter reason.

In general, adopting a weaker understanding of ‘reason’ generates a stronger (i.e., more stringent) version of (PoI). Such a version of (PoI) is more stringent because it is a more demanding principle. To qualify as being in a state of epistemic ignorance requires not having any reason to assign different probabilities to the propositions. If, for instance, a mere suspicion qualifies as a ‘reason’, then you cannot possess any suspicion that one proposition is more likely than the others. If you have such a suspicion, then you have a reason to assign them different probabilities and (PoI) does not apply. This puts a high bar on what it takes for (PoI) to apply to a situation of uncertainty. The inverse also holds: a stronger understanding of ‘reason’ generates a weaker (i.e., less stringent) version of (PoI). If, for instance, only knowledge qualifies as a ‘reason’, then you cannot possess any knowledge that one proposition is more likely than the others. Because knowledge is a stronger epistemic concept than mere suspicion it will be easier to qualify as being in a state of epistemic ignorance (i.e., possessing no reasons). This places a low bar on what it takes for (PoI) to apply to a situation of uncertainty. These generalizations are as follows:

  • High Bar: A weak interpretation of ‘reason’ yields a strong interpretation of (PoI);
  • Low Bar: A strong interpretation of ‘reason’ yields a weak interpretation of (PoI).

Before trying to set the bounds of interpretations of (PoI) by finding iterations of (PoI) that satisfy High Bar and Low Bar it would be good to get a grip on how these considerations create problems for (PoI). One aspect of the worry is that (PoI) generates probability distributions (i.e., quantities) contingent upon the interpretation of a qualitative notion (i.e., a reason). If you think traditional epistemology should inform formal epistemology, then this may not be much of a worry. However, if you think things should work in the opposite direction or not at all (i.e., formal epistemology should inform traditional epistemology or they should be regarded as domains that don’t meaningfully interact), then this may be regarded as a worry. However, the deeper worry is akin to the problem Bertrand’s paradox causes (PoI).

What I call the ‘Many Interpretations’ problem for (PoI) results in inconsistent assignments of probabilities to the same event. The problem is not generated based on a redescription of the propositions in the partition. Rather, the problem is generated based on a reinterpretation of (PoI). For instance, this can occur when a Low Bar interpretation of (PoI) is applicable to an epistemic situation, so it recommends a uniform distribution of probabilities, but a High Bar interpretation of (PoI) is not applicable to the same epistemic situation, and a non-uniform distribution of probabilities results. How (PoI) is interpreted determines whether or not it is applicable to one and the same epistemic situation, which results in inconsistent application of the principle, and inconsistent assignment of probability values. Is the Many Interpretations problem something that Bayesians need to worry about?

At first glance it appears that Subjective Bayesians aren’t impacted by the Many Interpretations problem. Subjective Bayesians do not require a ‘reason’ to assign probabilities to propositions. Such Bayesians regard (PoI) as unnecessary, no matter how it is interpreted. As Castell (1998) explains about this Bayesian position:

The thought is that where you do not feel in a position to make a (warranted) probabilistic judgement given the available evidence, the proper thing to do is simply to abstain from judgement. According to this view, it is unreasonable to wheel in a principle that provides probabilities where you judge none to be warranted: there is no role for (Pol) within Bayesianism. (p. 388)

Castell argues that Bayesians must (and in fact do) rely on (PoI) in assigning probabilities. In the interest of space I will not rehearse the details of his argument. However, there is a good case to be made that Bayesians rely, even if only implicitly, on (PoI), and in certain situations Bayesians must rely on (PoI) because no frequency data is available in the facts of the case or in the background information. So, I think that, despite professions otherwise, this objection to (PoI) is pressing for Bayesians as well.

Let’s explore a few iterations of (PoI). Castell (1998) articulates two iterations of (PoI) in an attempt to find a High Bar version of (PoI). The first iteration of (PoI) involves judgment (J):

  • (PoI-J): Each member of a set of propositions should be assigned the same probability in the absence of a subjective judgement to the contrary. (p. 388 n.4)

Castell recognizes that (PoI-J) is problematic. We don’t make probabilistic judgments about many things. This is often because we have not thought about the matter. Do we really assign a uniform distribution to things that we have never thought about? Castell thinks that we need to introspect on such things. This generates the second iteration of (PoI), which involves introspection and judgment (IJ):

  • (PoI-IJ): Each member of a set of propositions should be assigned the same probability if due consideration (introspection) yields no subjective judgement to the contrary. (p. 388 n.4)

Though I wouldn’t put (PoI-IJ) at the upper limit of High Bar, (PoI-IJ) is a viable option for a High Bar version of (PoI). This is because the notion of a ‘reason’ is relatively weak. As Castell says about (PoI-IJ), “where an agent feels unable to make any judgements (however weakly based on evidence), it directs him to adopt the uniform distribution” (p. 388 n.4). (PoI-IJ) is a more stringent principle because it requires you to not have any subjective judgment “however weakly based on evidence” in order to assign a uniform distribution of probabilities. By contrast, a viable option for a Low Bar version of (PoI) involves knowledge (K):

  • (PoI-K): Each member of a set of propositions should be assigned the same probability if due consideration (introspection) yields no knowledge to the contrary.

(PoI-K) has a strong interpretation of ‘reason’ and generates a weak version of (PoI). It requires you to not have any knowledge that one (or more) of the propositions should be assigned a different probability. Such knowledge is harder to come by, so (PoI-K) is easier to satisfy. There is a Low Bar regarding the applicability of (PoI-K) to a situation of uncertainty.

Along the High Bar/Low Bar spectrum there is a range of interpretations of (PoI). Such interpretations include having no intuition, no reasonable doubt, and no belief to the contrary.

The Many Interpretations problem calls for a restriction of (PoI) to prevent inconsistent assignments of probabilities to the same event. Is a Low Bar or a High Bar interpretation of (PoI) more likely to be correct? If it’s possible to argue that one interpretation is the correct interpretation, then other interpretations can be ruled out. This delimits the permissiveness of (PoI) and prevents multiple interpretations from generating different probabilities. However, such a move greatly reduces the scope and power of (PoI). It will not be possible to apply (PoI) to many situations of epistemic uncertainty, situations that are not ruled out under a permissive understanding of (PoI).


Castell, Paul. 1998. A Consistent Restriction of the Principle of Indifference. The British Journal for the Philosophy of Science 49: 387-95.