In his essay on epistemic operators, Dretske examines the limitations on an epistemic operator’s ability to penetrate to consequences of some proposition. From Dretske’s perspective, the basic idea of any operator is that when attached to a statement, an operator may apply itself–or penetrate–to additional statements which exist by consequence or association to the original statement. However, while he broadly defines a sentential operator as such, he also acknowledges that not all operators penetrate to every necessary consequence of a proposition. Consequently, Dretske creates a spectrum of operators, and their place on this spectrum often depends on their degree of penetration. Setting aside the whole set of epistemic concerns and arguments that deal with truth and what it means to say that something is true, fully penetrating operators, like “it is true that…”, occupy one side of the spectrum because they do penetrate to every necessary consequence of some proposition. If it is true that P and P entails Q, then it must also be true that Q. On the other side of this spectrum lies nonpenetrating operators, such as “it is strange that…” These operators are often used to apply some kind of subjective opinion or emotion to a proposition, and While it is strange that P and P might entail Q, it still might not be strange that Q. As a result, Dretske very much considers these subjective operators as nonpenetrating. What is perhaps most interesting about Dretske’s argument are his discussions on knowledge and where epistemic operators lie on this spectrum. In opposition to many philosophers who view epistemic operators as fully penetrating, Dretske argues that epistemic operators are actually only semi-penetrating due to their inability to penetrate presuppositions and contrast consequences. However, although the overall argument that Dretske makes in his essay is certainly compelling, certain assumptions and oversights call to attention not only important weaknesses in his essay but also logical contradictions to his own argument.
Before examining Dretske’s argument for all epistemic operators actually only being semi-penetrating, it is necessary to first clarify the specific conditions of his argument. Perhaps most importantly in arguments regarding epistemic operators, one must specify whether the individual who utilizes the operator knows or is aware of the consequential relation between two propositions. In other words, when analyzing the extent to which epistemic operators penetrate, the individual must know that P entails Q. In the case that the individual does not know that P entails Q, then an individual’s operation on P would not penetrate to Q for the obvious reason that the individual would not know of Q in the first place. As Dretske writes, “Were we all ideally astute logicians, were we all fully apprised of all the necessary consequences… of every proposition, perhaps then the epistemic operators would turn into fully penetrating operators.” Because most people are not “astute logicians,” limitations on knowledge result in limitations on epistemic operators because it would be impossible for an operator to penetrate to something that is unknown to the individual. However, there needs to be a crucial distinction between this sort of external limitation which depends on an individual’s wealth of knowledge and the internal limitations of epistemic operators, themselves, that prevent them from being fully penetrating. Because Dretske seeks to address the issues with epistemic operators, themselves, his examines the ability of epistemic operators to penetrate to all known consequences of a proposition.
Challenging the common assumption that epistemic operators–especially to know that–penetrate to all known consequences of a proposition, Dretske draws attention to two crucial reasons for which epistemic operators cannot be fully penetrating. First, Dretske argues that most propositions depend on a set of presumed conditions or presuppositions. While one can make statements using epistemic operators without explicitly stating every accompanying assumptions, epistemic operators do not penetrate to these presuppositions. In other words, if a proposition P is that A is B, one might have reason to believe that P. However, one might not have reason to believe that it is truly A which is B. In stating one might have reason to believe that A is B, there often exists a presupposition of what A is, and consequently, the epistemic operator “reason to believe that” does not legitimately penetrate to this presupposition. To provide an example of his argument, Dretske proposes the following:
Suppose you have a reason to believe that the church is empty. Must you have reason to believe that it is a church?
According to Dretske, one might reason to believe that the church is empty because perhaps you just made a thorough inspection of it without finding anyone. However, this inspection does not necessarily provide any reason to believe that it is even a church. As a result, the presupposition in this case would be that the empty building is a church, and one does not have any legitimate reason to believe in this presumed condition.
Although he provides many similar examples that demonstrate his claims, Dretske’s argument regarding presuppositions has major issues in that it not only fails to consider the role of more logical epistemic systems of knowledge. According to Dretske, by stating that one has reason to believe that a church is empty, one falsely applies an epistemic operator to the presupposition that the empty building is indeed a church. However, by only discussing assumptions and direct sensory (visual) experiences as reasons to believe, Dretske overlooks the utility of other epistemic systems, such as memory or inference, as a reason for belief. Perhaps, you have reason to believe that the empty building is a church because you remember attending services there every week. Or, maybe you have read a description of the church and its location, and from this information, you deduce that this must be the described church. In these cases, one would have as much reason to believe that the building is a church as the statement that the church is empty. Consequently, the epistemic operator, “reason to believe that,” would penetrate both the proposition that the building is a church and the proposition that the church is empty.
In addition to these larger, more general epistemic concerns, his argument on presuppositions also contains a smaller, logical contradiction that ultimately undermines the very conclusion that he attempts to make. In his example of the empty church, Dretske concludes that the church is empty because you just made a thorough inspection of it without finding anyone. However, the word, “empty,” implies something stronger than simply a lack of any person. Emptiness asserts that there is literally nothing in the church. Here lies Dretske’s contradiction. By emptiness, Dretske implied a state of lacking people. Though, one can easily imagine a situation in which this church lacks human presence but is full of other objects, such as chairs or paintings. Even if this church had just one small object in it, one could not legitimately claim that the church is empty. While criticizing the proposition–the building is a church–as a presupposition, Dretske himself makes a presupposition about what it means to be empty, thus contradicting his own argument.
Despite these issues with his argument on presuppositions, the second part of Dretske’s essay examines contrast consequences and how they relate to broader arguments about skepticism. Dretske writes:
Suppose we assert that x is A. Consider some predicate, ‘B’, which is incompatible with A, such that nothing can be both A and B. It then follows from the fact that x is A that x is not B.
The statements above establish the logical sequence which supports contrast consequences. The more complicated part of this sequence arises when the predicate B is joined with another predicate Q. Normal assumptions condition us to believe that because x is not B, x also cannot be B+Q. Therefore, we go about our lives not considering the possibility that the addition of another predicate Q can make B appear as A. Dretske argues that not only should people entertain the possibility of x being B+Q, but we must also recognize this possibility of x being B+Q just as much as the possibility of x being A. This argument is particularly significant if considered in discussions on skepticism. The skeptic argues that we do not know anything about the external world outside of our minds because we do not know (or have any reason not to believe) that our reality might be a false illusion. Although Dretske agrees with the skeptics in that we must acknowledge that we do not know these skeptical alternatives to be false, he also asserts that we must also recognize that we do not know if our reality is false. Contrast consequences, such as these, are not penetrated by epistemic operators because the B+Q predicate entertains all possible alternatives. We cannot say we know that x is B+Q just as much as we cannot say we do not know that x is B+Q.
In this way, explanatory contexts place statements in a network of possible alternatives. However, as we have evaluated, these alternatives may be infinite, and if an infinite number of alternatives exist, then the question becomes: how do we explain or give our reasons to believe anything? Dretske responds to this question by arguing that explanations exist by comparison to relevant alternatives. In other words, we define what it is that is being explained by defining what it is not. If you wanted to assert that x can only be A, then you might also assert that x cannot be B or B+C or Z or any other “relevant alternative.” For example, when explaining why she chose to eat eggs in the morning, she might justify herself by saying that she did not eat fruit because the fruit had mold on it or that she did not try the peanut butter muffin because she is allergic. Each of these alternatives inform why she chose to eat eggs, and as such, Dretske would consider them “relevant.” As a result, epistemic operators only penetrate to contrast consequences that form part of the proposition “matrix of relevant alternatives.” The problem with this claim then arises when we consider how would we distinguish a relevant alternative from the countless irrelevant alternatives.
While Dretske’s argument on presuppositions and contrast consequences has some serious logical and clarification issues, his essay on epistemic operators ultimately succeeds in support the broad notion that epistemic operators ought to be distinguished from fully penetrating and nonpenetrating operators. In particular, his argument which views knowledge as a more absolute concept presents a relevant and interesting challenge to skepticism by acknowledging that we cannot accept nor deny skepticism or reality until we are able to rule out all doubt.