In his paper, “The Content-Force Distinction”, Peter Hanks claims that three prominent semantic accounts of interrogatives—those of Hamblin (1973), Karttunen (1997), and Groenendijk and Stokhof (1982, 1997)—are all inadequate because they fail to preserve the univocality of “knows that” (e.g. Jones knows that Smith is tall) and “knows whether” (e.g., Jones knows whether Smith is tall). I will not examine the three accounts of interrogatives that Hanks impugns here. Nor will I attempt to assess the various replies to Hanks’ argument that may be offered on behalf of the three approaches in order to show that they can, in fact, preserve the univocality of “knows” across cases of “knows that” and “knows whether”. Instead, I will examine Hanks’ argument directly, and challenge the assumption that the term “knows” is univocal in the way Hanks suggests.
Hanks begins by noting that the term “knows” is genuinely ambiguous when used in its acquaintance sense (e.g., “Jones knows Wilson”) and in its propositional sense (e.g., “Jones knows that Smith is tall”). This is what explains the infelicity of the following sentence:
(1) Jones knows that Smith is tall and Wilson.
In short, it is ambiguity of “knows” in its acquaintance and propositional senses that explains the infelicity of (1). Hanks draws the preliminary conclusion that one cannot form a conjunction with a genuinely ambiguous use of “knows” (in the manner illustrated in (1)) without infelicity. So goes the first stage of Hanks argument.
The second stage of Hanks’ argument consists in his contention that the difference between “knows that” and “knows whether” is best conceived of as the difference between a knowledge claim that modifies indicative content and a knowledge claim that modifies interrogative content, respectively. In support of this conclusion, Hanks invites us to consider two statements:
(2) Jones knows that Smith is tall.(3) Jones knows whether Smith is tall.
It is clear that (2) and (3) have different contents. Suppose that Jones knows that Smith is not tall. In that case, (2) would be false, while (3) would be true. But how are we to make sense of the difference between (2) and (3). It is tempting to view (3) as a disjunction of two knowledge claims, along the lines of (4):
(4) Either Jones knows that Smith is tall or he knows that Smith is not tall.
On the present suggestion, “knows whether” is elliptical for a disjunction of a pair of competing “knows that” claims.
However, Hanks maintains that the above analysis of “knows whether” is unsatisfactory. This is because the commitment to compositionality requires that we see expressions like “whether Smith is tall” as making the same semantic contribution to different sentences in which it occurs. But this requirement cannot be satisfied if we conceive of (3) along the lines of (4). For example, consider (5):
(5) Jones asked whether Smith is tall.
If we assume that “knows whether” statements are an elliptical treatment of a disjunction, then (given the commitment to compositionality) we would have to interpret (5) along the lines of (6):
(6) Either Jones asks that Smith is tall or Jones asks that Smith is not tall.
But (6) is clearly infelicitous. Hence, interpreting “knows whether” as a disjunction comes at the cost of compositionality.
According to Hanks, our best chance of making sense of (3) in a way that satisfies the compositionality requirement is to hold that the embedded expression “whether smith is tall” is an instance of interrogative content. How we understand interrogative content will of course depend on our theory of interrogatives, which is what is under dispute in Hanks’ paper. But the basic idea is this: the expression “Jones knows whether Smith is tall” is best interpreted along the lines of “Jones knows the answer to: is Smith tall?” This is the conclusion of the second stage of Hanks argument.
In the third, and final, stage of his argument, Hanks observes that the following claim is felicitous:
(7) Jones knows that Smith is tall and whether Wilson is married.
According to Hanks, this suggests that “knows” is not ambiguous across “knows that” and “knows whether”.
Given that “know that” is a knowledge claim with embedded indicative content, and “know whether” is a knowledge claim with embedded interrogative content, it follows that “knows” is not ambiguous across indicative and interrogative content. Hence, Hanks concludes that those accounts of interrogative content that fail to preserve the univocality of “knows” across indicative and interrogative contents are mistaken.
Here is a recap of all three stages of Hanks’ argument and his conclusion:
Stage 1: One cannot form a conjunction with a genuinely ambiguous use of “knows” without infelicity.
Stage 2: “knows that” and “knows whether” correspond with knowledge claims with embedded indicative content and interrogative content, respectively.
Stage 3: One can form a conjunction with “knows that” and “knows whether” without infelicity.
Conclusion: Knowledge claims with embedded indicative content and embedded interrogative content do not involve a genuinely ambiguous use of “knows”.
I believe that the first stage of Hanks argument is unsound. Consider the following sentence:
(8) Jones knows how to play the piano and that the concert is being held downtown.
(8) is no less felicitous than (7). However, (8) features an ambiguous use of “knows”. The first conjunct is an instance of “know how” while the second conjunct is an instance of “know that”. Or, for another example, consider (9):
(9) Jones knows how to play the piano and whether the concert is being held downtown.
(9) is also perfectly felicitous. But it too involves an ambiguous use of “knows”. The first conjunct is an instance of “know how” and the second conjunct is an instance of “know whether”.
(8) and (9) illustrate that is possible to have a conjunction that features the ambiguous use of “knows” without infelicity. Hence, we cannot conclude from the fact that (7) is felicitous that it involves a univocal sense of “knows”. The upshot is that it is unclear that three prominent theories of interrogative content Hanks mentions have the burden of preserving the univocality of “knows” across “knows that” and “knows how” since the claim that there is such univocality remains unestablished.