3.3 Modal accounts of genericity
3.3.3 Drewery (1998)
Drewery (1998) discusses generic statements in conjunction with other lawlike state-ments from a philosophical point of view.38 She distinguishes three types of general-izations: (i) “true laws”, (ii) “ceteris paribus laws”, and (iii) accidental generalizations.
True laws and ceteris paribus laws, in contrast to accidental generalizations, are non-accidental, lawlike regularities. Ceteris paribus laws also differ from true laws and accidental generalizations in their tolerance for exceptions. Specifically, the excep-tional individuals and circumstances are assumed to be filtered by a ceteris paribus clause.
Conceptually, Drewery argues that true laws are special cases ofceteris paribus laws, i.e. laws for which no exceptional individuals or circumstances exist. This is motivated by the observation that true laws and ceteris paribus laws—in contrast to accidental generalizations—can be expressed with generic sentences.
Drewery stresses the importance of a detailed analysis of the nature of exceptions to determine the truth-conditions for generic sentences. In fact, the task of determining the set of appropriate exceptions for a given generic sentence is seen as the central issue on which all other interpretational aspects of generic sentences are based. This assumption is motivated by the following considerations: Exceptional individuals and circumstances do not have arbitrary properties. Or rather, the properties that are responsible for making individuals or circumstances exceptional with respect to a given generic statement are neither random, nor independent from the generalization that is expressed. Exceptions underlie other, specific regularities that are in conflict with the regularity expressed by the generic statement, and that override it. In most cases, the exact regularity that is seen as the reason for why a given individual counts as an exception cannot be determined. However, the specific, conflicting properties are assumed to belong to the same greater body of rules, e.g. moral principles, legal codes,
the set of “ideal” individuals forF. Formally, the two operators differ with respect to their properties regarding reasoning with generic sentences. For details cf.Eckardt(2000).
38Drewery(1998) exclusively discusses bare plural generic sentences. She notes, though, that indef-inite singular generic sentences, and generic sentences that involve kind predication are linguistically more restricted.
physical laws of nature, or genetic laws. This greater body of rules exists independently, and is part of world knowledge.39
Drewery’s (1998) focus on the nature of exceptions is connected to an observation first made inCarlson(1977): The properties that constitute an exception depend on the properties in the restrictorand the properties in the scope of the generic operator. That is, no single set of exceptional Fs can be determined for different generic statements about individuals with property F. Any account that proposes such a “static” set of exceptions makes undesirable predictions. Consider the true generic statement in(55), and assume that a three legged dog Fido exists in the world of evaluation that lost its leg in an accident.
(55) Dogs have four legs.
With respect to(55), Fido is a legitimate exception, i.e. Fido is in the set of exceptional dogs.40 But, even though Fido is an exceptional dog with respect to having four legs, Fido is not an exception to(56).
(56) Dogs are mammals.
If the set of exceptional dogs were determined independently of the property denoted by the predicates have four legs and be a mammal, Fido would have to be both a member of the set of exceptional dogs and a member of its complement.
From these considerations, Drewery infers that the set of exceptional individuals for a given generic sentence depends on the two properties that are related by the generic sentence, and that the set is determined in a principled way relative to a greater body of law.
The core idea of Drewery’s formal proposal is to model the considerations and intu-itions about legitimate exceptions, and to take this result as the basis from which all other aspects of the interpretation of generic sentences are determined.
Drewery calls the set of individuals that count as legitimate exceptions to a given generic statement its exception class. Its complement is the set of non-exceptional individuals. Drewery models the set of non-exceptional individuals with the help of a primitive function NF,G, which depends on the restrictor F and the scope G of the generic operator.41 The extension of NF,G in an arbitrary world w is the set of all (actual and possible) non-exceptionalFs with respect to G, see (57).42
39For an account of generic sentences which also stresses the role of the speaker’s beliefs/knowledge seeter Meulen(1986,2012).
40Incidentally, Fido and Paul are friends.
41The propertyNF,G is intended to perform the role of theceteris paribus clause.
42Drewery(1998) does not work in a system with explicit world variables, and assumes world-relative individual domains. Consequently, the extension of an expression likeNF,G(x) is always determined relative to the world in whichxexists.
(57) NF,G(x)⇔x is a non-exceptionalF with respect to being G (Drewery 1998:91)
The following example illustrates how NF,G is determined for the sentence Peacocks have a brightly coloured tail.
(58) Npeacock, has-a-brightly-coloured-tail = actual or possible peacocks without the exception class, i.e. without the females, juveniles, those whose tails have been amputated and so on.
(Drewery 1998:92)
In other words, the set of non-exceptional Fs with respect to being G contains those individuals that are not filtered out by another rule.
In Drewery’s account, the modal accessibility relation involved in generic sentences is derived from the set of non-exceptional individuals. The set NF,G is used to determine an equivalence relation ∼F,G on the set of possible worldsW, which creates a partition on W. The resulting equivalence classes are such that all worlds in a class share the same set of non-exceptional F-individuals with respect to beingG.43
(59) w1 ∼F,Gw2 iff the extension ofNF,G inw1 = the extension of NF,G in w2 (Drewery 1998:91)
The relevantly similar worlds that are accessible from the world of evaluation are all and only the worlds that are members of the equivalence class of the world of evaluation.
From the way in which w1 ∼F,G w2 is determined, it follows that the accessible worlds agree (i) on the individuals that are to be considered non-exceptional with respect to a specific, world-dependent body of law, and (ii) on the content of the relevant body of law used to determine NF,G.
In sum, Drewery proposes that generic sentences of the form Fs are G have the following truth-conditional content.
(60) In all possible worlds in which the same Fs are non-exceptional with respect to being G(as in the world of evaluation), all non-exceptional Fs with respect to being Gare G.
(Drewery 1998:91, elaboration in parentheses added for clarification)
Notably, Drewery assumes that every individual only exists in one single possible world. To make her system independent from this assumption, and compatible with a shared domain of individuals (as is usually assumed in the literature on modality),
43An equivalence relation on a domainAis a reflexive, symmetric, and transitive relation. A set of elements related to each other by an equivalence relation is a subset ofA, and is called an equivalence class induced by the relation. The set of equivalence classes constitutes a partition on A, i.e. the classes are pairwise disjoint and their union isA.
I give a translation of her account into a system with explicit world variables and a constant individual domain.
The first step is to let NF,G assign a set of pairs of individuals and worlds to a given world w.44
(61) A pair hx, w0iis inNF,G(w) iffxis a non-exceptionalF with respect toGfrom the point of view of the world w, but with respect to its properties in w0. The similarity relation ∼F,G is also adapted to fit the new version of NF,G: The relation ∼F,G partitions the set of worlds depending on whether the worlds pick out the same set of individual-world-pairs based on the body of rules under consideration.
This is defined in(62).
(62) w1 ∼F,Gw2 iff ∀hx, wi[NF,G(w1)(hx, wi)↔NF,G(w2)(hx, wi)]
The right side in (62) is equivalent to NF,G(w1) = NF,G(w2). Therefore, in all worlds that are accessible from the world of evaluationw, the set of non-exceptional Fs with respect to beingG is constant, and can be simplified to NF,G(w).
In combination, the translation of Drewery’s account for the meaning of generic statements of the form Fs are G into a system with explicit world variables results in the truth-conditional content proposed in(63).
(63) ∀w0[w∼F,G w0 → ∀x[F(x)(w0) & NF,G(w)(hx, w0i)→G(x)(w0)]]
Drewery’s account captures both desiderata for modal accounts of Gen listed at the end of Section3.3.2: (i) The accessibility relation is defined based on the functionNF,G
that models the set of non-exceptional F-individuals with respect to being G, and (ii) the function NF,G depends on the property denoted by the material in the restrictor and the material in the scope ofGen.
Hence, the problems identified for the account in Krifka et al. (1995) in the pre-vious section do not apply to Drewery’s account. Drewery discusses her solution for the problem regarding restrictive modification of the subject property in detail. Her account captures that the introduction of restrictive modifiers changes the set of ac-cessible worlds: The truth of a generic sentence depends first and foremost on the function NF,G, which, in turn, depends on the properties F and G. Therefore, if the subject property F is restricted by a property K, it cannot be ensured that the set NF,G(w) stands in any kind of well-defined relation to the set NF&K,G(w) (for an ar-bitrary world w). In principle, NF,G(w) and NF&K,G(w) cannot be identical, and do
44This definition is compatible with both world-dependent domains of individuals and a single domain of world-independent individuals. Since non-exceptionality is determined with respect to facts in specific worlds,∀x∀w, w0, w00[¬(hx, wi ∈NF,G(w00)→ hx, w0i ∈NF,G(w00)] holds. That is, an individualx may be inNF,G(w00) with respect to its properties in w, but may be an exceptional F with respect to beingGrelative to its properties inw0.
not have to stand in a subset relation; the two sets of non-exceptional individuals may even be disjoint. Drewery illustrates this last possibility with the following example (adapted from Drewery 1998:108–110 to the revised formalism).
(64) Students take exams.
Assume that the generic statement about students in (64) is true inw with respect to the body of law governing educational institutions in w. Assume also that there is a special school, the University of Carlops, where students are not evaluated by taking exams, but via a continuous assessment system. Thus, it is also true in w that
(65) Students at Carlops University do not take exams.
This means that students at the University of Carlops count as exceptional students with respect to taking exams. Hence, Nstudent,take-exams(w) will not contain any pairhx, wi where x is a student at Carlops in w. However, NCarlops-student,take-exams(w)45 will contain only individuals which are students at Carlops University. Therefore, there is no hx, wi such that Nstudent,take-exams(w)(hx, wi) andNCarlops-student,take-exams(w)(hx, wi).
This observation can be generalized to any type of modifying material. Formally, all properties that are interpreted in the restrictor of the generic operator have this effect.
This includes not only adjectival or prepositional modifiers of the subject noun phrase, but also relative clauses andif/when-clauses restrictingGen. AsDrewery(1998) points out, scenarios like the one above are a problem for any account of restricted generic sentences in which restrictions are simply intersective modifiers on the domain of indi-viduals, e.g. the modal proposal of Krifka et al. (1995).
Even though Drewery’s proposal captures both crucial desiderata for a modal account of Gen, some aspects of her account are, to my mind, problematic. One issue of Drewery’s proposal concerns her view on the scope of the data that can be captured by her account. She argues that the value of NF,G is context dependent since (i) the truth of generic sentences can change over time, and (ii) generic sentences without an overt modal can sometimes be interpreted as if it contained an overt modal element.
Regarding the first point, I argue that a change in content of NF,G over time is not context dependence as observed e.g. for modals, anaphora, and other context dependent material. Compare the examples in (66).
(66) a. Scenario: Peter sneezes ten times.
Just now, Peter had to sneeze ten times.
45Drewery (1998:95) argues that, in general, NF,G =NF,¬G if the body of rules is held constant.
For example in the actual world, penguins are exceptional birds with respect to flying. However, they are also exceptional birds with respect to not flying, because Penguins do not fly is true, although Birds do not fly is judged false. That is, to evaluate the generic statementBirds do not fly the same set of birds is considered as for evaluatingBirds fly.
b. Scenario: Properties of dogs are discussed.
#Just now, dogs had four legs.
Note that the value of NF,G does not change from one moment to the next, which is implied by the phrase just now. Even if at the moment referred to by just now the truth of a generic sentence holds, pointing out one specific instance is pragmatically odd. In contrast, obligations expressed by modals may change more freely.
Drewery’s second point above is based on the observation that generic sentences without overt modal elements sometimes express the same regularity as a corresponding generic sentence with an overt modal element. Compare(67-a) and (67-b).
(67) a. Countries with common borders share their resources.
(Drewery 1998:93)
b. Countries with common borders must share their resources.
Example(67-a) has two readings. In its first reading, it is understood as a description or report of a regularity regarding the conduct of countries with common borders. This regularity is motivated by legal or moral considerations, and may be based on a series of observations for countries of this kind in the world of evaluation. In the second reading,(67-a)expresses a legal or moral necessity for countries with common borders.
This reading(67-a) shares with(67-b). Drewery argues that which of the two possible interpretations is understood depends on “the kind of modality implied in the context”
(Drewery 1998:93), and is also not an instance of context-dependent variation as found with e.g. modals. While one and the same modal may be used with different flavors in the same utterance, see(68), no variance of this sort is observable for generic sentences.
(68) Peter canepistemic only be at his neighbor’s place right now because he told me that he candeontic watch Germany’s Next Topmodel there.
It can be shown that generic sentences that express ideal rules of conduct, i.e.(67-a)in its second interpretation, cannot be captured in Drewery’s system. Since both readings of(67-a)express a regularity based on the legal/moral body of law in force at the world
of evaluation, both readings are modelled by assuming thatNcountries-with-common-borders,share-their-resources
is determined with respect to this body of law. For the second reading, Drewery sug-gests that(67-a) expresses the same statement as (67-b). Hence, both sentences have the same truth-conditions. In particular, both sentences are interpreted relative to the same non-exceptional individuals. This means that the overt modal in(67-b)does not contribute any additional meaning to the shared truth-conditions.
Undesirable predictions arise because the definition of the accessibility relation in-duced by NF,G cannot capture generalizations about ideals: the accessibility relation
∼F,G is by definition realistic, independently of the body of law used to determine NF,G.46
(69) w1 ∼F,Gw2 iff NF,G(w1) =NF,G(w2)
(70) ∀w0[w∼F,G w0 → ∀x[F(x)(w0) & NF,G(w0)(hx, w0i)→G(x)(w0)]]
Consequently, Drewery’s account predicts that no true counterexamples for generic sentences may exist in the world of evaluation. If even a single counterexample were to exist in the world of evaluation, the sentence would immediately come out as false.47 This means that generalizations about ideals cannot be captured as soon as the gener-alization is violated in the world of evaluation. Unfortunately, in a situation in which a generic sentence is intended to be taken as a rule of conduct typically some non-conforming non-exceptional individuals exist—their existence motivates the use of the generic sentence in the first place. Crucially, the speaker is not unsure whether the non-conforming individuals are in fact exceptional. If the non-conforming individual were exceptional, the speaker’s utterance of the rule of conduct would not be motivated any more. Consider example (71).
Scenario: A finds out that B, a student, is still living at his parents’ place.
(71) A to B: Studenten student
wohnen live
doch prt
nicht not
mehr still
zu at
Hause!
home A to B: ‘Students don’t still live at their parents’ place!’
In (71), A intends to convey is that B should not live at his parents’ place any longer.
He neither questions B’s being a student, nor his non-exceptionality regarding the rule.
If B were not a student or an exception to the rule, A’s utterance would not apply to B in the first place, and B would not feel criticized. Consequently, the rule expressed in (71) can be valid, even though the non-exceptional individual B violates it in the world of evaluation.
Since Drewery assumes that sentences like(71)have a realistic accessibility relation, she cannot capture this example. In fact, two results follow from the discussion above:
(i) Drewery’s proposal can only capture generalizations that are not violated in the world of evaluation, and (ii) generic sentences with overt modals cannot be modelled as proposed by Drewery. That is, the presence of an overt modal has an effect on the truth-conditions of a generic sentence.
46The set of accessible worlds contains those worldsw0 that are in the equivalence class of the world of evaluationwwith respect toNF,G. Hence,wwill always be in the set of accessible worlds.
47In fact, no individual that does not conform to the rule or norm expressed by a generic sentence may exist in any accessible world.
Dahl’s (1975) class of “descriptive lawlike statements” are, however, unproblematic for Drewery’s account.48
I leave the problem of the second interpretation of sentences like (67-a) and (71) for further research since a detailed analysis of these examples necessarily involves an investigation of their primary discourse function to enforce the rule, norm, or ideal expressed by the sentence. This investigation is beyond the scope of this thesis.