Introduction to Pragmatics

Transcription

1 Introduction to Pragmatics Summer 2016 Tuesdays 2321.HS 3H INSTRUCTOR Todor Koev (Todor.Koev@uni-duesseldorf.de)

2 Presupposition projection Presupposition is a prevalent type of inference in language. We have looked at various properties of presupposition, incl. presupposition projection. Presupposition projection: the ability of presuppositions to survive when the sentence is negated, modalized, conditionalized, or questioned. Example: Both sentences in (1) imply (2). (1) a. Ben found his glasses. b. Ben didn t find his glasses. (2) Ben has/wears glasses.

3 The projection problem The projection problem: How do the presuppositions of a sentence depend on the presuppositions of its parts? The cumulative hypothesis: The sentence as a whole inherits all of the presuppositions of its parts. Example: (3) A presupposes p B presupposes q A and B presupposes p and q A or B presupposes p and q... This is the idea behind the Family of Sentences Test.

4 Three-valued logic We fleshed out the cumulative hypothesis in a three-valued logic. There are three truth values: 1 (true) 0 (false) # ( undefined / infelicitous ) Three-valued logic incorporates classical logic: o If truth values assigned to subformulas are classical (1 or 0), then the entire formula is classical (1 or 0). o If, however, one or more parts of a formula are undefined (#), then the entire formula is undefined (#). Undefinedness projects from smaller parts to the entire sentence. A single instance of presupposition failure renders the entire sentence infelicitous. This analysis predicts that presuppositions never disappear.

5 Problems Presuppositions typically project past operators (negation, etc.). However: Presuppositions are sometimes cancelable. They do not always project! Presuppositions can be blocked in a variety of syntactic environments, e.g. conditionals, conjunctions, disjunctions. Conditional antecedents (=if-clauses) can sometimes block presuppositions triggered in the main sentence (the consequent). (4) Jessica s brother must be tall. Jessica has a brother. (5) If Jessica has a brother, her brother must be tall. >/> Jessica has a brother.

6 Problems cont d Initial conjuncts can block presuppositions triggered by by second conjunct. (6) presupposes that Mike has a car. (7) entails but does not presuppose that Mike has a car, as seen from (8). (6) Mike s car is expensive. Mike has a car. (7) Mike s has a car and his car is expensive. Mike has a car. >/> Mike has a car. (8) It s possible that [Mike has a car and his car is expensive]. >/> Mike has a car.

7 Problems cont d Finally, disjuncts too can block presuppositions. (9) The bathroom is in a funny place. There is a bathroom. (10) This house has no bathroom or the bathroom/it is in a funny place. >/> There is a bathroom. Presuppositions do not always project. This argues against the cumulative hypothesis and is bad news for the three-valued account of projection. The million dollar question: Is presupposition cancelation random or is there a pattern to it?

8 Empirical generalizations Presuppositions are not canceled by negation. (11) Ben didn t find his glasses. Ben has/wears glasses. Presuppositions are canceled when entailed by a previous conjunct. (12) It s possible that [Mike has a car and his car is expensive]. >/> Mike has a car. Presuppositions are canceled when entailed by a previous if-clause. (13) If Jessica has a brother, her brother must be tall. >/> Jessica has a brother. Presuppositions are canceled when negated in a previous disjunct. (14) This house has no bathroom or the bathroom is in a funny place. >/> There is a bathroom.

9 A discourse-based account We discuss the local context account of presupposition projection. It preserves the idea that presupposition failure results in infelicity. However, it also pays attention to the way information is processed in discourse. Main idea: Presuppositions should be entailed by the context (the shared body of information) with respect to which a clause (not the entire sentence!) is interpreted. Static view: Sentence meaning is truth conditions. Dynamic view: Sentence meaning is context change (the way a sentence updates the information shared among interlocuters). The account is termed in set theory.

10 Possible world semantics Static view: Semantics is about truth conditions. Each sentence is true or false. John is smart 1 or John is smart 0 o is the interpretation function. o S is the meaning of sentence S. Static possible world view: A sentence is true or false with respect to a possible world (w 1, w 2, ). w John is smart 1 w 1, John is smart 2 0, etc. Equivalently: The meaning of a sentence is the set of all possible worlds in which the sentence is true. John is smart { w John is smart in w }

11 What is a possible world? A possible world is any conceivable way the world could be. You can think of a possible world as a situation or a state of affairs or what is the case or. Formally: A possible world is a formal object that determines the truth value of each sentence. So: Sentences are not true or false simpliciter. They are true or false in a given possible world. If is the actual world (=the world as we know it), then Snow is white is true in

12 From statics to dynamics Utterances update our information about the world. The meaning of a sentence is the effect it has on the (linguistic) context. Def (context): The set of possible worlds which are compatible with everything we know. c { w w is compatible with everything we know} Alternatively: A context is the set of possible worlds which are live candidates to represent the actual world Sentences affect c in different ways depending on their content and their structure. c +A means we update context c with sentence A OR sentence A is uttered in context c

13 Dynamic semantics Def (entailment): Context c entails atomic sentence q iff In words: c entails q iff q is true in all worlds in c. Atomic sentences: (15) In words: c p if c entails q c p q # otherwise Complex sentences: c q. p can be felicitously uttered in c only if c entails its presupposition q. (16) c not- A c ( c A ) (negation) (17) c A and B ( c A) B (conjunction) (18) c A or B ( c A) ( c not- A) B (disjunction) (19) c if A then B ( c not- A) ( c A) B (conditional)

14 Comments This dynamic semantics achieves two things at the same time: I. It gets the truth conditions right. II. It accounts for the pattern of presupposition projection observed above, namely: i. Presuppositions project through negation (and other operators). ii. Presuppositions can be blocked in conjunctions, disjunctions, and conditional sentences.

15 Getting the truth conditions Assume that p and q are atomic sentences with no presupposition triggers in them. So p and q trigger no presuppositions. c not- p c ( c p ) (16) c ( c p ) (15) c p (set theory) o Updating c with not-p removes all worlds in c in which p is true. c p and q ( c p) q (17) ( c p ) q (15) o Updating c with p and q intersects c with p and with q. Practice: What do c p or q and c if p then q amount to?

16 Example: Using the semantics Let the conjunctive sentence It s sunny and I m going out be uttered in the context c, where c ={w 1, w 2, w 3 }, It s sunny ={w 1, w 2 }, I m going out ={w 1, w 3 } Compute the meaning of the sentence in c. c + It s sunny and I m going out = (c + It s sunny) + I m going out (17) = (c It s sunny ) I m going out (15), applied twice = ({w 1, w 2, w 3 } {w 1, w 2 }) {w 1, w 3 } (given) = {w 1, w 2 } {w 1, w 3 } (intersection) = {w 1 } (intersection) Q: Why is this the intuitively correct result?

17 Getting presupposition projection Assume that p and q are atomic sentences and that q presupposes p. c not- q c ( c q ) (16) p p o According to (15), c q p is only defined if c, the starting or global context, already entails p. o That is, presuppositions project through negation. c p and q ( c p) q (17) p p o According to (15), ( c p) q p is only defined is c + p entails p. o This is necessarily true! So asserting p in the first conjunct blocks the presupposition p of the second conjunct. Practice: What is the predicted projection pattern for c not- p or q p and c if p then q p?

18 Example 2: Conditionals Generalization from above: Presuppositions are canceled when entailed by a previous if-clause. (20) Jessica s brother is tall. >> Jessica has a brother. (21) If Jessica has a brother, her brother is tall. >/> Jessica has a brother. Model: c = {w 1, w 2, w 3, w 4 } q c p = Jessica has a brother = {w 1, w 2 } p w 1 w 2 q = her brother is tall = {w 1, w 3 } w 3 w 4 Logical form for (21): if p then q p

19 Example 2: Tasks Tasks: i. Truth conditions If (21) is uttered in the context c, what do you expect the context c + (21) to be (ignoring any presuppositions)? Compute the truth conditions for c + if p then q in the above model. ii. Presupposition projection Derive from the dynamic semantics the intuition that the presupposition p of q is canceled / does not project / does not impose any restrictions on the global context c.

20 Example 2: Intuitions Truth table for (21): w w w w p q We can view the rows in the truth table as possible worlds. The input context is c = {w 1, w 2, w 3, w 4 }. The only world that falsifies the sentence is w 2, so we expect the output context to be c + if p then q = {w 1, w 3, w 4 }. Let s find out!

21 Example 2: Truth conditions c if p then q ( c not- p) ( c p) q (19) ( c ( c p)) ( c p) q (16) c p c p (15) { w1, w2, w3, w4} { w1, w 2} (given) { w, w } ( ) 1 2 ( c { w, w }) { w, w } q (above) c { w1, w 2} { w1, w2, w3, w4} { w1, w2} { w3, w 4} (given, ) { w, w } q { w, w } q { w, w } { w, w } { w } (15, given, ) { w3, w 4} { w1} (above) { w, w, w } ( ) 1 3 4

22 Example 2: Presupposition proj c if p then q p ( c not- p) ( c p) q p (19) ( c ( c p)) ( c p) q p (16) ( c ( c p)) (( c p) q ), if c + p entails p (15) Tackling the presupposition p of q requires that the context c + p entails p. Since this will always hold no matter what p might stand for the presupposition p is guaranteed to be always true. We correctly predict that the presupposition of (21) that Jessica has a brother does not project / is canceled / does not impose any restrictions on the global context c!

23 Global vs. local context Two notions of a context in semantics/pragmatics: o Linguistic context: The information shared among speech participants, because it was uttered or can be safely assumed as background knowledge. (We covered this notion today.) o Non-linguistic/Utterance context: the speaker, the hearer, the time, the place of the utterance, etc. (Yet to be discussed.) Global vs. local linguistic context: o Global context: The initial context against which the entire sentence is interpreted. o Local context: The initial context + any information introduced by a previous part of the same sentence. o For sentence-initial clauses: global context = local context.

24 Quick check Imagine that a derivation delivered the following, where p and q are atomic sentences: c ( p and q) ( c p) q o What is the global context for p? o What is the local context for p? o What is the global context for q? o What is the local context for q? o Is the global context the same for all parts of the sentence? o Is the local context the same for all parts of the sentence?

25 Summary Dynamic semantics makes a shift in perspective: from static truth conditions to dynamic updates of the context. It captures the truth conditions of complex sentences and explains why presuppositions are sometimes canceled. If a presupposition is independent of the sentence meaning, the presupposition needs to be entailed by the global/initial context. o We get the intuition of that this presupposition projects. If, however, some initial part of the sentence has already added to the context the presupposition of a later part of the sentence, the presupposition will necessarily be entailed by the local context. o We feel that the presupposition is blocked / not required to hold in the initial context. Presuppositions need to be entailed by the local/immediate context, not necessarily by the global context in which the entire sentence is uttered!

26 For next time Please read: Conventional implicature