Questions, Answers and Presuppositions Marie Duží & Martina Číhalová

Logic Café2 Dialogue between a computer and a general C: Missiles are coming. G: Over sea or over land? C: Yes. G: Yes what? C: Yes, sir.

Logic Café3 Queries with Presuppositions  Many important features of questions are based on their presuppositions. Everybody who is at least partially acquainted with the methods applied in social sciences has heard of the importance to consider the presuppositions of a question in questionnaires. Did you stop smoking? Q: Did you stop smoking? presupposes that you did smoke; Did all the trucks deliver their cargo? Q: Did all the trucks deliver their cargo? A: Yes. Hence all the cargo has been delivered Q: Hence all the cargo has been delivered? Yes. … Presupposition: there were some trucks delivering cargo; hence there is some cargo delivered.

Logic Café4 Multi-agent system (MAS)  Taking into account presuppositions of questions is in particular important in case of building a multi- agent system  Autonomous, (less or more) intelligent agents  No central dispatcher communicate by messaging  Agents are active, communicate by messaging, make decisions, infer consequences, follow their goals  messages: Inform, Order, Query, Unrecognised, …  The content of messages is analysed in TIL  In order that the system is not prone to inconsistencies, the agents should communicate in an intelligent way

Logic Café5 Multi-agent system (MAS)  Imagine communication not respecting presuppositions: Did all the trucks deliver their cargo Q: Did all the trucks deliver their cargo? The system based on FOL: x Truck(x)  Delivered_Cargo(x) Yes (because there are no trucks delivering) Hence, all the cargo has been delivered Q: Hence, all the cargo has been delivered? Yes (because no cargo has been delivered) OK, I will inform the sellers that the goods have arrived ???

Logic Café6 QUESTIONS AND ANSWERS empirical interrogative sentence  The question posed by an empirical interrogative sentence S is the -intension denoted by S. Hence, the question is an -intension of type   whose -value in the actual world w and time t the questioner would like to know. -value of Q  a direct answer to the question Q is a construction of an -value of Q in a given world-time pair of evaluation. -value of Q is a  a complete answer to the question Q is a construction of the proposition that the -value of Q is a  The type of a Yes/No question is a proposition; hence, a direct answer provides a truth-value.

7 Wh-questions  Who is... ? Who is the Mayor of Ostrava? wt [ 0 Mayor_of wt 0 Ostrava]     Types: Mayor_of/()  ; Ostrava/.  Which...? Which mobile agents are going to Prague? wt x [[[ 0 Mobile 0 Agent] wt x]  [ 0 Going_to wt x 0 Prague]]  ()   Types: Mobile/(()  ()  ): a property modifier; Agent/()  ; Going_to/()  ; Prague/.  Open issue: do wh-questions come attached with a presupposition? (In our opinion, yes, but not the above ones.)

Logic Café8 Exclusive-or questions:..., or... ?  “Is the parking lot P 1 vacant or occupied?”  The answer will not be Yes/No (not inclusive but exclusive or); rather, the answer conveys one of the properties vacant, occupied wt [ 0 I p [[p wt 0 P 1 ]  [[p = 0 Vacant]  [p = 0 Occupied]]]] Types: p/* 1  v ()  ; I/(()  (()  )): the ()  - singularizer; P 1 /; Vacant, Occupied/() .

Logic Café9 Presupposition of a question  Standard definition: presupposition is entailed by each complete answer to the question  What is presupposed must be true under each answer to a question. In other words, a presupposition is entailed by each complete answer to the question. Works well in case of positive answers, but negative answers are problematic Complete answer is a propositional construction.  “Who is the Mayor of Ostrava?”  Direct answer: ‘Mr. Kajnar’.  Complete answer: “The Mayor of Ostrava is Mr. Kajnar”.

Logic Café10 Presupposition vs. mere entailment (i) P is a presupposition of S: (S |= P) and (non-S |= P) Corollary: If non-P then neither S nor non-S is true; S has no truth-value. (ii) S merely entails (but does not presuppose) P: (S |= P) and neither (non-S |= P) nor (non-S |= non-P)

Logic Café11 Presupposition vs. mere entailment survival under negation We follow Frege and Strawson in treating survival under negation as the most important test for presupposition. narrow-scope negation wide-scope negation But a negative answer to a question is often ambiguous. The ambiguity consists in not distinguishing between two kinds of negative answers, to wit the answers applying a narrow-scope negation and wide-scope negation. While the former preserves presupposition, the latter seems to be presupposition denying.

Logic Café12 Two kinds of negation Q: Did you stop beating your wife? A: No Q: Hence you still beat her? It is not true that I stopped … (wide-scope) A: No (?) I did not stop … (narrow scope)

Logic Café13 Two kinds of negation Who is the Mayor of Ostrava Q: Who is the Mayor of Ostrava? A: Tomáš Machura (or Petr Kajnar, or, …)  the Mayor exists A: Nobody (the office is not occupied, the Mayor does not exist) mere entailment  mere entailment When did the (current) Mayor of Ostrava visit Prague Q: When did the (current) Mayor of Ostrava visit Prague? A: Never ??? It is not true that the Mayor visited Prague (because the Mayor does not exist) The Mayor did not visit Prague presupposition  presupposition that the Mayor exists

Logic Café14 Two kinds of negation are not equivalent In the logic of partial functions such as TIL these two kinds of negation are not equivalent did not stop Narrow-scope: „X did not stop beating his wife“ It is not true that Wide-scope: „It is not true that X stopped beating his wife“ Presuppositions: X has been married; X did beat his wife; …  NsN: the property of having stopped … is negated  WsN: the entire proposition that X stopped … is negated

Logic Café15 Two kinds of negation Propos.  Presupp.NsNWsN X stopped AX did AX did not stop AIt is not true that X stopped A TTFF FTTT  F  T

Logic Café16 Presupposition of a question  Negative direct answer – only the interpretation applying the narrow scope negation preserving presupposition is adequate Presupposition of an empirical question Q is a proposition P that is entailed by every complete answer corresponding to the respective unambiguous direct answer complete answer  Instead of a wide-scope negation an adequate complete answer is then a negated presupposition I have not been married, I did not beat my wife, The Mayor of Ostrava does not exist, …

Logic Café17 Answering in TIL answer is the negated presupposition  The agent must first check whether the presupposition of a question is true; if it is not so, then the answer is the negated presupposition  If Presupposition than direct answer else negated presupposition

Logic Café18 TIL definition of If P then C else D 1.Make a choice between C and D based on P: [ 0 The_only c [[P  [c = 0 C]]  [P  [c = 0 D]]]] 2.Execute the chosen construction c 2 [ 0 The_only c [[P  [c = 0 C]]  [P  [c = 0 D]]]] The_only is a singulariser function ({ n }   n ) that returns the only construction, the member of a singleton; otherwise undefined c   n : a variable ranging over procedures; 0 C, 0 D: procedures C, D are objects to operate on; Hyperintensional logic is needed to deal with procedures, not only with their products.

Logic Café19 Answering in TIL  If there are some trucks delivering their cargo than T or F according as all of them delivered the cargo, else no trucks (negated presupposition) TIL analysis (schematic): wt If [[ 0 Some 0 Trucks wt ] 0 Delivering wt ]wt If [[ 0 Some 0 Trucks wt ] 0 Delivering wt ] than [[ 0 All 0 Trucks wt ] 0 Delivered wt ] else [[ 0 No 0 Trucks wt ] 0 Delivering wt ] than [[ 0 All 0 Trucks wt ] 0 Delivered wt ] else [[ 0 No 0 Trucks wt ] 0 Delivering wt ]

Logic Café20 Analysis in TIL wt [If 0 x[[ 0 Truck wt x]  [ 0 Deliver wt x 0 Cargo]] then x [[ 0 Truck wt x]  [ 0 Deliver wt x 0 Cargo]] else [ 0  0 Truck wt ]] /(()); Truck/()  ; Deliver/(()  )  ; Cargo/() .

Logic Café21 Presupposition triggers  Topic-focus articulation Topic  presupposition Focus  mere entailment  Interruption/termination of an activity Presupposes that the activity took place  Future/past tenses with reference time The time t of evaluation must be less than / greater than the reference time T  Factiva in attitudes know that, regret that, …  Exclusive-or Just one alternative

Logic Café22 Interruption/termination of an activity  Did Tom find a nearby vacant parking  Did Tom find a nearby vacant parking? Merely entailsdoes not presuppose Merely entails but does not presuppose that a nearby vacant parking exists (Karttunen ‘semifactivum’) Presupposes Presupposes that Tom had been looking for a nearby vacant parking wt [ If t’ [[t’ < t]  [ 0 Seek wt‘ 0 Tom 0 Parking]] then [ 0 Find wt 0 Tom 0 Parking] else t’ [[t’ < t]  [ 0 Seek wt‘ 0 Tom 0 Parking]] ] Types: , /(()); Seek, Find/(()  )  ; Parking/() .

Logic Café23 Dynamic querying; tenses  Another frequent case of queries with presuppositions are queries in future or past tenses with a reference time informing when this or that should happen or happened, respectively. Consider, for instance, this situation:  a sends to b a query-message “Shall we meet today at 4 p.m.?” and  b obtains the message at 5 p.m.  Now b cannot possibly answer Yes or No. Instead, b should inform a that the time of evaluation of this message is greater than the time specified by the message.

Logic Café24 Queries and tenses wt [ If [t < 0 4] then [[[ 0 Meet w] 0 4] a b]  [[ 0 Today t] 0 4]] else [t  0 4] ] Types. 4/t: the time moment 4 p.m. of the respective day; Meet/()  ; Today/(()).

Logic Café25 Conclusion questions presupposition The main contribution is the analysis of questions that come attached with a presupposition. definition of presupposition of a question more accurate By distinguishing two kinds of negation, we managed to make the commonly used definition of presupposition of a question more accurate. appropriate answering reaction Another contribution is the analysis of the appropriate answering reaction. If the presupposition of a question Q is not true, then there is no direct answer, that is, the agent asked cannot convey the value of Q. Instead, the agent informs the inquirer that the presupposition is not true, which makes it possible to adjust the question. presupposition triggers general analytic schema We also considered several presupposition triggers, and using our general analytic schema that applies the strict TIL definition of the ‘if-then-else’ function, we analysed answering these types of questions.

Logic Café26 Thank you for your attention Questions? Answers? Presuppositions !!!