Questions, Answers and
Presuppositions
Marie Duží & Martina Číhalová
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.
Q: Did you stop smoking?
presupposes that you did smoke;
Q: Did all the trucks deliver their cargo?
A: Yes.
Q: Hence all the cargo has been delivered? Yes. …
Presupposition: there were some trucks delivering cargo;
hence there is some cargo delivered.
18. 3. 2016
Logic Café
3
Multi-agent system (MAS)







Taking into account presuppositions of questions is
in particular important in case of building a multiagent system
Autonomous, (less or more) intelligent agents
No central dispatcher
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
18. 3. 2016
Logic Café
4
Multi-agent system (MAS)
Imagine communication not respecting
presuppositions:
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)
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
???

18. 3. 2016
Logic Café
5
QUESTIONS AND ANSWERS

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.
a direct answer to the question Q is a construction of
an -value of Q in a given world-time pair of
evaluation.
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.
18. 3. 2016
Logic Café
6
Wh-questions

Who is ... ?

Who is the Mayor of Ostrava?
wt [0Mayor_ofwt 0Ostrava]  


Which ...?


Which mobile agents are going to Prague?
wt x [[[0Mobile 0Agent]wt x] 
[0Going_towt x 0Prague]]  ()


Types: Mayor_of/(); Ostrava/.
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.)
7
Exclusive-or questions: ..., or... ?
“Is the parking lot P1 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

wt [0I p [[pwt 0P1]  [[p = 0Vacant]  [p = 0Occupied]]]]

18. 3. 2016
Types: p/*1 v (); I/(()(())): the ()singularizer; P1/; Vacant, Occupied/().
Logic Café
8
Presupposition of a question


Standard definition:
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”.
18. 3. 2016
Logic Café
9
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)
18. 3. 2016
Logic Café
10
Presupposition vs. mere entailment
We follow Frege and Strawson in treating
survival under negation as the most important
test for presupposition.
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.
18. 3. 2016
Logic Café
11
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)
18. 3. 2016
Logic Café
12
Two kinds of negation
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
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 that the Mayor exists
18. 3. 2016
Logic Café
13
Two kinds of negation
In the logic of partial functions such as TIL these
two kinds of negation are not equivalent
Narrow-scope: „X did not stop beating his wife“
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
18. 3. 2016
Logic Café
14
Two kinds of negation
Propos.  Presupp.
X stopped A
18. 3. 2016
X did A
NsN
WsN
X did not stop A
It is not true that
X stopped A
T
T
F
F
F
T
T
T

F

T
Logic Café
15
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
Instead of a wide-scope negation an
adequate complete answer is then a
negated presupposition

18. 3. 2016
I have not been married, I did not beat my wife,
The Mayor of Ostrava does not exist, …
Logic Café
16
Answering in TIL


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
18. 3. 2016
Logic Café
17
TIL definition of If P then C else D
1. Make a choice between C and D based on P:
[0The_only c [[P  [c = 0C]]  [P  [c = 0D]]]]
2. Execute the chosen construction c
2[0The_only



18. 3. 2016
c [[P  [c = 0C]]  [P  [c = 0D]]]]
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;
0C, 0D: procedures C, D are objects to operate on;
Hyperintensional logic is needed to deal with
procedures, not only with their products.
Logic Café
18
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):
wt If [[0Some 0Truckswt] 0Deliveringwt]
than [[0All 0Truckswt] 0Deliveredwt]
else [[0No 0Truckswt] 0Deliveringwt]
18. 3. 2016
Logic Café
19
Presupposition triggers

Topic-focus articulation



Interruption/termination of an activity


The time t of evaluation must be less than / greater
than the reference time T
Factiva in attitudes


Presupposes that the activity took place
Future/past tenses with reference time


Topic  presupposition
Focus  mere entailment
know that, regret that, …
Exclusive-or

18. 3. 2016
Just one alternative
Logic Café
21
Interruption/termination of an activity

Did Tom find a nearby vacant parking?


Merely entails but does not presuppose that a nearby
vacant parking exists (Karttunen ‘semifactivum’)
Presupposes that Tom had been looking for a nearby
vacant parking
wt [
If t’ [[t’ < t]  [0Seekwt‘ 0Tom 0Parking]]
then [0Findwt 0Tom 0Parking]
else t’ [[t’ < t]  [0Seekwt‘ 0Tom 0Parking]]
]
Types: , /(()); Seek, Find/(()); Parking/().
18. 3. 2016
Logic Café
22
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.

18. 3. 2016
Logic Café
23
Queries and tenses

wt [
If [t < 04]
then
[[[0Meet w] 04] a b]  [[0Today t] 04]]
else [t  04]
]

18. 3. 2016
Types. 4/t: the time moment 4 p.m. of
the respective day; Meet/();
Today/(()).
Logic Café
24
Conclusion
The main contribution is the analysis of questions that
come attached with a presupposition.
By distinguishing two kinds of negation, we managed to
make the commonly used definition of presupposition of
a question more accurate.
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.
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.
18. 3. 2016
Logic Café
25
Thank you for your attention
Questions?
Answers?
Presuppositions !!!
18. 3. 2016
Logic Café
26