Ling 442

1
Lecture 6

• Ling 442

2
Exercises (part 1)

• Why do the following two sentences have the same
  truth conditions?
• You must not smoke here.
• You may not smoke here.

3
Exercises (part 2)
?

• Formalize the following using ??.
• Necessarily, a bachelor is unmarried.
• A child could have invented the mousetrap.
• The lake is sure to freeze tonight.
• Right-turning traffic must give way.
• Discuss the differences between 1 and 2
• If Cain didnt kill Abel, then someone else did.
• If Cain hadnt killed Abel, then someone else
  would have.

4
Cross-linguistic data

• In Japanese, the concepts associated with deontic
  must/may and epistemic must/may are conveyed by
  two separate forms
• (approximate translations into English)
• Deontic must If you do not do it, it is no good.
• Epistemic must It is not wrong that S.
• Deontic may Even if you do it, it is good.
• Epistemic may It is not known if S.
• How about your language (if it is not English)?

5
Modal Perfect

• In principle, any modal verb is ambiguous between
  epistemic and deontic readings. But complex forms
  (modal perfect) often lack deontic readings.
• In order to take Ling 479, You must have taken
  L442. (deontic ok)
• ?? An applicant to our graduate program may have
  been a member of another program. (deontic
  presumably impossible)

6
Epistemic vs. Counterfactual Possibilities

• Nice example from the text
• She might have fallen down the cliff. (Ambiguous
  between an epistemic reading and a counterfactual
  (Kearns calls it logical) reading.
• If you have difficulty finding two readings, then
  try using could.
• She could have fallen down the cliff.

7
Counterfactual conditions in more detail

• The semantics of counterfactual conditionals
  cannot be stated in terms of the truth values of
  the component sentences.
• You need to say something like the following
• ?If S1, then S2? true iff in all possible worlds
  w most similar to the actual world among those in
  which ?S1? true, ?S2? true as well.