Phi 270
Fall 2013
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Phi 270 F10 test 3

F10 test 3 topics

The following are the topics to be covered. The proportion of the test covering each will approximate the proportion of the classes so far that have been devoted to that topic. Your homework and the collection of old tests will provide specific examples of the kinds of questions I might ask.

Analysis. Two sorts of questions are possible here corresponding to the sorts of analyses you have done in chs. 5 and 6: (i) analysis by truth-functional connectives only, with atomic sentences as the ultimate components (the focus would, of course, be on conditionals—i.e., on the symbolic representation of if, only if, and unless) and (ii) analysis using truth-functional connnectives and the ideas of predicates, individual terms, and functors.

In the case of the latter sort of analysis, you might be asked to preserve pronouns, representing them using abstracts and variables. (You will not find questions of this sort in the exams before 2006, but your homework on this topic and exercise 2 for 6.2 provide further examples.)

Synthesis. Again this might take two forms, depending on whether the expressions abbreviated by letters were are complete sentences or were terms, predicates, and functors—i.e., depending on whether the question is directed at ch. 5 or ch. 6.

Derivations. Be able to construct derivations to show that entailments hold and to show that they fail. I may tell you in advance whether an entailment holds or leave it to you to check that using derivations. There will be some derivations where detachment and attachment rules may be used and where they will shorten the proof. But there may be others where you must rely on other rules, either because detachment and attachment rules do not apply or because I tell you not to use them. In particular, be ready to use the rule RC (Rejecting a Conditional) from ch. 5.

In the case of a derivation that includes forms involving predicates and functors, you won’t be asked to present a counterexample if the derivation fails (though you will still need to be able to recognize that such a derivation has failed). In short, the test won’t cover the new material introduced in 6.4.


F10 test 3 questions

Analyze the sentences below in as much detail as possible using only connectives; that is, the unanalyzed components should all be sentences (rather than individual terms, predicates, or functors). Present the result in both symbolic and English notation, rewriting if necessary to make all symbolic conditionals point from left to right. Be sure that the unanalyzed components of your answer are complete and independent sentences; also try to respect any grouping in the English.

1.

They won’t get home early if they go through the city during rush hour.

answer
2.

Unless it was raining, the picnic was postponed only if it was unusually cold.

answer

Use derivations to check whether each of the entailments below holds. You may use detachment and attachment rules. If an entailment fails, confirm a counterexample that lurks in an open gap. (Your truth-table for a counterexample should show the truth-value of each compound component of sentence under the main connective of that component, and it should indicate the final truth-value of each sentence.)

3.

B → (A → C) ⊨ (A ∧ B) → C

answer
4.

A → ¬ C, C → B ⊨ ¬ B → A

answer

Analyze the sentence below in as much detail as possible, giving a key to your abbreviations of unanalyzed expressions. In this case you should identify components that are individual terms, predicates, or functors; however, you do not need to present the result in English notation (i.e., symbolic notation is enough). Your analysis should be in reduced form (i.e., you should not use abstracts and variables), so be sure that the unanalyzed components of your answer are independent—in particular, that none contains a pronoun whose antecedent is in another. (Also be sure also that the individual terms you identify really are individual terms and are not quantifier phrases or general terms like simple common nouns.)

5.

If Al went through Phoenix, he stayed with Barb’s family.

answer

Analyze the sentence below using abstracts and variables to represent pronominal cross reference (instead of replacing pronouns by their antecedents). That is, use expanded form to the extent necessary so that each individual term in your analysis appears only as often as it appears in the original sentence. In other respects, your analysis should be as described for 5.

6.

Ann spoke to Bill, and he introduced himself to Carol.

answer

Use a derivation to show that the entailment below holds. You may use detachment and attachment rules. Be sure to indicate the alias sets whenever an equation is added to the resources.

7.

Ga → a = c, Rb(fa) ⊨ b = c → (Ga → Ra(fb))

answer

F10 test 3 answers

1.

they won’t get home early if they go through the city during rush hour

they won’t get home early ← they will go through the city during rush hour

¬ they will get home early ← they will go through the city during rush hour

¬ E ← R
R → ¬ E
if R then not E

E: they will get home early; R: they will go through the city during rush hour

2.

unless it was raining, the picnic was postponed only if it was unusually cold

¬ it was raining → the picnic was postponed only if it was unusually cold

¬ it was raining → (¬ the picnic was postponed ← ¬ it was unusually cold)

¬ R → (¬ P ← ¬ C)
¬ R → (¬ C → ¬ P)
if not R then if not C then not P

C: it was unusually cold; P: the picnic was postponed; R: it was raining

3.
│B → (A → C)3
├─
││A ∧ B2
│├─
2 Ext││A(4)
2 Ext││B(3)
3 MPP││A → C4
4 MPP││C(5)
││●
│├─
5 QED││C1
├─
1 CP│(A ∧ B) → C
4.
│A → ¬ C4
│C → B2
├─
││¬ B(2)
│├─
2 MTT││¬ C
││
│││¬ A
││├─
│││││¬ A
││││├─
│││││○¬ A, ¬ C, ¬ B ⊭ ⊥
││││├─
│││││⊥5
│││├─
5 IP││││A4
│││
││││¬ C
│││├─
││││○¬ C, ¬ A, ¬ B ⊭ ⊥
│││├─
││││⊥4
││├─
4 RC│││⊥3
│├─
3 IP││A1
├─
1 CP│¬ B → A
ABCA¬C,CB/¬BA
FFFTT
5.

if Al went through Phoenix, he stayed with Barb’s family

Al went through Phoenix → Al stayed with Barb’s family

[ _ went through _ ] Al Phoenix → [ _  stayed with _ ] Al (Barb’s family)

Wap → Sa([ _’s familyBarb)

Wap → Sa(fb)

S: [ _ stayed with _ ]; W: [ _ went through _ to _ ]; a: Al; b: Barb; p: Phoenix; f: [ _’s family]

6.

Ann spoke to Bill, and he introduced himself to Carol

Bill is such that (Ann spoke to him, and he introduced himself to Carol)

[Ann spoke to x, and x introduced x to Carol]x Bill

[Ann spoke to x ∧ x introduced x to Carol]xb

[[ _ spoke to _ ] Ann x ∧ [ _ introduced _ to _ ] x x Carol]xb

[Sax ∧ Ixxc]xb

I: [ _ introduced _ to _ ]; S: [ _ spoke to _ ]; a: Ann; b: Bill; c: Carol

7.
│Ga → a = c3
│Rb(fa)(4)
├─
││b = ca, b–c, fa, fb
│├─
│││Ga(3)
││├─
3 MPP│││a = ca–b–c, fa–fb
│││●
││├─
4 QED=│││Ra(fb)2
│├─
2 CP││Ga → Ra(fb)1
├─
1 CP│b = c → (Ga → Ra(fb))