Phi 270
Fall 2013
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Phi 270 F12 test 2

F12 test 2 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. Be able to analyze the logical form of a sentence as fully as possible using conjunction, negation, and disjunction and present the form in both symbolic and English notation.

Synthesis. Be able to synthesize an English sentence that has a given logical form.

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 may be a derivation where attachment rules (Adj and Wk) and detachment rules (MTP and MPT) may be used and where they will shorten the proof; but there will be other derivations where you must rely on the basic rules, either because detachment and attachment rules do not apply or because I tell you not to use them.

You should also be ready to give the proximate argument of a gap at any stage and to indicate all the rules that might be applied.


F12 test 2 questions

Analyze each sentence below in as much detail as possible, presenting the result using symbolic notation and also using English notation. Provide a key to your abbreviations of unanalyzed components, and be sure that these components are complete and independent sentences. Try to respect any grouping in the English.

1.

Either the president or vice-president was at the meeting, but the secretary hadn’t heard about it.

answer
2.

Although it was neither hot nor sunny, it wasn’t both cold and wet.

answer

Synthesize an English sentence that has the analysis below. Choose a simple and natural sentence whose organization reflects the grouping of the logical form:

3.

¬ (C ∧ D) ∧ ¬ (P ∨ R)

C: Carol attended the meeting; D: Dave attended the meeting; P: Carol’s proposal was approved; R: Dave’s proposal was approved

answer

Use derivations to check whether each of the claims of entailment below holds.

If a derivation fails, confirm a counterexample by providing a table in which you calculate the truth values of the premises and conclusion on an extensional interpretation (i.e., an assignment of truth values) that lurks in an open gap. You should display intermediate steps in your calculation by writing the value of any compound component under the main connective of the component, and you should be sure to mark the final values you have calculated for each of the premises and for the conclusion (e.g., by circling these values).

Do not use attachment or detachment rules in these derivations. That is, do not use Adj or the rules MTP, MPT, and Wk of §4.3; instead use only the basic rules for exploiting resources, planning for goals, and closing gaps.

4. A ∧ ¬ B ⊨ ¬ (A ∧ B)
answer
5. ¬ (A ∧ B) ⊨ ¬ A
answer
6. (A ∧ C) ∨ (C ∧ B) ⊨ C
answer
7. A ∨ (B ∧ C) ⊨ B ∨ A
answer

F12 test 2 answers

1.

either the president or vice-president was at the meeting, but the secretary hadn’t heard about it

either the president or vice-president was at the meeting ∧ the secretary hadn’t heard about the meeting

(the president was at the meeting ∨ the vice-president was at the meeting) ∧ ¬ the secretary had heard about the meeting

(P ∨ V) ∧ ¬ S
both either P or V and not S

P: the president was at the meeting; S: the secretary had heard about the meeting; V: the vice-president was at the meeting

2.

although it was neither hot nor sunny, it wasn’t both cold and wet

it was neither hot nor sunny ∧ it wasn’t both cold and wet

¬ it was either hot or sunny ∧ ¬ it was both cold and wet

¬ (it was hot ∨ it was sunny) ∧ ¬ (it was cold ∧ it was wet)

¬ (H ∨ S) ∧ ¬ (C ∧ W)
both not either H or S and not both C and W

C: it was cold; H: it was hot; S: it was sunny; W: it was wet

[¬ H ∧ ¬ S is also correct as an analysis of the first conjunct, and ¬ C ∨ ¬ W is a correct (though less likely) analysis of the second; however, ¬ H ∨ ¬ S and ¬ C ∧ ¬ W are not correct.]

3.

¬ (C ∧ D) ∧ ¬ (P ∨ R) with
C: Carol attended the meeting; D: Dave attended the meeting; P: Carol’s proposal was approved; R: Dave’s proposal was approved

¬ (Carol attended the meetingDave attended the meeting) ∧ ¬ (Carol’s proposal was approvedDave’s proposal was approved)

¬ Carol and Dave both attended the meeting ∧ ¬ either Carol’s or Dave’s proposal was approved

Carol and Dave didn’t both attend the meeting ∧ neither Carol’s nor Dave’s proposal was approved

Carol and Dave didn’t both attend the meeting, and neither’s proposal was approved

4.
│A ∧ ¬ B1
├─
1 Ext│A
1 Ext│¬ B(4)
││A ∧ B3
│├─
3 Ext││A
3 Ext││B(4)
││●
│├─
4 Nc││⊥2
├─
2 RAA│¬ (A ∧ B)
5.
│¬ (A ∧ B)2
├─
││A(4)
│├─
││││●
│││├─
4 QED││││A3
│││
│││││¬ B
││││├─
│││││○¬ B, A ⊭ ⊥
││││├─
│││││⊥5
│││├─
5 IP││││B3
││├─
3 Cnj│││A ∧ B2
│├─
2 CR││⊥1
├─
1 RAA│¬ A
 
AB ¬(AB) / ¬A
TF F
6.
│(A ∧ C) ∨ (C ∧ B)1
├─
││A ∧ C2
│├─
2 Ext││A
2 Ext││C(3)
││●
│├─
3 QED││C1
││C ∧ B4
│├─
4 Ext││C(5)
4 Ext││B
││●
│├─
5 QED││C1
├─
1 PC│C
7.

The following are two possible answers, but there are others:

 
│A ∨ (B ∧ C)1
├─
││A(3)
│├─
│││¬ B
││├─
│││●
││├─
3 QED│││A2
│├─
2 PE││B ∨ A1
││B ∧ C4
│├─
4 Ext││B(6)
4 Ext││C
││
│││¬ A
││├─
│││●
││├─
6 QED│││B5
│├─
5 PE││B ∨ A1
├─
1 PC│B ∨ A
│A ∨ (B ∧ C)2
├─
││¬ B(6)
│├─
│││A(3)
││├─
│││●
││├─
3 QED│││A2
││
│││B ∧ C4
││├─
4 Ext│││B(6)
4 Ext│││C
│││
││││¬ A
│││├─
││││●
│││├─
6 Nc││││⊥5
││├─
5 IP│││A2
│├─
2 PC││A1
├─
1 PE│B ∨ A