Phi 270
Fall 2013
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Phi 270 F10 test 4

F10 test 4 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 ready to handle any of the key issues discussed in class—for example,

the proper analysis of every, no, and only (see §7.2.2),

how to incorporate bounds on complementary generalizations (see §7.2.3),

ways of handling compound quantifier phrases (such as only cats and dogs, see §7.3.2),

the distinction between every and any (see §§7.3.3 and 7.4.2),

how to analyze multiple quantifier phrases with overlapping scope (see §7.4.1).

You should be able restate your analysis using unrestricted quantifiers (see §7.2.1), but you will not need to present it in English notation.

Synthesis. You may be given a symbolic form and an interpretation of its non-logical vocabulary and asked to express the sentence in English. Remember that the distinction between every and any can be important here, too.

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. If a derivation fails, you may be asked to present a counterexample, which will involve describing a structure. You will not be responsible for the rules introduced in §7.8.1.


F10 test 4 questions

Analyze the sentences below in as much detail as possible, providing a key to the non-logical vocabulary you use. Also restate your analyses using unrestricted quantifiers.

1.

No one was disappointed.

answer
2.

If any part was missing, the set wasn't assembled.

answer
3.

Only cartoons appealed to everyone.

answer

Synthesize an English sentence that has the following logical form; that is, devise a sentence that would have the following analysis:

4.

¬ (∀x: Jx ∧ ¬ Sx) ¬ Fx

F: [ _ was finished]; J: [ _ is a job]; S: [ _ is small]

answer

Use derivations to show that the following arguments are valid. You may use any rules.

5.
∀x Mx
∀x (Mx → Qx)
∀x Qx
answer
6.
∀x ∀y (Fx → Gy)
Fa → ∀x Gx
answer

Use a derivation to show that the following argument is not valid and present a counterexample that lurks in an open gap. (You may present the counterexample either by a diagram or by tables.)

7.
Rab
∀x Rxa
∀x Rxb
answer

F10 test 4 answers

1.

no one was disappointed.

no one is such that (he or she was disappointed)

(∀x: x is a person) ¬ x was disappointed

(∀x: Px) ¬ Dx
∀x (Px→ ¬ Dx)

D: [ _ was disappointed]; P: [ _ is a person]

2.

if any part was missing, the set wasn't assembled

every part is such that (if it was missing, the set wasn't assembled)

(∀x: x is a part) if x was missing, the set wasn't assembled

(∀x: Px) (x was missing → the set wasn't assembled)

(∀x: Px) (Mx → ¬ the set was assembled)

(∀x: Px) (Mx → ¬ As)
∀x (Px → (Mx → ¬ As))

A: [ _ was assembled]; M: [ _ was missing]; P: [ _ is a part]; s: the set

3.

only cartoons appealed to everyone

only cartoons were such that (they appealed to everyone)

(∀x: ¬ x is a cartoon) ¬ x appealed to everyone

(∀x: ¬ Cx) ¬ everyone is such that (x appealed to him or her)

(∀x: ¬ Cx) ¬ (∀y: y is a person) x appealed to y

(∀x: ¬ Cx) ¬ (∀y: Py) Axy
∀x (¬ Cx → ¬ ∀y (Py → Axy))

A: [ _ appealed to _ ]; C: [ _ is cartoon]; P: [ _ is a person]

4.

¬ (∀x: x is a job ∧ ¬ x is small) ¬ x was finished

¬ (∀x: x is a job ∧ x isn’t small) x was unfinished

¬ (∀x: x is a job that isn’t small) x was unfinished

¬ every job that isn’t small it such that (it was unfinished)

¬ every job that isn’t small was unfinished

not every job that isn’t small was unfinished
or: among jobs not only small ones were finished
or: not only small jobs were finished
or: it’s false that no jobs that are not small were finished

5.
│∀x Mxa:2
│∀x (Mx → Qx)a:3
├─
│ⓐ
2 UI││Ma(4)
3 UI││Ma → Qa4
4 MPP││Qa(5)
││●
│├─
5 QED││Qa1
├─
1 UG│∀x Qx
6.
│∀x ∀y (Fx → Gy)a:3
├─
││Fa(5)
│├─
││ⓑ
3 UI│││∀y (Fa → Gy)b:4
4 UI│││Fa → Gb5
5 MPP│││Gb(6)
│││●
││├─
6 QED│││Gb2
│├─
2 UG││∀x Gx1
├─
1 CP│Fa → ∀x Gx
7.
│Rab
│∀x Rxaa:2, b:3, c:4
├─
│ⓒ
2 UI││Raa
3 UI││Rba
4 UI││Rca
││
│││¬ Rcb
││├─
│││○¬ Rcb, Rca, Rba, Raa, Rab ⊭ ⊥
││├─
│││⊥5
│├─
5 IP││Rcb1
├─
1 UG│∀x Rxb

Counterexample presented by a diagram

Counterexample presented by tables

abc
123
R 1 2 3
1 T T F
2 T F F
3 T F F