How to Analyze an Argument?

Identifying Indicator Words

 Context: you are thinking about getting a pet and have asked a friend whether you should get a cat or a pet rock.

“Wow, that’s a weird question, but here goes.  Rocks do not make good pets because they lack an emotional life.  Besides, rocks do not have a heartbeat.”

1) underline indicator words, 2) label premises and conclusions, 3) identify any noise, 4) identify any hidden premises or conclusions, 5) diagram the argument.

“Wow, that’s a weird question, but here goes (noise).  Rocks do not make good pets (C) because (premise indicator) they lack an emotional life (P1).  Besides, (indicates an independent premise is coming) rocks do not have a heartbeat (P2).”

Hidden (missing, implicit) premises: ask yourself what linked premises would have to be added to the explicit premises to make them deductive inferences? …

… If, then clauses

Hidden main conclusion: given the context, what further conclusion follows from the conclusion that rocks do not make good pets?

How do we represent that context with a further hidden premise?

“Wow, that’s a weird question, but here goes (noise).  Rocks do not make good pets (C) because (premise indicator) they lack an emotional life (P1).  Besides, (indicates an independent premise is coming) rocks do not have a heartbeat (P2).”

HP3: If it does not have an emotional life, then it does not make a good pet – linked to P1

HP4: If it does not have a heartbeat, then it does not make a good pet – linked to P2

HP5: You are getting either a cat or a pet rock – linked to C

HMC: You should get a cat.

Symbolize: 1) bracket propositions, 2) underline logical connectives, 3) symbolize both sub-arguments and prove their validity

“Rocks do not make good pets because they lack an emotional life. You see, if it does not have an emotional life, then it does not make a good pet.

“Rocks do not make good pets because they do not have a heartbeat.  And if it does not have an a heartbeat, then it does not make a good pet.”

Bracket the propositions, underline the logical connectors, assign the variables, symbolize the argument, and provide the proof.

If the government minister is not honest, she is not to be trusted, and if she’s not to be trusted, she should not hold a government post and should be sent back to her law firm. I know that the minister is not honest.  So she should be sent back to her law firm.

1. Symbolize the following arguments and determine whether they are a validconditional schemas (affirming the antecedent, denying the consequent, conditional series) or invalidones (affirming the consequent and denying the antecedent).  Begin by bracketing the propositions and underlining the logical connectives.

1) If the weather is good this year, the crops will be better than last year.  The weather is good this year.  Therefore, the crops will be better than last year. (w, c)

2) If the weather is good this year, the crops will be better than last year.  The crops will be better than last year.  Therefore, the weather is good this year. (w, c)

3)  If the weather is good this year, the crops will be better than last year.  The crops will not be better than last year.  Therefore, the weather is not good this year. (w, c)

4) If the weather is good this year, the crops will be better than last year.  The weather is not good this year.  Therefore, the crops will not be better than last year. (w, c)

5) If the weather is good this year, the crops will be better than last year.  If the crops will be better than last year, then we will make a profit.  Therefore, if the weather is good this year, we will make a profit.