Question

Difficulty: EasyParallel Reasoning and Parallel Flaw

Pair each of the following short deductive arguments with the statement that most accurately characterizes its logical form or reasoning defect.

  • Every homeowner who installs solar panels lowers their monthly utility bill. David did not lower his monthly utility bill; therefore, David did not install solar panels.Valid deductive reasoning that infers the absence of an initial condition from the established absence of its necessary result.
  • A theatrical production will be profitable only if it receives positive opening reviews. The new musical received glowing opening reviews; therefore, the musical will be profitable.Flawed reasoning that treats a factor required for an outcome as sufficient to guarantee that the outcome occurs.
  • The municipal museum must either raise general admission prices or reduce public operating hours. The board of directors voted against raising admission prices; therefore, the museum must reduce operating hours.Flawed reasoning that concludes a single outcome must occur by presuming without justification that only two mutually exclusive alternatives exist.

Answer

The solar panel argument pairs with the statement describing valid deduction from the absence of a necessary result; the theatrical production argument pairs with the statement describing the error of treating a required condition as a guarantee; and the museum argument pairs with the statement describing an unjustified assumption of only two exclusive alternatives.
Each argument corresponds to its exact structural form: the solar panel argument validly concludes the absence of an initial condition because its necessary result did not happen; the theatrical production argument commits a conditional reversal error by treating a requirement as a guarantee; and the museum argument commits a false dilemma by arbitrarily restricting all possibilities to two choices.

Step-by-Step Solution

1
Examine the formal conditional logic of the solar panel argument
The argument establishes that installing solar panels guarantees lower utility bills (P→QP \rightarrow Q), observes that the bill was not lowered (¬Q\neg Q), and validly concludes no solar panels were installed (¬P\neg P).
Maps the first argument to valid contrapositive deduction (modus tollens).
2
Examine the conditional indicator words in the theatrical production argument
The phrase 'only if' introduces a necessary condition (Profitable →\rightarrow Positive Reviews). Concluding profitability from positive reviews treats a necessary condition as sufficient.
Maps the second argument to the fallacy of affirming the consequent / mistaking a necessary condition for a sufficient condition.
3
Examine the disjunctive structure of the municipal museum argument
The argument asserts an 'either/or' premise without demonstrating that other budgetary actions are impossible, then eliminates one option to force the other.
Maps the third argument to the false dilemma fallacy.

Key Concept

Identifying and differentiating valid conditional structures (modus tollens) from canonical reasoning flaws including necessary-versus-sufficient confusion and false dilemma.
Estimated Time:1m 0s
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