Math Problem Statement

Determine which of the following are valid arguments: a) p → q, p ∧ q, therefore q. b) I studied. Either I studied or I passed the exam. If I passed the exam, then I did not study. Therefore, I studied.

Solution

Let's analyze the two arguments provided in the image to determine if they are valid.

Argument (a)

The structure of this argument is:

  1. pqp \rightarrow q (If pp, then qq)
  2. pqp \land q (Both pp and qq are true)
  3. Therefore, qq

This argument is valid because the premises directly support the conclusion.

  • pqp \rightarrow q means if pp is true, qq must be true.
  • pqp \land q states both pp and qq are true, so qq is confirmed to be true.

This is an example of modus ponens and conjunction elimination, both valid logical inferences.

Argument (b)

The structure of this argument is more verbal:

  1. "I studied."
  2. "Either I studied or I passed the exam."
  3. "If I passed the exam, then I did not study."

Conclusion: "I studied."

This argument is a bit tricky. We can formalize it as follows:

  • Let SS represent "I studied" and PP represent "I passed the exam."
  • Premise 1: SS (I studied).
  • Premise 2: SPS \lor P (Either I studied or I passed the exam).
  • Premise 3: P¬SP \rightarrow \neg S (If I passed the exam, then I did not study).

In this case, the argument is also valid because:

  • Premise 1 already asserts SS (I studied), which satisfies the conclusion directly.
  • The third premise P¬SP \rightarrow \neg S doesn't contradict this, as there's no indication that PP is true; in fact, PP must be false because SS is true (as stated in premise 1). Therefore, P¬SP \rightarrow \neg S is vacuously true.

Conclusion:

  • Both arguments (a) and (b) are valid. Thus, the correct answer is A) Both a and b.

Would you like further details on any step of this analysis?

Here are 5 related questions to further explore this topic:

  1. What is the difference between a valid argument and a sound argument?
  2. Can you explain how modus ponens works in more detail?
  3. How does the truth table for pqp \rightarrow q look?
  4. What are some common logical fallacies in reasoning?
  5. How can a vacuous truth make an argument valid?

Tip: When analyzing logical arguments, always look for the structure and relationships between premises to determine their validity.

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Math Problem Analysis

Mathematical Concepts

Propositional Logic
Logical Validity
Modus Ponens
Conjunction Elimination

Formulas

p → q
p ∧ q
S ∨ P
P → ¬S

Theorems

Modus Ponens
Conjunction Elimination
Vacuous Truth

Suitable Grade Level

Grades 10-12