Problem 61 - Thinking Mathematically

Question

Billy Hayes, author of Midnight Express, told a college audience of his decision to escape from the Turkish prison in which he had been confined for five years: "My thoughts were that if I made it, I would be free. If they shot and killed me, I would also be free." (Source: Rodes and Pospesel, Premises and Conclusions, Pearson, 1997) Hayes's dilemma can be expressed in the form of an argument: If I escape, I will be free. If they kill me, I will be free. I escape or they kill me. \(\therefore\) I will be free. Translate this argument into symbolic form and determine whether it is valid or invalid.

Step-by-Step Solution

Answer

The symbolic form of the argument is \(((P \to R) \land (Q \to R) \land (P \vee Q)) \to R\). The argument is valid because the conclusion 'I will be free' is true whether 'I escape' or 'They kill me' is true.

Step 1: Assign Symbols to Each Statement

The first step is to assign symbols to each statement. Let \(P\) represent 'I escape', \(Q\) represent 'They kill me', and \(R\) represent 'I will be free'.

Step 2: Translate the Argument into Symbolic Form

Following the assignment of symbols, we can now represent the argument in symbolic form. The statement 'If I escape, I will be free' becomes \(P \to R\), 'If they kill me, I will be free' becomes \(Q \to R\), and 'I escape or they kill me' becomes \(P \vee Q\). Therefore, combining these, the entire argument in symbolic form is \(((P \to R) \land (Q \to R) \land (P \vee Q)) \to R\)

Step 3: Determine the Validity

Given that the laws of logic dictate that if both the premises are true, then the conclusion must also be true for the argument to be valid. Here, irrespective of whether 'I escape' or 'They kill me' are true, 'I will be free' is a true statement in both the cases. Therefore, the argument is valid.

Key Concepts

Logical Argument

A logical argument is a structured reasoning process designed to arrive at a conclusion based on a series of premises. In the case of Billy Hayes's dilemma, the components of the argument are clearly laid out with each premise leading to a logical conclusion. Each piece of information, such as "If I escape, I will be free," sets the stage for deriving the final outcome.
Logical arguments are a cornerstone in critical thinking, allowing individuals to assess the strength and soundness of a reasoning process. They help in refining thoughts and making informed decisions.

Validity

Validity in symbolic logic refers to a property of arguments whereby if the premises are true, the conclusion must also be true. For an argument to be valid, there cannot be a scenario where the premises are true, yet the conclusion is false.
In the example of Hayes's argument, regardless of whether he escapes or is shot, he ends up being free. This results in a consistently true conclusion based on the given premises, ensuring the argument's validity.

• Premise 1: If I escape, I will be free.
• Premise 2: If they kill me, I will be free.
• Conclusion: I will be free.

The logical structure and consistency in premise truth lead to a confirmed validity of the argument.

Logical Statements

Logical statements are declarative sentences that express a fact or a proposition. Each logical statement holds a truth value, meaning it can either be true or false. In symbolic logic, statements are usually denoted by letters such as \(P\), \(Q\), and \(R\), representing different propositions.
For the argument about Hayes, each declarative sentence is assigned a symbol:

• \(P:\) I escape.
• \(Q:\) They kill me.
• \(R:\) I will be free.

These symbols allow us to manipulate and analyze the argument using logical rules without cumbersome language. Identifying these statements correctly is crucial for constructing and evaluating logical arguments.

Dilemma

A dilemma is a situation where there are two or more options, and each option leads to the same or similar consequence. Hayes's dilemma neatly fits this notion, as he perceives that whether he escapes or is killed, the outcome is that he will be free.
In logical terms, dilemmas are often represented by a disjunction (\(\vee\)) indicating that one of several possibilities must be true. This reflects the structure:

• If I escape, then I will be free.
• If they kill me, then I will be free.
• I escape or they kill me.

Here, regardless of the path taken, the result remains the same, which is characteristic of a dilemma. It plays a vital role in forming compelling arguments where the outcome is independent of specific events.

Symbolic Representation

Symbolic representation in logic allows complex arguments to be expressed and analyzed more efficiently. By translating statements into symbols, we reduce ambiguity and streamline the examination of logical structure.
The argument regarding Hayes uses symbols like \(P\) for 'Escape', \(Q\) for 'Kill', and \(R\) for 'Free'. With these, the argument is expressed as \(((P \to R) \land (Q \to R) \land (P \vee Q)) \to R\). This symbolic translation helps in quickly checking the validity of logic through established logical laws and methods.
Using symbolic representation aids in visualizing logical flow and facilitates easier manipulation in argument evaluation. It is fundamental in converting everyday language into a precise scientific form.