Conditional Statments and Truth Value

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Discussion Overview

The discussion revolves around the logical implications of conditional statements, specifically the truth values of statements in the form P ⊃ Q. Participants explore the logical soundness of these statements, their interpretations, and related concepts such as set containment.

Discussion Character

  • Exploratory
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants express confusion about why P ⊃ Q is considered true when P is false and Q is true, questioning the logical foundations of this interpretation.
  • Others introduce the concept of set containment (P ⊂ Q) to illustrate that it is possible for P to be false while Q remains true, suggesting a parallel between logical statements and set theory.
  • A participant provides examples to clarify their understanding, using the statements "If the moon is blue then the Earth is round" and "If the moon is not blue then the Earth is round" to illustrate their reasoning about truth values.
  • There is mention of the paradox of the material conditional and the role of modal operators in determining the truth of implications.
  • Some participants propose a specific example using sets to further explore the relationship between P and Q, indicating a willingness to think through the implications of their definitions.

Areas of Agreement / Disagreement

Participants generally express confusion and seek clarification on the topic, indicating that multiple competing views remain regarding the interpretation of conditional statements and their truth values.

Contextual Notes

There are unresolved assumptions about the definitions of P and Q, as well as the implications of their truth values in both logical and set-theoretical contexts.

toboldlygo
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So, I know that P ⊃ Q is a true statement even if P is false as long as Q is true. However, I don't understand why that is, or how that is logically sound. Is it because I'm stuck in thinking of these types of statements as "If P, then Q," and they are not supposed to be thought of that way? How else can I approach this to have it make logical sense to me? Thanks. Also, I'm sorry if this is supposed to go to the HW section (I thought this fit here); please let me know and I'll move it.
 
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Given the statement P⊂Q (i.e., the elements of the set P are contained in the set Q),
it is not illogical to have an event where P is false and Q is true.

It could be the case that there are multiple elements in the set Q that are not also in the set P.
If that were the case, than an event could be in Q and not in P.
 
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toboldlygo said:
So, I know that P ⊃ Q is a true statement even if P is false as long as Q is true. However, I don't understand why that is, or how that is logically sound. Is it because I'm stuck in thinking of these types of statements as "If P, then Q," and they are not supposed to be thought of that way? How else can I approach this to have it make logical sense to me? Thanks. Also, I'm sorry if this is supposed to go to the HW section (I thought this fit here); please let me know and I'll move it.

If the moon is blue then the Earth is round.
If the moon is not blue then the Earth is round.
THEREFORE
The Earth is round.
If the first statement were false, then the deduction wouldn't follow.
 
jfizzix said:
Given the statement P⊂Q (i.e., the elements of the set P are contained in the set Q),
it is not illogical to have an event where P is false and Q is true.
I really like thinking of it this way! Would it be accurate, then, for me to think of it like this: if P = {a, b, c} and Q = {P, d}, then P can be false even if Q is true?
 
See also the paradox of the material conditional. There are modal operators where ## p \rightarrow q## only if q can be derived logically from p.
 
toboldlygo said:
I really like thinking of it this way! Would it be accurate, then, for me to think of it like this: if P = {a, b, c} and Q = {P, d}, then P can be false even if Q is true?
Yes.
 
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