- Read pp.154–170 in Language Files.
- Submit Blog Post #3 by 11:59pm on Friday, April 12th:
As discussed in class and the reading, a proposition makes a claim that may be either true or false. Often, we don’t actually know the “truth value” of a proposition – i.e. whether it is true or false – but we do know the “truth conditions” – i.e. what it would take for that proposition to be true. We also know what it would entail – i.e. what other statements would have to be true – if that proposition were true.
For example, take the proposition “Joe Pentangelo ate scrambled eggs for breakfast today.” You don’t know its truth value: it may be true or false. Maybe I did, maybe I didn’t. But you know the truth conditions – it would be true if and only if I really did eat scrambled eggs for breakfast. You also know that there are a few other propositions that must be true if that one is, like “Joe Pentangelo ate breakfast,” “Joe Pentangelo ate eggs,” and “Joe Pentangelo ate today.”
For this post, write three separate propositions, one of which you know to be true, one of which you know to be false, and one of which you don’t know the truth value of. For each proposition, write out its truth conditions, as well as one other proposition that it entails – a sentence that would have to be true if the original sentence were true (even for the one you know isn’t).
For a full example, this would be a successful post:
- Proposition: I have two cats.
- Truth value: True.
- Truth conditions: In order for this to be true, I need to own and live with two cats.
- Entailment: “I have two cats” entails “I have at least one cat.”
- Proposition: I have a nose ring.
- Truth value: False.
- Truth conditions: I would have to actually have a nose piercing with a ring in it.
- Entailment: “I have a nose ring” entails “My nose is pierced.”
- Proposition: There is life on Mars.
- Truth value: Unknown.
- Truth conditions: For this to be true, there would have to be at least one living organism on the planet of Mars.
- Entailment: “There is life on Mars” would entail “There is life on a planet other than earth.”
Blog Post #3:
Proposition: I have a pool.
Truth value: True
Truth Conditions: I would actually have to own a pool on my property.
Entailment: “I have a pool” entails that “I have a backyard”.
Proposition: I have blue eyes.
Truth Value: False
Truth Conditions: My eye color would actually have to be blue.
Entailment: “I have blue eyes” entails that “I have the blue eyes gene passed down from my parents”.
Proposition: There is a species of fish living in the ocean that humans have never discovered.
Truth Value: Unknown
Truth Conditions: For this to be true, there would have to be at least on undiscovered species of fish in the ocean.
Entailment: “There is a species of fish living in the ocean that humans have never discovered.” entails “There is a fish that has yet to be discovered and or studied by humans.”