Unit 2: Statements (Lessons 6 & 7)
List the three kinds of self-supporting statements.
1. Self-Reports 2. True or False by Logical Structure 3. True or False by Definition
What are the two types of statements?
1. Self-Supporting Statements 2. Supported Statements.
What is the definition of a statement?
A sentence that has a truth value.
What is a Self-Report?
A statement a person makes about his own thoughts, beliefs or feelings.
What is a Self-Contradiction?
A statement that is always false because of its logical structure.
What is a "tautology"?
A statement that is always true because of its logical structure.
Define a self-supporting statement
A statement whose truth value can be determined from the statement itself. (No outside information is needed to determine if it is true or false.)
What is the Truth Value of a Self-Contradiction?
False because a statement cannot be both true and false at the same time and in the same sense.
Is the following sentence a statement: "Eat your spinach."
No because it is a command and commands do not have a truth value.
Is the following sentence a statement: "The flip will squirt a cruise yesterday in the bright despair."
No because it is a nonsense sentence and does not have a truth value.
Is the following sentence a statement? "What year was Socrates born?"
No because it is a question, and questions do not have a truth value.
What types of sentences are NOT statements?
Questions, Commands and Nonsense Sentences.
Is this the form of a Tautology or a Self-Contradiction: "S is P" and "S is not P"
Self-Contradiction
Is this the form of a Tautology or a Self-Contradiction: "S is P" or "S is not P"
Tautology
What type of self-supporting statement is this: "I think it will rain this afternoon."
This is a "Self-Report".
What type of self-supporting statement is this: "A hat is an article of clothing worn on the feet."
This is a statement that is "False by Definition".
What type of self-supporting statement is this: "The sun is shining and it is not."
This is a statement that is "False by Logical Structure" which is called a "Self-Contradiction".
What type of self-supporting statement is this: "Bachelors are unmarried."
This is a statement that is "True by Definition".
What type of self-supporting statement is this: "The coin will come up heads or not heads."
This is a statement that is "True by Logical Structure" which is called a "Tautology".
What is the Truth Value of a Tautology?
True because it allows for all possibilities.
What is the Truth Value of a Self-Report?
True because we assume that what a person reports about himself is always true.
What are the possible truth values of a statement?
True or False
Is the following sentence a statement: "Shakespeare wrote many plays."
Yes because it has a truth value (true).
