1) Intro to Validity

Question 1

What is a declarative sentence

Answer 1

Sentences that are true or false

Question 2

How many conclusions can an argument have

Answer 2

One

Question 3

How can an argument be logically valid

Answer 3

if and only if there is no interpretation under which the premisses are all true and the conclusion is false

Question 4

How can a conclusion be false

Answer 4

if at least one premise is false, or the argument is invalid

Question 5

Propositionally valid

Answer 5

no interpretation of the sentences such that all premises are true and yet conclusion is false

Question 6

Consistency

Answer 6

set of sentences are consistent if and only if there is at least one interpretation under which all sentences of the set are true

Question 7

Logical Truth

Answer 7

a sentence is logically true if an only if it is true under any interpretation

Question 8

Logically false

Answer 8

a sentence is logically true if an only if it is true under any interpretation

Question 9

Logically Equivalent

Answer 9

Sentences are logically equivalent if an only if they are true under exactly the same interpretations

Question 10

Enthymeme

Answer 10

Collection of sentences which need one more premise and could be true