If an argument is invalid, then it must have at least
one false
premise. If an argument has a conclusion that is certainly false, then the argument must be invalid. If the premises and conclusion are all false, the argument must be invalid. Some invalid arguments have true premises and a true conclusion.
Can a valid argument have a contradiction as a conclusion?
No propositionally valid argument can have
a contradiction as a conclusion. Try writing down the truth table to evaluate the following argument: … There is no assignment of truth values to the sentence letters on which the premise comes out true and the conclusion false.
Does a valid argument have a true conclusion?
FALSE:
A valid argument must have a true conclusion only if all of the premises are true
. So it is possible for a valid argument to have a false conclusion as long as at least one premise is false. 2. A sound argument must have a true conclusion.
Can a valid argument have all false premises but a true conclusion?
TRUE:
A valid argument cannot have all true premises
and a false conclusion. So if a valid argument does have a false conclusion, it cannot have all true premises. Thus at least one premise must be false. … If an invalid argument has all true premises, then the conclusion must be false.
Can a valid deductive argument have false premises and true conclusions?
TRUE. By definition,
a valid argument cannot have a false conclusion and all true premises
. So if a valid argument has a false conclusion it must have some false premise.
What is an invalid conclusion?
By definition,
every argument with true premises and a false conclusion
is INVALID. So is every argument for which we can invent a story in which the premises are true and the conclusion false. … For either example, the logic is invalid but the premises are true. Here the conclusion is false.
What is false conclusion?
n. 1. ( Logic) a
purported refutation of a proposition that does not in fact prove it false
but merely establishes a related but strictly irrelevant proposition.
Can an unsound argument have a true conclusion?
It should be noted that both invalid, as well as valid but
unsound, arguments can nevertheless have true conclusions
. One cannot reject the conclusion of an argument simply by discovering a given argument for that conclusion to be flawed.
Can a cogent argument have a false conclusion?
A cogent inductive argument
What logical conclusion can you draw about an argument that is valid but has a false conclusion?
What logical conclusion can you draw about an argument that is valid but has a false conclusion? This
argument must have at lease one false premise
Can a strong inductive argument have a false conclusion?
An inductive argument is an argument that is intended by the arguer to be strong enough that, if the premises were to be true, then
it would be unlikely that the conclusion is false
. … An inductive argument can be affected by acquiring new premises (evidence), but a deductive argument
What is a valid argument with false premises?
A false premise is an incorrect proposition that forms the basis of an argument or syllogism. Since the premise (proposition, or assumption) is not correct, the conclusion drawn may be in error. However, the logical validity of an argument is a
function of its internal consistency
, not the truth value of its premises.
Can a non deductive argument have false premises?
In a good non-deductive argument, if the premises are all true, you would rightly expect the conclusion to be true also, though you would accept that
it may be false
.
How do you know if a conclusion is valid?
Valid: an argument is valid if and only if it is necessary that
if all of the premises are true
, then the conclusion is true; if all the premises are true, then the conclusion must be true; it is impossible that all the premises are true and the conclusion is false.
How can you tell if an argument is strong or weak?
Definition: A
strong
argument is a non-deductive argument
What is an invalid argument called?
An invalid argument is also known as
a fallacy
. Some authors use the term unsound argument to mean invalid argument. However, because of the confusion about the meaning of sound argument, which can be used to mean either valid argument or proof, it is recommended that this term not be used.
