If a valid argument has a false conclusion, then at least one premise must be false. 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.
Can an argument be valid if a premise is false?
FALSE. A valid argument can have false premises; and it can have a false conclusion. But if a valid argument has all true premises, then it must have a true conclusion.
Can a valid argument have one premise?
A premise is a statement in an argument that provides reason or support for the conclusion. There can be one or many premises in a single argument.
Can a valid argument have all false premises but a true conclusion?
5. A valid deductive argument cannot have all false premises and a true conclusion.
What if a premise is false?
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.
What makes a argument 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.
Can an argument be almost valid?
Some arguments, while not completely valid, are almost valid. 10. A strong argument may have true premises and a probably false conclusion.
When an argument is valid and all the premises are true?
All valid arguments have all true premises and true conclusions. All sound arguments are valid arguments. If an argument is valid, then it must have at least one true premise. Every valid argument is a sound argument.
What is an example of an invalid argument?
An argument is said to be an invalid argument if its conclusion can be false when its hypothesis is true. An example of an invalid argument is the following: “If it is raining, then the streets are wet. The streets are wet.
When an argument is valid and its premises are true the argument is called?
More specifically, we ask whether the argument is either deductively valid or inductively strong. A deductive argument is an argument that is intended by the arguer to be deductively valid, that is, to provide a guarantee of the truth of the conclusion provided that the argument’s premises are true.
Can premises be valid?
TRUE: If an argument is sound, then it is valid and has all true premises. Since it is valid, the argument is such that if all the premises are true, then the conclusion must be true. A sound argument really does have all true premises so it does actually follow that its conclusion must be true.
Can an invalid argument be a good argument?
An argument is INVALID just in case it’s NOT VALID.
The truth of the premises doesn’t guarantee the truth of the conclusion. That’s ALL it means to call an argument “invalid”. In particular, it doesn’t imply that the argument is bad. As we’ll see in the next lecture, invalid arguments can still be good arguments.
What does it mean for an argument to be valid or invalid?
A deductive argument is said to be valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. Otherwise, a deductive argument is said to be invalid.
Are all valid arguments good arguments?
‘Valid’ does not necessarily mean good or bad. It just means succeeding in establishing conclusive support for its conclusion. Of course, the premises of this argument are false. But claiming that an argument is valid is not to claim that the premises are true.
How do you determine if an argument is valid or invalid?
Think hypothetically. Ask, “IF the premises are true, are we locked into the conclusion?” If yes, then the argument is valid. If no, then the argument is invalid.
How do you make an invalid argument valid?
To judge if each is valid or invalid, ask the question, “If the premises are true, would we be locked in to accepting the conclusion?” If the answer is “yes,” then the argument is valid. If the answer is “no,” then the argument is invalid.
Can a bad argument be valid?
If the argument is valid, there are two cases: Firstly, the argument has false premises, in which case it is not sound. Game over, the argument is bad. Secondly, all of the argument’s premises are true.
What does it mean to say an argument is valid?
To say that a deductive argument is valid means (1) its conclusion (really) necessarily follows from its premises; To say that a deductive argument is valid means (2) it is impossible for its premises all to be true while the conclusion is false.