Invalid arguments
![invalid arguments invalid arguments](https://image.slidesharecdn.com/validity-of-argument-170714143937/95/validity-of-argument-8-638.jpg)
Here's an example of an INVALID argument: Validity is the strongest possible logical glue you can have between premises and conclusion. These are all different ways of saying the same thing.
![invalid arguments invalid arguments](https://image.slidesharecdn.com/validinvalidarguments-151126143119-lva1-app6891/95/valid-amp-invalid-arguments-16-638.jpg)
Or to put it another way, the truth of the premises guarantees the truth of the conclusion.
![invalid arguments invalid arguments](https://embed-ssl.wistia.com/deliveries/8682ce04f0d6cb0a541084059e60c7ebd6a525e7.jpg)
THAT is the distinctive property of this argument that we're pointing to when we call it “valid” - that it's logically impossible for the premises to be true and the conclusion false. In other words, in a hypothetical world where all actors are robots, and Tom Cruise also happens to be an actor, then it's logically impossible for Tom Cruise NOT to be a robot. In this case we know that in fact the first premise is false (not all actors are robots) but the argument is still valid because IF the premises were true it would be IMPOSSIBLE for the conclusion to be false. IF all the premises are true, then the conclusion CANNOT be false. Here's the standard definition of a valid argument:Īn argument is VALID if it has the following hypothetical or conditional property: Together, these two concepts, validity and strength, will help us to specify precisely what it means for an argument to satisfy the Logic Condition. In the next lecture we'll talk about "strength" and the difference between "strong" versus "weak" arguments. In this lecture we're going to talk about "validity" and the difference between "valid" versus "invalid" arguments. Valid arguments have the strongest logical glue possible. "Validity" and "strength" are technical terms that logicians and philosophers use to describe the logical "glue" that binds premises and conclusions together. Another way is if the argument is strong. But there are two importantly different ways in which an argument can satisfy the Logic Condition. The color of my car is one of the three primary colors" shows an argument with true premises and a true conclusion that is valid.An argument has to satisfy the Logic Condition in order for it to qualify as a good argument. Therefore, it the premises are true then the conclusion must be a logical consequence of those premises. The sky isn't the same color as my favorite color"īy definition, any argument is valid if the conclusion must be true in any circumstance in which the premises are true. It can also be found when the conclusion contradicts the premises, for example "The sky is blue. For example "Barack Obama is the president. This is most commonly found with arguments that state two premises and have a completely unrelated conclusion. Fidel Castro must be a naturalized US citizen" we can see that although the argument has false premises the conclusion would be a logical consequence if the premises were true.īy definition, any argument with true premises and a false conclusion must be considered invalid. In the example "The president of Cuba must be a naturalized US citizen.
![invalid arguments invalid arguments](https://i.ytimg.com/vi/UTm75PK8uSs/maxresdefault.jpg)
Bluegrass must be orange" displays an argument that has false premises and a false conclusion based upon those false premises that still maintains its validity because the conclusion would be a logical consequence IF the premises were actually true.Ī valid argument may have false premises and still be a valid argument. I have an assignment that asks: Can an argument have false premises and a false conclusion and still be valid? false prem and a true conclusion? true prem and a true conclusion? true prem and a false conclusion?Ī valid argument can have false premises and a false conclusion while still maintaining its validity.