Section C of Chapter 3 discusses how we can logically distinguish an argument as either "valid" or "invalid", as well as identifying arguments as either a "strong" argument or a "weak" argument. The book gives us three guidelines that an argument must pass in order to be a good argument.
These guidelines are:
1) The premises are plausible.
2) The premises are more plausible than the conclusion.
3) The argument is valid or strong.
Here's a hypothetical argument:
Bobby is a teenager.
Every teenager plays video games.
Therefore, Bobby plays video games.
First off, this argument is valid (test #3). Like the book says, there's no possible way the premises can be true and the conclusion be false. However, it's not a strong argument as the second premise is false.
*Note: An argument only has to pass one of the tests to be a good argument. As the book states, they are independent from each other.
I could go on to test the argument using the other two guidelines, but I don't necessarily need to. In reference to #1) The first premise is plausible yes, but the second isn't. In reference to #2) it's more plausible for a teenager "Bobby" to play video games than it is for EVERY teenager out there to play video games. This argument is valid, but it is a bad argument.
When we evaluate arguments, we look at several things. We look to make sure the premises are plausible, we look to make sure the premises and the conclusion make sense, and we look at any possibilites for the premises to be true and the conclusion to be false. The more specific the argument is, the better chance you have to convince someone.
For example:
Stephen rides motorcross. Stephen hurt his arm. Stephen hurt his arm dirt biking.
This argument isn't specific at all. It's not strong as it's entirely possible for the premises to be true and the conclusion be false. His arm could have been injured skateboarding or doing another activity.
The preferred argument would be:
Stephen crashed while riding his dirt bike.
Stephen's arm only started hurting after his dirt bike crash.
Therefore, Stephen hurt his arm dirt biking.
This argument makes it a strong and valid argument as there's no possible way for the premises to be true and the conclusion to be false. It's also a strong argument as being as specific as possible rules out pretty much all of the ways the premises can be true and the conclusion can be false.
Hi,
ReplyDeleteI really like the way you explained the concepts of an argument. Your examples are clear and straightforward so its easy to get. I am amused how you came up with an argument that is both strong and valid. In my opinion it’s hard to make or find an argument that like that sometimes. The special note you made was also helpful because I didn’t really know that an argument is good as long as it pass one of the tests; I thought that it needs to pass two of the three tests at least. I enjoy reading this, it was well describe and helpful.