We live in a world where arguments and debates are a part of everyday life. Not all arguments are good, or valid for that matter. Luckily for us, we have three simple tests that we can use to rate an arguments potential to be good or bad, and valid or invalid.
Here is an argument I recently heard about in another class:
An infant was recently given a vaccination shot. Soon after, the infant was diagnosed with autism. The vaccination was the cause of autism in the infant.
First, are the premises plausible? Infants are often given vaccination shots, so thats plausible. Infants can also be diagnosed with autism, so thats another plausible.
Second, are the premises more plausible than the conclusion? In this case, the premises are more plausible than the conclusion stemming from the fact that the conclusion is false. The symptoms of autism usually coincide with the time the vaccinations are given, which sadly causes people to establish in their minds that they are related, when in reality they are not.
Third, is the argument valid or strong? This argument is invalid because the premises are true, but the conclusion is false at the same time. It is a weak, and therefore bad argument because many things can contribute to an infant developing autism, often times it involves genetics. It just so happens that vaccination shots and autism symptoms occur at roughly the same time, which leads many people to create a causation effect between the two.
After reading your post I understood the concept of strong vs. weak and valid vs. invalid. You were able to give good examples that make why the argument was invalid clear. It could be confused by the way it was said that the shot caused the autism. It doesn't clearly state that it is not possible that the shot could cause the infant to get autism. If the statement was phrased, "The infant was diagnosed with autism after it was given the shot, but the disease is not a result of the shot."
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