1.5: Using Your Own Paraphrases of Premises and Conclusions to Reconstruct Arguments in Standard Form

Although sometimes we can just lift the premises and conclusion verbatim from the argument, we cannot always do this. Paraphrases of premises or conclusions are sometimes needed in order to make the standard form argument as clear as possible. A paraphrase is the use of different words to capture the same idea in a clearer way. There will always be multiple ways of paraphrasing premises and conclusions and this means that there will never be just one way of putting an argument into standard form. In order to paraphrase well, you will have to rely on your understanding of English to come up with what you think is the best way of capturing the essence of the argument. Again, typically there is no single right way to do this, although there are certainly better and worse ways of doing it. For example, consider the following argument:

Just because Jeremy’s prints were on the gun that killed Tim and the gun was registered to Jeremy, it doesn’t follow that Jeremy killed Tim since Jeremy’s prints would certainly be on his own gun and someone else could have stolen Jeremy’s gun and used it to kill Tim.

What is the conclusion of this argument? (Think about it before reading on.) Here is one way of paraphrasing the conclusion:

The fact that Jeremy’s prints were on the gun that killed Tim and the gun was registered to Jeremy doesn’t mean that Jeremy killed Tim.

This statement seems to capture the essence of the main conclusion in the above argument. The premises of the argument would be:

1. Jeremy’s prints would be expected to be on a gun that was registered to him
2. Someone could have stolen Jeremy’s gun and then used it to kill Tim

Notice that while I have paraphrased the first premise, I have left the second premise almost exactly as it appeared in the original paragraph. As I’ve said, paraphrases are needed in order to try to make the standard form argument as clear as possible and this is what I’ve tried to do in capturing premise 1 as well as the conclusion of this argument. So here is the reconstructed argument in standard form:

1. Jeremy’s prints would be expected to be on a gun that was registered to him
2. Someone could have stolen Jeremy’s gun and then used it to kill Tim
3. Therefore, the fact that Jeremy’s prints were on the gun that killed Tim and the gun was registered to Jeremy doesn’t mean that Jeremy killed Tim. (from 1-2)

However, as I have just noted, there is more than one way of paraphrasing the premises and conclusion of the argument. To illustrate this, I will give a second way that one could accurately capture this argument in standard form. Here is another way of expressing the conclusion:

We do not know that Jeremy killed Tim.

That is clearly what the above argument is trying to ultimately establish and it is a much simpler (in some ways) conclusion than my first way of paraphrasing the conclusion. However, it also takes more liberties in interpreting the argument than my original paraphrase. For example, in the original argument there is no occurrence of the word “know.” That is something that I am introducing in my own paraphrase. That is a totally legitimate thing to do, as long as introducing new terminology helps us to clearly express the essence of the premise or conclusion that we’re trying to paraphrase.¹ Since my second paraphrase of the conclusion differs from my first paraphrase, you can expect that my premises will differ also. So how shall I paraphrase the premises that support this conclusion? Here is another way of paraphrasing the premises and putting the argument into standard form:

1. Tim was killed by a gun that was registered to Jeremy and had Jeremy’s prints on it.
2. It is possible that Jeremy’s gun was stolen from him.
3. If Jeremy’s gun was stolen from him, then Jeremy could not have killed Tim.
4. Therefore, we do not know that Jeremy killed Tim. (from 1-3)

Notice that this standard form argument has more premises than my first reconstruction of the standard form argument (which consisted of only three statements). I have taken quite a few liberties in interpreting and paraphrasing this argument, but what I have tried to do is to get down to the most essential logic of the original argument. The paraphrases of the premises I have used are quite different from the wording that occurs in the original paragraph. I have introduced phrases such as “it is possible that” as well as conditional statements (if...then statements), such as premise 3. Nonetheless, this reconstruction seems to get at the essence of the logic of the original argument. As long as your paraphrases help you to do that, they are good paraphrases. Being able to reconstruct arguments like this takes many years of practice in order to do it well, and much of the material that we will learn later in the text will help you to better understand how to capture an argument in standard form, but for now it is important to recognize that there is never only one way of correctly capturing the standard form of an argument. And the reason for this is that there are multiple, equally good, ways of paraphrasing the premises and conclusion of an argument.

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1 How do we know that a paraphrase is accurate? Unfortunately, there is no simple way to answer this question. The only answer is that you must rely on your mastery and understanding of English in order to determine for yourself whether the paraphrase is a good one or not. This is one of those kinds of skills that is difficult to teach, apart from just improving one’s mastery of the English language.