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Non sequitur
(Latin: "it doesn't follow")

As a writer, you want to ensure that your readers will follow your arguments easily and find them convincing. To build sound arguments, you need to be aware of common errors (or fallacies) in logic and be careful to avoid them. There are many types of logical fallacies. In this article, we'll look at non sequitur errors.

In this error in logic, the writer makes a statement that doesn't follow logically from the one before it. Usually the two thoughts are connected, but the writer has left out key steps in the reasoning process because he or she thinks they are obvious. Remember: what is obvious to the writer isn't always obvious to the reader!

Nearby farms stockpiled manure. Therefore, authorities should have told residents not to drink the water.

The connection between the first statement and the conclusion is not clear. The writer needs to explain the connecting steps: E. coli leached from the manure into the water system. The wells then became contaminated, so the municipal water wasn't safe to drink.

John approved the funding before the committee meeting, so we will have to cancel the project.

A logical connection does not exist between these two statements: If the funding was approved, it does not make sense to cancel the project. Again, the writer needs to explain what happened between the two events: at the meeting, the committee overruled John's decision. With the phrase "before the committee meeting," the writer is suggesting that something happened at the meeting to reverse the decision, but it is important to state facts clearly rather than simply to imply them. Don't make your reader guess what you mean!