10.6: Suppressed (or Neglected) Evidence

We commit the fallacy of suppressed or neglected evidence when we fail to consider (or simply overlook) evidence that is likely to be relevant to an argument. In this case, we may include premises that are relevant, but we commit a fallacy because we leave out other information that is also relevant. Of course, we cannot look at all the evidence that might conceivably be relevant (that would be an endless task). But we should never neglect evidence that we know about or evidence that seems quite likely to bear on the issue.

The fallacy of suppressed (or neglected) evidence is a generic, catch-all label. So even where none of the names of fallacies we have learned seems quite appropriate, remember that we need to consider as much of the relevant evidence as we can when we evaluate an argument.

One of the easiest ways to make our position look good and to make alternative positions look weak is to suppress evidence that tells against our view, as well as evidence that supports the alternative. So, it is not surprising that relevant evidence is constantly suppressed in partisan disputes. In the courtroom, lawyers only present evidence that will make their own case look good. In advertisements, only one side of the picture is presented. In political debates, candidates almost always present only one side of the issue. In discussions about public policy, the partisans on each side of the issue often cite only those statistics that support their side of the case. In churches, you don’t hear a lot of discussion about children dying from disease and poverty.

In many cases, it would be expecting too much to think that those engaged in intense debates over such matters would present both sides of the issue in a fair and even-handed way. But there is often a big difference between winning an argument and thinking clearly, and if we must make up our own minds on the matter (as we must when we serve on a jury or vote in an election), we must consider as much of the evidence on each side of the issue as we can. And (as we noted when discussing the strawman fallacy), we cannot rely on the critics of a view to state it fairly, especially when the point at issue is highly controversial or arouses intense emotions.

Remember not to simply invoke the fallacy of suppressed (or neglected) evidence each time you see an argument that overlooks something that seems likely to be relevant. If the argument commits one of the fallacies we have studied, it is important to note that fact. And it is even more important to explain in some detail why the argument is weak. We will study this fallacy in greater detail in a later chapter on sampling.