Media was wrong before

The media was wrong before is the fallacious idea that if an information source is occasionally incorrect, then it is wholly untrustworthy and none of it should be taken as truth. This is not logically valid because it is possible for information sources to make a stupid mistake and still generally be correct. The only way to prove that a source is not trustworthy is to show an overwhelming pattern of mistakes. In short:

The idea is closely related to the idea that right and wrong are relative. It is a sister fallacy to science was wrong before.

Logical flaws
The "media was wrong before" idea takes the form:

When P2 is explicitly stated, it should be obvious that this idea is wrong.

Bayesian truth
No information source has ever been perfect. However, it should be obvious that some sources are better than others. For example, you probably have some family or friends or co-workers whom you trust more than others. But it's ridiculous to put all of these sources into the same box of things that are "flawed and totally worthless". As Isaac Asimov put it: [W]hen people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together.

In other words: Yes, information sources are flawed. But you shouldn't throw up your hands and deny all truth. Instead, accept that truth is a gradient and choose sources that get things correct more often or that are more likely to be correct. The better your sources are, the more likely you are to be correct.

Hanlon's razor
Most mistakes are probably not made maliciously. For example, CNN and other major American news networks probably didn't popularize the Bush Administration's WMD story because they wanted war; instead, it's more likely that they (like Congress) were lied to. As such, major American news networks shouldn't be seen as perfect, but instead as flawed truth-seekers. With some exceptions, of course.