This is a constant issue with things like moneyed interests, lobbyists, 24 hour news networks, the internet, hearsay and in current affairs; election polls.

Who's numbers are we to believe? Who's viewpoints are we to accept?

It's a tough call especially considering the 24 hour news cycles and misinformation and even intentionally disinformation.

The best way to tackle these things is first to verify the credentials of the source and see if it seems reliable. Next, verify that the information seems pragmatically appropriate and apply Occam's Razor. After that scan for logical fallacies. The final point is the most subjective, which is align yourself with news outlets that you find to be more trustworthy and representative of quality data.

At the end of the day even the most trusted news source could end up being verifiably wrong, but by taking a pragmatic, hard-science approach to the issues we value and the news we receive we can help minimize the frequency that our trusted news outlets are incorrect.

For a more interactive person you can also do more fact checking, but even then fact checking is interpretive as well. For example, I love politifact, but their conclusions are still based in interpretation of data rather than the raw data itself, even though they are really good about it.

How do I consider information to lack validity?... Well logical fallacies present in an argument are usually red flags, but we can't assume the data is wrong just because of a fallacy, for that would create a logical fallacy in itself. Next is to compare it to data and experiences I have as either expert or greater knowledge and also understand that anecdotal data is not viable grounds for scientific conclusion, though it can often help me spot weaker bits of information/arguments.

Another tactic I take is to look at several sources as the internet is never short on opinions and interpretations for pretty much anything, especially buzz words of the modern day. By comparing and contrasting several different viewpoints I am able to establish a much broader understanding of a topic and understand that often the truth of a matter is rarely at one extreme or another, but is usually a little bit of columns A, B, and C. Using this method helps one avoid tinfoil-hat syndrome, where they follow what appears to be a series of logical conclusions if outside evidence is ignored, and end up somewhere far over the line of ridiculous conspiracy theory (so named for individuals who wear tinfoil hats to prevent aliens from reading their brain waves).

With a good foundation in logic and an understanding of the scientific method we can often remove ourselves from how we "feel" and taking that as truth (feelings are frequently easily manipulated), and move more in the direction of what objectively "is".

Getting more into the existential ramifications we can't ever meaningfully know anything for certain due to "brain in the vat" issues, Hume's Fork and Schroedinger's cat, but we can understand "the being in itself" and that such arguments rely heavily on very shakey, and more importantly, spurious definitions of knowledge and meaning and we may take comfort in the fact that such conversations are hardly urbane.