This isn't a new issue created by either social media or the internet. It is an innate problem with absolute free speech and has directly led to the US entering multiple wars over the last 125 years. It doesn't matter if the lies are disseminated through newspapers, cable TV, or Twitter. Mass media is just an amplification device. That has been true for centuries. The only new aspect is that the rate of amplification is increasing which leads to the underlying issue becoming even more problematic.