What is the epistemic justification for hearsay?

Question

In the United States, Donald Trump's election has been all the rage, and his Tweets and public declarations have received much attention, especially those that accuse CNN and the "liberal media" in general for being "fake news." Prima facie, this is an attempt to refuse facts for the sake of an agenda. However, these people who cry "fake news" may be on to something; while it might seem to be easy to justify the epistemological validity of news coverage, the problem ultimately boils down to the justification of hearsay: "I asked the man in the airport where the bathroom was, and I trusted him" is of a similar form as "I saw on The Washington Post that Scaramucci made some vulgar comments about Steve Bannon, and I believed it." Here's my main question:

What is the epistemic justification for knowledge by news/hearsay? Is there a specific epistemological problem for this, and if so, what is it called?

Answer 1

Philosophically, hearsay that is meant literally - i.e., not rhetorically, playfully, figuratively, ironically, etc. - is normally referred to as testimony. Whether the testimony included in news coverage is meant to be taken literally is not clear even if it is clear that many viewers do take it literally.

I believe that David Hume's considerations of the epistemological validity of testimony is among the earliest philosophical treatments. See Of Miracles from his An Enquiry concerning Human Understanding (1748). Unsurprisingly, Hume wrote that testimony might be doubted even from some great authority in case the facts themselves are not credible.

The SEP includes an interesting article on the subject : Epistemological Problems of Testimony. The article identifies three features of testimony which indicate the wide scope of the problem of its epistemological justification. Most relevant here is :

The third feature that attests to the wide scope of the Vulnerability Problem is the typical infeasibility for hearers to seriously check or confirm either the speaker's reliability or sincerity within the normal constraints of testimonial transmission and exchange.

Answer 2

Probably "what seems reasonable", although this itself is highly subjective, as demonstrated by the great gulf between what factions in the US consider "reasonable".

There are issues with journalism to be sure. For instance, any coverage of the national debt that only mentions the size of the debt is an abuse of statistics, because the number is meaningless without the context of currency values, interest rates, percentage of GDP, etc.

Nevertheless, the purpose of Journalism, similar to science, is to report on events/phenomenon is the most objective manner possible. (True objectivity is impossible within any given system, including what we call "reality", but that does not negate the legitimacy of the goal.
Thus reasonable analysis of data and application of confidence levels in interpretations is critical.)*

Based on Mr. Mooch's own admission, it is quite reasonable to assume he used vulgarities in reference to this or that person. By contrast, one might be more skeptical of similar hearsay in regards to President Obama, because he doesn't have a track history of public profanity, but might be more open to the hearsay that someone "saw the former President sneaking a cigarette on the patio at the Country Club," because he documented as having this habit early in his presidency.

Part of the problem is that critical faculties differ with each individual, and the embracing of one's biases, which can be a tool, seems rarely tempered by questioning of one's assumptions.

The issue partly relates to the hegemony of subjectivity, which is sometimes abused to cast doubt on scientific positions. (The idea that "evolution is just a theory" demonstrates unequivocally that speaker possesses not even the most basic grasp of what science is per their misunderstanding of "theory", equated in this case with what is known as an "hypothesis".)

So, despite the addage that "Opinions are like #ssholes--everyone's got 'em", not all opinions are equally valid, because some "opinions" are supported by evidence.

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