A few weeks ago, when the Atlantic article came out saying that Donald Trump had called people in the military "losers" and "suckers", I got into it on-line with someone about evidence. They didn't approve of anonymous sources. So I posted the video of Trump calling McCain a loser and "not a war hero":
And the Howard Stern interview, where Trump called STDs his "personal Vietnam. I feel like a great and very brave soldier."
And said that I thought we could perhaps extrapolate future behavior from prior statements. Now I wouldn't have minded an argument on freedom of speech - I'm always ready to defend that one - or even the validity of judging someone by their past behavior. BUT the reply I got was that "the videos are just circumstantial evidence." So I blew a gasket. Because of course no, they're not.
In history, we call direct evidence primary sources: original things (diaries, letters, stelae, pottery, tombs, and other original artifacts of all kinds). Secondary sources are analyses or discussions about primary sources (like textbooks, pundits, op-eds, and conspiracy theories). For an historical argument to be sound, it must be supported / defended by primary sources, and must be analysis of the evidence. Yes, opinions will crop up and even barge in, but there damn well better be strong primary sources.
That does not mean there will not be debate, furious, even murderous. It also doesn't mean that point of view doesn't matter, whether from the originator or the historian. For example, in the old days, i.e., up until the 1950s, most history was about war, royalty, and nobility, with a very occasional mention of peasants. That was what was "important" to the primarily European men who wrote history. And there was also plenty of documentation - low hanging fruit you might say.
But then things changed, because historians began to study things like 100 years of church registers, noting the number of bastards born in, say, a town in Normandy. Or the court records of counties, noting how many cases of assault there were in an average year (a lot - the Middle Ages had a fairly high level of violence). Or... you get the idea. And suddenly we had social history, with histories of (for example) a village in the Pyrenees like Le Roy Ladurie's brilliant Montaillou. This was based on Inquisition documents (1294-1324 AD) where they wrote down the interrogations of peasants about the Catharist heresy in their village (and there was a lot), and along the way recorded everything from how people got their bread (and how much it cost) to who combed whose hair for lice and why.
This also changed what was seen as the impetus for change. For example, today, it's pretty much a given that the Renaissance was largely triggered by the Black Death, which (by killing a third of the world in its first 4 years - 1347-1351 - and its repeat performances every 10-20 years for the next 300 years) basically overturned much of the medieval order of peoples and ideas (including that "God's in His heaven and all's right with the world - obviously something was seriously wrong), and set the stage for not just the Renaissance but Martin Luther and the Reformation.
In the same way, Jared Diamond's 1997 Guns, Germs & Steel, challenged the traditional Western Eurocentric theory of world history by showing through primary sources (direct evidence) that the gaps in power and technology between human societies originate primarily in environmental differences and had nothing to do with the superiority of Europeans over the rest of the world. (See Wikipedia for a concise overview, but better yet, read the book yourself - fantastic.) And it in turn fed off of Alfred W. Crosby's The Columbian Exchange, which discussed the widespread transfer of plants, animals, culture, human populations, technology, diseases, and ideas between the Old and New Worlds, changing ecosystems world-wide. (Again, read the book.)
BTW - one of the great examples in literature of historical arguments (and how much analysis, deduction, argument, and debate they require) is not Dan Brown, but Tom Stoppard's 1993 play Arcadia, which deserves far more productions (and at least one movie! Please!) than it has gotten. Alternating between the mid-1800s and the present, the present scenes show dueling historians arguing over the following primary sources: mid-1800s "game books" (i.e., hunting records at a country house), a diary (by a young girl), and a number of letters and notes tucked into a poetry book which itself was heavily underlined. All of which seem to indicate that Lord Byron killed minor poet Ezra Chater in a duel over Chater's wife at this country house where they were all guests at the same time, and after which Mr. Chater disappeared, and Lord Byron fled to the Continent for two years. Solving what belonged to whom (including who did all that underlining) is a masterclass in historical deduction and detection.
Also, I would give almost anything to have seen the 1993 production: directed by Trevor Nunn with Rufus Sewell as Septimus Hodge, Felicity Kendal as Hannah Jarvis, Bill Nighy as Bernard Nightingale, Emma Fielding as Thomasina Coverly, and Harriet Walter as Lady Croom (Wikipedia).
Anyway, the point is that you can debate the meaning of various primary sources, i.e., direct evidence - what you cannot debate is that they are real and they are relevant. We have to keep people accountable for what they say and write. Especially politicians, who currently are trying to have it both ways: They mean what they say until they're in the hot seat, and then they either never said it or didn't mean it or were only joking.
We have to keep reminding people that without the clear, continuous definition of original sources / direct evidence vs. secondary sources / circumstantial evidence, we will lose more than good historical argument: we will miss justice as well. And perhaps democracy.
