I've been brooding over something somebody said during a conversation at a party before Christmas in the context of the relationship between historians and science fiction, where somebody mentioned that history is one of the humanities which involves looking at/for evidence, and I suggested that historians are interested in the factors leading to change within societies, and then somebody said
'I thought history was about assessing which was the most reliable account'
Which is, when I came to reflect upon it - party conversations not being great for pursuing intricate trains of thought - a rather naive view of What Historians Do. Even if historians do have to have a nose for the reliability of the evidence they consult.
As an archivist, of course, one of the things in which we are interested is making sure the record is an authentic record and not letting people either remove things, or insert things that compromise the integrity of the record - e.g. The 29 fakes behind a rewriting of history or the insertion into the Tate Archives of documents creating false provenance for forged artworks
But as a historian there are still issues of interpretation to the documents, and it's not necessarily that one will be 'more reliable' than another: it's more about 'what does this mean?', 'how much weight should we give to this?' and piecing together an array of different materials rather than having The One True Account.
Also, what does reliability mean? A document which is entirely unreliable in one respect may be extremely reliable in another, if only as an exemplar of the kinds of stories that were being told.
Documents and other evidence also exist within a context, and sometimes people who are focusing on these traces lose sight of the bigger picture of which they are part, and thus miss important points.
History is rather less about establishing The Real Truth and more about discussions and debate on the meaning of the evidence and how we interpret it.
Though what is history and how do we do it is pretty much an endless discussion.