Can an historian be truly objective?
There is a strand of fashionable postmodern thought that argues it is impossible for the historian to merely be an objective chronicler of the past. The historian is bound by his context, his judgement of past events is stained because he is looking into the past through the prism of his present value-system. It is impossible for him to detract from this context.
Not to mention that he is also a prisoner of language. Any comment he makes, beyond that a certain event happened on a certain date, is a comment that is burdened by his choice of words. Language creates reality, not facts. And language is infinitely diffuse, so infinite truths about the past can be created.
That is, history is nothing more than a fiction (see Foucalt, Hayden White, Derrida).
But the denial of a true history plays into the hands of those with vested interests in a denial of their own—eg the Holocaust never happened. Relativism legitimises Holocaust deniers and savages those who oppose them to appeal to the ‘truth.’
Objectivity is, I think, the awareness of the difficulties of being objective. If you take these difficulties into account, then something at least achieving objectivity is possible. The historian needs to be aware of such things as his own biases creeping into the construction of text and the subjectivity of primary sources themselves. While it is true, I think, that the past can only be recreated in the mind, it is possible for the shape of the past to not be a product of the mind, but rather a product of sources and source evaluation.