Presentism is viewed to be a historiographical error, and the rules of this subreddit suggest be wary of it.
Specifically with regard to moral presentism, however, it doesn't seem to be very clearly defined. Ok, so historians shouldn't hold past events and peoples to modern moral standard. Makes sense, but it leaves at least one major question open: to whose moral standards should they be held?
I was fairly taken aback by this post, which I encountered while trawling this subreddit for previous discussions of this topic. Specifically, this part:
Yes, what Columbus did to the Indians was terrible to us, but to really measure his worth you have to ask, "Was he a bad person by the standards of his time?" You can't really apply modern concepts to past events. Slavery in many parts of the world was morally justified in it's era. Yes, it's reprehensible to us now, but in the 16th Century it really wasn't. It's not fair to criticise someone using the morality of John Locke when they lived 200 years before Locke.
The implication seems to be that Locke invented the concept of abolitionism. But this makes no sense. Didn't the Tainos always oppose Columbus' and the Spaniards' rapacious genocidal behavior? Didn't the slaves of the New World always oppose slavery? Why shouldn't we hold Columbus to the moral standards of the Indians he butchered, or slavers to the moral standards of the enslaved?
The argument behind moral presentism is that we should reject using the moral framework of today. But why does that imply we should necessarily use the moral framework of Columbus? In my experience people who accuse others of "moral presentism" inevitably set up a false duality in which we pick one or the other.
So, which moral standard should/do historians use? And what's the logical reasoning behind picking that specific standard?
Further, isn't the very notion that "presentism is undesirable" presentist? It seems to be invoking moral relativism, but moral relativism itself is a pretty modern construction, no?
Both this – terrible – 5 year old post and your definition of presentism is not exactly what is generally meant by presentism when discussed among historians. Rather, the focus on moral standards is a sort of "vulgar presentism" that is popular on reddit as a concept because it is often employed as an argument against pointing out the horrible deeds of historical figures (as is the case with the poster you linked).
Presentism when discussed in historical circles is often discussed as an epistemological and methodical problem, meaning in its relation to how we gain knowledge about and insight in the past. Because presentism does not solely and not even primarily relate to moral standards but to a broader sense of ideas and concepts that we today understand as self-evident and obvious but the historical actors of times past might not.
The classical example of this is homosexual identity, which describes not the sexual behavior of same sex attraction but the gender and social performance of it. Robert Beachy in his seminal study on the subject Gay Berlin has shown how modern homosexual identity, including the ideas that same-sex sexual and romantic behavior is fundamentally different from what we describe as heterosexual behavior, that heterosexuality is the default, the ideas of sexuality being an inborn behavior occurring naturally and existing on a certain scale, the very terms to describe that, and a homosexual cultural sub-culture is something that was established and formed in 19th and early 20th century and has ever since influenced modern 20th and 21st century perceptions and cultural attitudes concerning homosexuality.
The relevance of this in the context of presentism is that while there is ample evidence that sexual and romantic behavior between same-sex partners has existed since the dawn of humanity but its understanding as being dichotomically opposed to the sexual and romantic behavior between different-sex partners is something that is a new phenomenon. Ancient Greeks and Romans were very familiar with same sex romantic and sexual emotions and practices but understood, categorized, and described them differently than we do today.
A presentist reading now would include the projection of our conceptualization of homosexuality on the ancient Greeks and Romans when they would be neither familiar with the term nor with the underlying social concept. And this represents a problem in as far as if we impose our conceptualization on the past, we do not gain insight and knowledge into the historical conceptualization, which might prevent us from gaining insight in historical societies and into the general understanding of ancient sexuality and gender.
A similar example of presentism presenting a problem is the the frequent projection of modern conceptualizations of race onto the past beyond the point they were formulated at. I have written a Monday methods about this recently where there is a lot of discussion in the comments pertaining to the issue that the question of the "race" of ancient peoples is a futile exercise in that "race" as a concept is one born from modern colonialism that ancient peoples perceived and handled different, most notably without the slew of context (and baggage) we have for it today. Hence applying it to ancient peoples is not a useful exercise because rather than allowing us greater insight into how questions of otherness were understood by them, it forces a later understanding upon a past in which said understanding didn't exist.
There are countless more examples but this should capture the gist of what historians discuss when they discuss presentism: Understanding that our concept of certain things in the world like race and sexuality fundamentally differs from that of historical actors and that when engaging in an effort to understand historical actors' actions and decisions it might not be sensible to apply them one on one.
The issue of "moral presentism" is one I have seen almost exclusively come up in reddit discussions, mostly as a cudgel to employed in the context of political discussions. In my field, the study of Nazism and the Holocaust, a long-held maxime is that to seek to understand is not equivalent with seeking to excuse. Meaning that for historians to try to understand why perpetrators of the Holocaust became perpetrators of the Holocaust, to find their motives and explanations for their actions by engaging what they wrote, said, and thought is not to morally excuse their actions. The same holds true with Columbus: An investigation of what his exact moral framework was – and I'm convinced that OP in the 5 year old thread you linked is pretty wrong in his assessment – is not a quest to exonerate, especially when it comes to the issue of how historical figures should be revered/remembered today (for more on this see our thread on confederate monuments) but a quest to try to gain deeper insight into why Columbus and the Spaniards did what they did.
Against the protestations of people like the OP in the thread you linked, historians also do and should make judgements because all writing of history is necessarily political and always relates to contemporary society and times. To use the most obvious example: The study of Nazism and the Holocaust and trying to find an explanation for why perpetrators became perpetrators is not so much an end in itself but something immediately relevant in terms of a better understanding how regimes and people turn murderous on a grand scale and thus immediately relevant to contemporary political and moral considerations. Similarly, we might understand why Columbus and the Spaniards acted the way they did from engaging with their motives and logic but this does emphatically not translate into saying that Columbus needs to be revered and celebrated figure – because the carnage he wrought is on a staggering scale.
But these issues have little to do with the problem of presentism on an epistemological level but rather with a question of engagement with contemporary society and politics.
"The argument behind moral presentism is that we should reject using the moral framework of today."
Won't happen or rather can't happen. I feel like this a problem with subjectivity in historiography: If the constructivistic premise is that any historiography is coloured by the time, and more precisely the writer her/himself, then presentism is a trivial thing which ALWAYS happens. The Writers intentional use of certain sources, his standpoint and even the language he uses (even if its not tendencially language but just the difference between english and german) excludes him from a loci observandi. Therefore he uses Qcriteria, but still cannot avoid being somehow subjective.
So my point is: Just make it transparent that this judgement might be influenced by certain (moral) circumstances of the present. In Germany we just call it "Sachurteil" that tries to judge within the timezone and a "Werturteil" that judges based on our current moral standards.