Historians generally try to avoid making outright moral judgments about whatever they're writing about, but sometimes it can hard to avoid when talking about subjects like slavery, genocide, war, or things or figures that the historians likes.

IMO historians can make moral judgments, but first they must understand the values and social conventions of the era and judge according to those values. So it would be wrong for me to look at a medieval Irish king who owned slaves, waged wars and killed people and call them a monster because those actions are abhorrent to my personal values; slavery, war and battle were socially accepted institutions in that time period. Making such a moral judgment compromises the objectivity of your writing and opens it up to full on bias because I am projecting my beliefs onto the past.

Now let's consider what makes acceptable moral judgments. If we can't judge the past on values that were socially accepted, we can make judgments on people or things that were abhorred by their contemporaries. It would not be controversial to call Adolf Hitler a monster (and many excellent historians like Ian Kershaw regularly do) because many people in Germany and abroad thought the same thing. This is bias, but it's based in the experiences and opinions of contemporary individuals and societies. This requires researching attitudes and opinions, and leads to less bias than straight up judging stuff just because you personally don't like it. If I were to find evidence that suggested widespread opposition to slavery and war in early Ireland, then I could use that evidence to critique the practices of the social and economic elites, but the fact remains that those things were integral to Irish society and embraced by the population, and calling them bad people for thinking that way without corroboration would be biased and bad history.

Most historians tend to avoid making outright moral judgements (although they generally end up doing so anyway, in more subtle ways), but there's actually an entire field in history that exists just to make some sort of moral judgement - and that is the field of transitional justice. While it's not exclusive to historians, it's rare to find an instance of transitional justice without a historian being involved. Transitional justice is - to quote the International Centre for Transitional Justice - 'the set of judicial and non-judicial measures that have been implemented by different countries in order to redress the legacies of massive human rights abuses. These measures include criminal prosecutions, truth commissions, reparations programs, and various kinds of institutional reforms.'

The name refers to its original purpose - bringing justice when a country transitions from one regime to the next. Notable examples include Germany (once after WW2 and once after the reunification), Spain (after Franco), Argentina (after the dictatorship), South Africa (after Apartheid), and so on. The term encompasses a lot more, though, covering all situations where peace must be made with the past. It now also includes the genocides, massacres, major shifts in policy etc.

As was said in the definition by the ICTJ, this mostly comes down to criminal prosecutions, truth commissions, reparation programs and reforms. Now, to come clean with the past, one must first know the past. That's where historians come in. Truth commissions usually include mainly historians, for instance. A notable example that I know of is the Belgian truth commission regarding the assassination of Patrice Lumumba. Historians commissioned by the Belgian government came to the conclusion that Belgium was culpable in the death of Lumumba and an official apology followed soon after.

But in other cases, they'll take on an even more hands on approach. Spain, for instance, is covered with mass graves dating back to the civil war and to the Franco era. Most of these graves are of Republican forces and during the Franco era any archaeologist who tried to uncover any of these graves was going to run into some serious problems. This actually continued even after the fall of Franco, with - mainly conservatives and Francoists - opposing any attempt to dig up - literally - the past. Spain didn't want to confront their history, the policy was to just let things lie. But a policy like this never holds out - too many people were left in doubt about the fate of their families, too many problems could be traced back to Francoist days. Eventually, a grass roots movement of archaeologists and family members of those killed started unauthorised digs. Only in 2007 did the Spanish government finally agree to give their past a place and a map with over 2000 mass graves and database of victims was released. You can find it here.

In Argentina and several other Latin American countries, historians are still working with survivors of the dictatorships there (most notably with the Madres in Argentina) to uncover the truth about the past. In South Africa, they assisted the truth and reconciliation commissions.

All of this involves making explicit moral judgements (aside from any legal judgements). I myself wrote my Bachelor's thesis as a review of the Kahan Commission about the Sabra and Shatila Massacre - another aspect of the field is double checking existing truth commissions. I made some clear moral judgements there and I can't say I felt any less professional than before I made them.

I tend to take a middle path. On the one hand, taking a primarily moral approach to the past can just come off as morally masturbatory presentism - e.g, congratulating ourselves on no longer thinking slavery should be legal or that women shouldn't vote. On the other hand, a totally morally relativist approach to the past can be just as blind - there have been some truly awful things done in history, and attempting to ignore their moral dimension is to ignore a major aspect of these events.

I guess this is probably everyone's approach, but we all draw the line in different places.

Just a note that I'm removing the orange meta flair, because that's reserved for subreddit navel-gazing. However, questions about the craft of history are totaly welcome here!

I don't think judgement is useful. It helps that those I might judge have all been corpses for a few thousand years; cultivates a certain distance.

But I mean, some Assyrian kings hung decapitated heads in their gardens and ate lunch out there. What good is it to condemn something like that? Ashurbanipal wasn't a bad guy; he was a scholar and a powerful king, well regarded by his people and beneficial to their land.

I'm not condoning beheading your enemies, mind - my point is that someone can only be judged "good" or "bad" within the context that created their behavior, and it's not useful to impose any modern sensibilities on the past. We should learn from it, rather than make judgements about it. Value judgements can only cloud assessment.