Can we ever know anything about history?

In this article, Antulio Echevarria makes a very plausible argument that teaching history in military eduction is more useful in providing students with critical-thinking skills than to give them "vicarious experience" of historical events:  The Trouble with History Parameters Summer 2005.

But the first half of his article is devoted to making a case that would presumably be welcomed by postmodernists, Christian Right flat-earthers and people who want to rewrite history in bizarre ways.  He essentially argues that we can't really know anything about history.  He rehashes the argument several different ways.  But the following contains his main concept:

The fundamental problem for historians is that, aside from being able to refer to such demonstrable facts as do exist, they have no objective references for determining (beyond a reasonable doubt) to what extent the histories they write either capture or deviate from the past. Put differently, they have nothing resembling the scientific method to aid them in determining whether what they have written is somewhat right, mostly right, or altogether wrong about the past. Quantitative history, intellectual history, “history from below,” and oral history, for example, each employ different methods. Yet none of those procedures can lay claim to the reliability of the scientific method—that is, developing a question or a hypothesis, conducting experiments to test it, revising the original hypothesis, then conducting further experiments to confirm the revised hypothesis, and finally reaching a conclusion.

Although historians may begin their research with a question or hypothesis, they cannot conduct the various experiments necessary to determine whether the main conclusions they have drawn about what happened are in fact valid. They cannot duplicate Pickett’s charge at the battle of Gettysburg with all the variables exactly as they were, for instance, and then change a few of them to determine whether the Confederate assault might have succeeded under different circumstances: earlier or later in the day, perhaps, or further to the left, or more to the right. Nor can they isolate the variables in a past event for closer study in the same way scientists—chemists, for example—can separate the key elements in a compound. Removing all the elements surrounding Pickett’s charge does not make the charge any easier to understand. In fact, without the historical context, the past is likely to remain essentially mute, unable to tell us much about itself. We might not be able to recognize Pickett’s charge itself as a charge.

Say what?  Pickett's charge may not have been a charge?  Or, it's only a charge because we think it's a charge?  So if we called it an "outing," it would be an "outing" and not a "charge"?

Yeah, I can see that this method would be useful.  Weapons of mass destruction in Iraq?  No, that wasn't the reason for war, of course not.  We wanted to liberate the poor oppressed Iraqi people.  Because the Republican Party has always been completely committed to freedom and human rights for Iraqis.  Oh, and we had to put an end to the oil-for-food program abuses.  And, shoot, those WMDs are probably buried in Syria or something, anyway.

Yes, that view of history can be used for lots of things.