Christians try to harmonize apparent contradictions in Scripture given their presumption that Scripture is inerrant. To unbelievers, this is special pleading. Of course, unbelievers resist harmonization given their presumption that Scripture is errant. So the bias cuts both ways. If harmonizing Scripture is an exercise in special pleading, then, by the same token, refusal to harmonize Scripture is special pleading.
I’d add that harmonizing discrepant accounts is hardly confined to Scripture. It’s quite easy to come up with examples of apparent contradictions outside Scripture. In fact, these are ultimately harmonious, yet their consistency depends on some key piece of evidence. What is more, the key piece of evidence may not be self-evident. And, in many cases, it may not be available.
For example, I recently saw an episode of a nature show called River Monsters:
In this episode, a racehorse was attacked by some sort of aquatic creature. The culprit obviously had to be fairly formidable to pose a threat to an animal the size of a horse.
One theory is that a crocodile attacked the horse. A crocodile would be big enough to take on a horse. However, there were some problems with that explanation. Crocodiles didn’t frequent that part of the river. The bite marks didn’t match a crocodile bite. And an eyewitness said the creature appeared to be a shark.
So another candidate was the bull shark, since bull sharks can swim in fresh water, and have–indeed–been found far upriver in certain parts of the world.
However, there was a problem with that theory as well. The river had a dam downstream. A shark would be unable to ford a dam.
Suppose this is the only information we had. Suppose an eyewitness said he saw a shark attack the horse. Someone would then point out that this must be a mistaken since there was a dam downstream which posed an impenetrable barrier to a shark swimming further upstream.
This, would, in turn be cited as yet another example of how unreliable eyewitness evidence tends to be.
But that’s not the end of the story. As it turns out, the area was flooded several years earlier. The floodwaters crested above the dam, making it possible for bull sharks to ford the dam.
One of the locals was able to explain that to the host. So that threw suspicion back onto a bull shark as the culprit.
That explanation hadn’t occurred to the host. You’d have to be a local yokel to know that. It was part of the oral tradition of that particular region. Not something that’s necessarily written down for posterity.
Of course, nowadays there are local newspapers or news stations which keep records of such events. But in the past there might be no permanent record. The key piece of information would die with contemporaries.