This division is pure, grade ‘A’, nonsensical horseshit. There is no such division in science between observational and historical, there’s just science. ‘History’, a humanities subject, is sometimes called ‘Historical Science’ but in your actual ray-packs and jet-guns science, such a distinction does not exist.
Essentially, what Ken Ham is suggesting by making this division is that ‘If you didn’t see it, it didn’t happen’. Nye dealt with this quite adroitly with comparisons to procedural crime dramas like CSI and so on. Hopefully a point aimed at a level that could get through to the creationist audience. After all, everyone can appreciate the need for a justice system and one that – hopefully – catches the right guy and can prove it in court. There are many imperfect parallels between criminal investigation and science and that makes it a great way to reach people and help them understand. (Presumption of innocence = Burden of Proof, Judge & Jury = Peer Review, Evidence = Observations & Experiments).
Can we use observations in the present to determine what happened in the past?
Let us suppose that I have a piece of ham. Not Ham, just ham. Now we all know that ham is a pork product, made from pigs. Do we though? How do we know? Were we there when the ham was made? No, we weren’t. How might we use observations in the present, to determine that this ham was a pig in the past?
Well, ham is still pig flesh. We could take a biopsy from my sandwich and send it away for testing. It could then be cross-checked against the pig genome and if the genetic blueprints match any reasonable person might agree that yes, this ham used to be a pig.
We could also trace the ham back to its source. Tracking where food comes from is hugely important for hygiene and other reasons. It allowed all those ‘horsey’ lasagne ready meals to be tracked back to their source and allowed prosecutions and fines to be levelled. Incidentally it was genetic testing (see above) that demonstrated the presence of pony flesh in the first place. We can go back to the supermarket, from there to the supplier, the factory, the farm and to the herd of pigs. Depending on the country and level of food paranoia we might even be able to trace it all the way back to an individually recorded pig.
Does this not seem a reasonable way to pursue information about the past?
Ham relies on ‘testimony’, witness statements. Of course, the Bible isn’t reliable witness statements and doesn’t come from the time of the alleged events so it fails even by his own standard, but that’s another argument. Never mind that witness statements are the most unreliable form of evidence we have, they’re great at convincing juries and in a similar way ‘testimonials’ are great for convincing people to sign up to the faith and drink the Flavor-Aid. This is where science has a bit of a PR problem. Scientists rightly couch everything they say in cautious terms, but that reads as weakness or uncertainty to that kind of crowd. ‘We think’ and ‘The evidence suggests’ and ‘It’s probable that’ sounds unimpressive next to ‘I know’ or ‘God told me’, whatever the truth of the matter might be.
If we went by Ham’s way of thinking criminals would walk free most of the time and we would cut ourselves off from some of the only meaningful ways we truly have to look into the past. It is telling when someone is so utterly desperate to maintain their outmoded belief system that they’re willing to throw any and all reason under the bus.