Let me ask you a simple question. Do you consider it possible, for example, that a new discovery in the fossil record could reveal that snakes actually evolved from different ancestors? The pylogenetic tree undergoes changes on a regular basis and it wouldn’t be the first time that science had to amend a hypothesis to recognize previously unknown information.
Of course it's possible. The question is not whether something's possible - meaning that you can quantify the chances of it happening as greater than 0%, no matter how minutely - but whether it's likely - meaning that the chances of it happening are meaningful. For example, take a person being hit by a meteorite. According to National Geographic
, there is only one person in human history who's been confirmed to have been hit by a meteorite. As Michael Reynolds, an astronomer cited in that article, says, "You have a better chance of getting hit by a tornado and a bolt of lightning and a hurricane all at the same time."
So the question is not whether it's possible that someone might find evidence in the fossil record that shows that snakes evolved from a different ancestor, but just how likely it is that someone will. However, that's not the reason you're bringing this up. You're bringing it up so you can 'prove' that science textbooks are inaccurate, even though what you're referring to is pure semantics. Your whole point was that the textbook said that scientists knew something was true, and to cast doubt on whether they knew it for sure. That kind of anal retentive nitpicking doesn't really accomplish anything.
I could insert jaimehlers where Biblestudent appears in your comment and be just as suspicious of your bias.
No, you couldn't. You know why? Because there's a key difference between you and I. You are not expressing this skepticism out of a genuine desire to improve science, at least as far as I can tell. You are doing it so you can avoid having to seriously acknowledge that your beliefs - based on an ancient holy book written by people who knew a tiny fraction of what we know today - might not be correct. I wouldn't be surprised if you gave lip service to that, but I don't think you've given it any real consideration. In short, you're only interested in pointing out possible flaws so you can maintain the Biblical beliefs you were taught as a child with as little change as possible. You have a vested interest in those Biblical beliefs being correct.
When I read something in science, I keep in mind that it's just the latest word. Experiments or evidence next year, or next century, might show it to be wrong. But until someone actually does show it to be wrong, there is no point in assuming it is. That's why trying to insinuate that I'm just as biased as you isn't going to work - because I don't have a vested interest in a specific factoid of science being right. Say someone were to find evidence that snakes weren't actually descended from lizards, sometime in the future. If that happens, then as long as the evidence supports it, I'm okay with it. It doesn't make the scientific process wrong, it just shows that we improved our knowledge.
For that matter, if someone were to come up with real evidence that showed that something came and tinkered with life on Earth in the past, designing it in some way, then as long as they have evidence, I'm okay with it. But without the evidence, any such claim is nothing but speculation. That's where intelligent design falls short and where it will continue to fall short - because it has no actual evidence of an intelligent designer. We can't base knowledge on things that people would like to be true, or think might be true, or think might not be true - we have to stick to what the evidence actually shows is true. So when we find additional evidence, we have to fit that in - and if it means coming up with new theories, so be it.
Before you respond, consider how actual genetic engineers work. They take organisms that have desired traits and use something, usually tailored viruses, to transplant the gene for that trait into another, completely unrelated organism. More to the point, it isn't a gradual change that occurs over hundreds or thousands of generations, the way evolution works. That's the kind of thing I'd expect to see from an intelligent designer - making significant changes over a very short period of time (from one generation to the next), and continuing to make changes as needed over subsequent generations, as well as acting to conserve those changes so that subsequent generations aren't likely to wipe them out. Yet in our own fossil history, we see nothing like that. Instead, we see exactly what we'd expect of natural selection as predicted by evolution.