A favorite tactic of creationists is to ask the question, “How do you know (about dinosaurs, mountain building, the Grand Canyon, or any fact you bring up)? You weren’t there.” Ken Hamm in particular likes to use this strategy, and he teaches it to kids all over the country. Those who bring this query up to their teachers have a smugness about them as if this question settles the argument in their favor for ever and for always. It doesn’t, of course, but it is a question that deserves closer examination. For starters, it’s a great science question. The proper scientific response to any claim is, “How do you know? What’s the evidence?” Secondly, the question is a two-edged sword. How do creationists know God wrote the bible? They weren’t there. Biblical literalists want to argue that their beliefs are no different than those of a scientist. They want to convince people that all assumptions are equally valid. But the assertion of equality of assumptions is easily disproved. Exhibit A comes from Vanessa Wamsley, who wrote about the question in a Slate article. She is now a science writer and seems somewhat embarrassed by her use of the question when she was in high school biology class. As she describes it, her teacher gently explained that he wasn’t out to change her beliefs, just present the scientific evidence. And over time, the evidence won out.
Ms. Wamsley is lucky I wasn’t her science teacher. I refuse to let my students off of the hook when it comes to the logical conclusions that follow their beliefs. When students ask me this question, I immediately go to sex. His or her parents had sex and he or she is the result. Then I ask, “How do I know this? I weren’t there.” This is an assumption on my part. A pretty good one, I might add. Sure we could bring artificial insemination or test tube babies into the equation if we are talking about the last 50 years. These are remote possibilities. But even in those rare cases, two gametes had to merge to create a new human being. Which is the purpose of sex in the first place. Now what about the parents of that person? Did their grandparents have sex? How do I know? I wasn’t there. What about their great grandparents? And their great-great-grandparents? How far back into human history does the assumption remain valid? For a scientist, the assumption is always valid. Humans make new humans through sexual activity. We may not like to think about our parents and grandparents having sex, but that’s how life works.
Compare this assumption with the creationists’. They say Adam was fashioned out of clay and Eve out of his rib. They believe that Jesus was a miracle. No sex involved. How do they know these things to be true? They weren’t there. Their answer is that God said it, and they believe it. Of course they weren’t there when God said it either, but all facts that are contrary to their beliefs are “tests of their faith.” They espouse the belief that God creates life through processes we don’t understand. And I call BS on that argument. We do know how life is created. Life begets life. Either sexually or asexually. Either way, DNA and RNA are involved, and we know the exact chemical language used in reproduction. That is the sum total of our observations, and it is the fundamental principle of evolution. If you expect me to accept a different story, show me the evidence.
The fact that there is no reproducible evidence of special creation is okay. You don’t have to change your belief system. Anyone is free to believe whatever they want to believe. But these contrasting assumptions about how humans come into existence, cell division vs. miracles, are not of equal validity. Science assumes the laws of nature are constant. That’s why we wear seatbelts and condoms. Creationists assume God suspends the laws of nature whenever she feels like it. Who needs seatbelts when God can save you? Who needs condoms when God will decide if you will have a baby?
So if you ever find yourself talking to someone who asks how you know about dinosaurs, the Grand Canyon, etc., you have an answer. You know the same way you know their parents had sex. If nothing else, the mental picture will shut them up long enough for you to get away gracefully. I admit that I have gotten in trouble for this strategy. But I have never had anyone successfully dispute its truth.