A fictional dialogue exploring how we know what we know through science
Mrs. Sullivan held up a fossil trilobite, turning it slowly in the afternoon light.
“This little guy lived over 500 million years ago, and in our next chapter we’ll learn how the diversity of all life on Earth came about slowly through small modifications, generation after generation, from a single life form population that lived over 3 billion years ago.”
Immediately a student with a highly concerned look on her face shot her hand in the air, waving it around urgently.
“Jenny, did you have a question?”
“Yes, Mrs. Sullivan, my pastor has told us many times that evolution is just a theory and has never been proven.”
“I appreciate your concern, Jenny, but our certainty about the evolution of life on Earth is affirmed by over 150 years’ worth of research and evidence.”
“But was anyone actually there, Mrs. Sullivan?”
“Excuse me? I’m not sure what you mean, Jenny”
“Was anyone there 3 billion years ago? Has anyone actually seen one life form evolve into another one?”
“No, it’s not like that, Jenny…”
“Do you know how the first living thing got started from just random chemicals and rocks?”
Mrs. Sullivan started to respond, but Jenny was already shaking her head. “No, Jenny, but there is a lot of research…”
“Where did DNA come from? Can you tell me that?”
“A recent hypothesis suggests that something called RNA…”
“You don’t really know, do you Mrs. Sullivan? No one knows.” Jenny’s voice was getting more strained. “What about fossils? Why are there no fossils that are half cat and half dog? Or half fish and half reptile?”
If it weren’t for the tears and Jenny’s obvious agitation, Mrs. Sullivan would have been angry at being interrupted so many times in front of all the students. But she could see that this was very disturbing for Jenny.
“Jenny, I can see that this is very important to you, but if you have some patience, we can answer a lot of your questions in the next few weeks of lessons.”
Composing herself, Jenny then asked quietly, “Mrs. Sullivan tell me this. Has anyone actually seen evolution happening?”
“Why yes, Jenny. In one of our lessons we will talk about how a recent experiment with bacteria shows how an organism can evolve to adapt to a very new set of conditions in its environment.”
“What did the bacteria become?” Jenny asked with genuine interest.
“More bacteria, Jenny, but the new bacteria were able to thrive and multiply in a different set of nutrients where the old one could barely stay alive.”
“See, that’s what I mean Mrs. Sullivan—it was still bacteria. I know living things can adapt to new situations, but no one has actually seen one living thing turn into a very different living thing.”
“The kind of change you are talking about takes hundreds of thousands of years to hundreds of millions of years,” said Mrs. Sullivan.
“If that is true, no one can ever see it happening. No one can test it or repeat it with experiments like you taught us at the beginning of the year. Scientists must be just taking this all on faith, like believing in God.” Jenny stopped for a moment to compose herself, then said quietly before sitting down, “If no one was there to see it happening then how do we know it happened?”
The other students were staring at Mrs. Sullivan wondering what was going to happen next in this confrontation. Mrs. Sullivan stood looking at Jenny with a confused look on her face. “Jenny, since you came to our school this year, Mr. Miller said you attacked your chemistry assignments like you couldn’t get enough of them. And Mrs. Kroger told me that you already knew most of the algebra she was teaching last semester.”
“Yes, I love science, Mrs. Sullivan. It’s my favorite subject. I read every book on science my father brought home.”
“Brought home?” Mrs. Sullivan asked.
“Yes, I was home-schooled before I came here. I studied lots of science. I would love to work as a scientist, but I don’t know what field yet. So far, every field of science is interesting to me.”
Mrs. Sullivan looked thoughtful for a moment and then asked, “Jenny, why are you so doubtful about the theory of evolution? That theory is as well established as any other long-standing scientific theory. Evolution is considered the unifying principle in biology much like Newton’s Laws of Motion and Gravity were for classical physics.”
The Demonstration
“But that’s just it, Mrs. Sullivan.” Jenny stood up beside her desk. “Gravity and Evolution are not the same kind of theories.”
She picked up her heavy biology textbook, held it out in front of her and let it fall to the floor with a loud ‘Wham’.
Jenny sat down, slightly out of breath from her demonstration. “That’s what I mean by being there. I can repeat that experiment one hundred times and see the same result. That’s real science. Now can anyone show me a fish turning into a reptile?”
The Deeper Question
The class turned to Mrs. Sullivan, eager to hear what she had to say.
Mrs. Sullivan said, “Jenny, thanks for that demonstration. I agree that your experiment is scientific, but I think you missed something very important.” She turned to the class and said, “Can anyone tell me what they saw in Jenny’s experiment?”
Gail’s hand shot up. “Gail?” asked Mrs. Sullivan.
“Umm I saw Jenny let go of a book and it fell to the floor because of gravity.”
“Really? I saw the book fall to the floor too, but did you see gravity? What color was it?”
“Aw c’mon, everybody knows it’s gravity,” said Bob, “We can feel gravity. Are you trying to tell us it’s not gravity?”
“No, not at all. I am asking why are you so confident it was gravity? This is science class, and Jenny has raised a question about how we know things about nature through science. Or more specifically, she is asking how we can know things through science we cannot directly observe. Now how many of you actually saw gravity pulling the book to the floor?”
Gail raised her hand again and Mrs. Sullivan nodded. Gail said, “I saw Jenny let go of the book and it fell to the floor and made a loud noise.”
“Excellent!” said Mrs. Sullivan. “Do you think this would happen every time?”
“Yes, I have seen enough books fall to say that it is a fact,” said Gail.
“A fact! Yes, I think that you can say that. But what about gravity, Gail?”
“Umm… I am as sure about gravity as I am about books falling but I can’t tell you why I am so sure except that’s what I have been taught ever since I can remember.”
Mrs. Sullivan walked over to Jenny’s desk and asked, “Jenny, were you there when the book fell to the floor?”
“Umm, yeah, I was the one who dropped the book,” said Jenny, laughing along with the rest of the class.
“So did you actually see gravity, smell gravity, hear gravity, or feel gravity?”
“I feel gravity.”
“Ah, and what else did you experience?”
The class was quiet for a moment until Bob said, “Oh, I saw the book fall and it made a noise.” Everyone agreed.
“Who gave us the first testable theory about what causes things to fall?”
The class was silent until Mrs. Sullivan picked up an apple off her desk, gently tossing it up and down and humming a tune. Jennifer lit up right away and said, “Newton!”
“Right, Jennifer, you did a great presentation to your science class last year on Newton’s Laws. Now when did Newton reveal that theory?”
“He published it in 1687.”
“How long ago was that?”
Bob looked up from doing the math and said, “About three hundred and forty years ago.”
“Ok, three hundred and forty years ago. How long do you suppose humans have been seeing things falling?”
The class looked puzzled for a moment, but Gail raised her hand and said, “Umm, about as long ago as people could see anything and think about it. A million years? More? I don’t know.”
“That’s as good an answer as any, Gail. So why do you suppose it took so long for someone to come up with an explanation for falling?” Everyone seemed momentarily stunned. “Jenny”? Jenny shrugged her shoulders looking equally stunned.
Mrs. Sullivan broke the silence. “Ok, Jenny, come up here to the front with your book and let’s do your experiment again. Everyone, come up and gather around Jenny so we can all see it closely.” Everyone came up and gathered around Jenny. “Jenny, repeat your experiment.” Jenny held the book out at arm’s length and let go. The book dropped to the floor with a loud bang. “Ok, now let’s suppose we are in the year 1685, two years before Newton published his theory about motion and gravity. You all watched the book fall. You were all there when it happened. What is the cause of that book falling to the ground?”
Everyone was silent. They all looked at the book on the floor, looked at each other and then looked at Mrs. Sullivan. She said, “So we must be missing something. Jenny, what were you saying about some kind of distinction for different kinds of scientific theories?”
Jenny turned to the class and said, “There are two kinds of science. My pastor explained it during youth group. There’s the kind of science you can test in a lab, where you can run experiments over and over to see if you get the same results. That’s Operational Science. Like if you drop a ball or a book, you can see it fall every time and measure how fast it goes.
“But then there’s Historical Science, which is about stuff that happened a long time ago, like millions of years ago. You can’t do experiments on that because you weren’t there to see it happen. It’s more like guessing based on clues. My pastor says scientists sometimes pretend they know for sure what happened, but really, it’s just their opinion. That’s why evolution and the Big Bang don’t count as real science—because no one was there to see them happen.”
“Ok, so what is missing from our experiments with the book falling? According to the notion of Operational Science, we are actually witnessing the falling object. Why are we not able to figure out the cause of this phenomenon?” said Mrs. Sullivan.
“According to the scientific method that we learned about last year, we need a hypothesis,” said Bob. “We need to use our observations to create a hypothesis.”
“Right, but how do we create a hypothesis. All we have is one clue so far, which is that things fall to the ground when you drop them,” said Mrs. Sullivan while looking at the clock. “Ok, I see we are out of time. Let’s assume that we need more clues than just dropping a book. Who wants to do some more experiments for next Friday? And who would like to do some research on what people believed about falling before Newton published his theory?”
Bob’s hand shot up eagerly. “I have an idea for some experiments!”
“Great, Bob. Anyone want to work with him?”
“I will,” said Gail.
“Excellent. Now who would be interested in researching what people believed about falling long ago? Did the ancient Greeks have a hypothesis?” Grace raised her hand, and Marlene nodded along with her.
“Perfect. And do we know of anyone else who offered ideas about gravity before Newton?”
“Yes, Galileo dropped stuff off of the Tower of Pisa and wrote about that,” offered Marlene.
“Right, so include Galileo in your research. Jennifer, can you be prepared to tell us exactly what Newton said about falling stuff and what experiments he did?”
“Yes, of course. I still have my posters from last year’s presentation,” said Jennifer.
“Ok, class dismissed.”
What do you think? Can we really “see” gravity? And if we can’t directly observe the causes behind natural phenomena, how do we distinguish between good science and mere speculation? Join us next time as the students dive deeper into these questions…