By now you’ve probably encountered an acquaintance or family member who will confront you with: “How can you trust science, it keeps changing it’s mind. First coffee is good for you then it’s bad, then it’s good again. Same with eggs or cell phones or juice.” They even might dredge up how scientists were convinced before global warming that the earths climate was actually cooling.
How do you counter this argument, heck, even as a skeptic you may feel that way yourself sometimes? On the surface it does look like science keeps changing it’s mind, but is it reality or is it how it is presented to us?
The first thing to realize is that science isn’t a monolithic institution, it’s a bunch of curious people and organizations trying to find the answers to questions that interest them. There is no one authoritative source that says, “This is the truth.” The best we have is a consensus, the longer and more thoroughly a topic has been researched the more likely there is a strong scientific consensus, but not always. Plus even a strong consensus can be wrong when new evidence is brought to light.
Next, think about the last time you read an article or saw a news report about something that you have knowledge about. They got some of the facts wrong didn’t they? Now apply that to the rest of the news you consume. Do you really think they only make errors on the stories you know something about? No, just about every story has errors or biases or misquotes, you only notice the stories have errors when you have personal knowledge.
There’s also more subtle ways of confusing the issue. Let’s create a hypothetical series of reports about caffeine. One group publishes a paper that looks at the effect of caffeinated soda on the learning habits of first graders, lets say they find that theres a 30% decrease in attentiveness when first graders consume one or more caffeinated sodas per day as compared to students who consume no caffeinated sodas. What will the headlines read? “Caffeine Makes You Lose Your Focus.” Then another group publishes a study that looks at how well elderly women perform on memory tests . The study finds the women who drink 2 or more cups of coffee a day perform 5% better than women who drink less than 2 cups per day. The headline for this study reads: “Caffeine Improves Your Memory.” In all honesty, five years from now will you even remember the headlines, let alone the details of each study? No, you’ll remember one study said caffeine was bad and another said it was good.
So, lets dig deeper assume both studies were well designed. The studies look at two radically different groups of people, they aren’t studying the same effect, and they aren’t even studying the same beverage. It’s hard to make a meaningful comparison between the two studies. Even assuming the researchers tried to eliminate all the other confounding factors, there always could be some that they missed. Finally these are only single studies — they haven’t been replicated. Replication is a cornerstone of science. If a study can’t be replicated than it’s results are questionable at best.
My last point is the media doesn’t always distinguish between good studies and poorly designed studies. In fact there are many groups that cherry-pick results, using the poor studies and ignoring the good studies to promote their particular agenda. I’m sure you can think of some examples on your own.