Consider: two scientists are asked whether there's any doubt that humans are responsible for climate change. The first says, "It's a fact humans are causing climate change - there's no room for doubt." The second replies, "The evidence for anthropogenic climate change is overwhelming, but in science there's always room for doubt."
The first scientist is probably a more effective spokesperson for the scientific consensus. But the second scientist is providing a more accurate representation of how science works.
This example defines the tension at the boundary between the realms of science and public opinion.
Is the aim of scientific advocacy to compellingly communicate particular scientific ideas, or to instill a way of understanding the natural world? Should scientists defend science or model science?
Take the following claims for which we have strong scientific support: current agricultural practices are contributing to climate change; taking unnecessary antibiotics can accelerate the evolution of antibiotic-resistant bacteria; and attending a high-quality preschool can have long-lasting benefits for a young child's learning and development. It matters whether people accept these claims because the information can influence how they eat, whether they follow their doctors' instructions and whether they support funding for early childhood education.
It's no wonder that scientists are eager to get certain messages across, and sometimes do so in a way that sacrifices scientific nuance for immediate persuasive force.
On the other hand, there's a lot to be said for effectively modeling science. Science is the most powerful tool we have for understanding the natural world. Its power stems from the very nuance that forceful slogans typically gloss over. Science is powerful because it is responsive to evidence - to the observed state of the world - and not to whims, wishes or faith. But with this power comes great liability: the potential to be wrong.
If this potential - and the uncertainty it entails - is a symptom of the very feature that makes science so reliable, then acknowledging uncertainty shouldn't undermine belief in scientific claims. If anything, it should have the opposite effect: modeling science should effectively defend science.
In a 2008 paper, Anna Thanukos, Michael Weisberg and I found evidence that this may be so: undergraduate students who understood that scientific theories are subject to ongoing testing and revision were more likely, not less likely, to accept evolution.
If you don't need to be a scientist for firm scientific beliefs to merrily coexist with scientific uncertainty, why the pressure to present science in overly-confident sound bites?
First, contemporary political discourse seems to equate an acknowledgment of the potential to be wrong with a lack of conviction. Imagine the fate of a political candidate who says, "I currently support school vouchers, but that endorsement could change in light of evidence concerning the impact of vouchers on students, families, schools, and communities."
In making this kind of talk taboo, we effectively support the opposite perspective: that an endorsement of school vouchers (for instance) should be insensitive to what we know or come to learn about their intended or unintended effects.
Second, some baseline understanding of science may be necessary for scientific uncertainty to corroborate rather than corrode belief in scientific claims.
In a 2012 paper, Anna Rabinovich and Thomas Morton found that people who saw science as an ongoing debate were more motivated to adopt environmentally-conscious behavior when messages about climate change acknowledged the existence of scientific uncertainty. For participants who saw uncertainty as "a sign of imperfect knowledge," messages that conveyed greater uncertainty were (nonsignificantly) less likely to motivate environmentally-conscious behavior. This suggests that, for many people, forceful statements of unwavering commitment are more effective calls to action.
Now let's consider the two scientists we started with as parents. The first says, "Never touch the oven; it's always hot." The second says, "Be careful around the oven; it's often hot." The first warning may be more successful when it comes to stopping a toddler in her tracks. But the second warning is more accurate and may have additional advantages. For example, it won't be rejected wholesale after an accidental brush with a cool oven, and it supports useful generalizations (e.g., when the oven needs to be cleaned, it's OK to touch if it's cool).
Overstating confidence in scientific claims may similarly miss a long-term benefit for a short-term advantage: rhetorical oomph comes at the cost of an opportunity to educate people about how science works and why the products of science are our most reliable guides to the natural world.
When your toddler is running toward a hot oven, you may be willing to sacrifice a teaching moment in a desperate effort to keep those little hands intact. When it comes to climate change, we're in a similar situation. Can we afford anything short of the most compelling calls to action? On the other hand, can we risk perpetuating ignorance about the values of science?
Guest blogger Tania Lombrozo is an assistant professor of psychology at the University of California, Berkeley. You can keep up with more of what Tania Lombrozo is thinking on Twitter: @TaniaLombrozo