Some of the most important decisions leaders make come with incomplete evidence. You can study the data, test assumptions, and weigh the risks. At some point, you still have to decide without knowing for sure.
That tension is playing out right now in the debate over autism.
The White House recently signed an executive order on childhood vaccines that revisits the immunization schedule and widens autism research, the Associated Press reported. Health Secretary Robert F. Kennedy Jr. promised the government would soon name what he calls an environmental factor behind rising diagnoses.
Autism diagnoses have climbed to 1 in 31 eight-year-olds, up from 1 in 150 in 2000, according to the CDC. The agency also says decades of studies show childhood vaccines don’t cause autism, and it ties much of the increase to broader screening and awareness. Researchers still can’t say how much of the rise reflects a true increase versus better detection, and the numbers alone can’t settle it.
That uncertainty fuels the debate. One side sees the absence of proven harm as evidence of safety. The other sees the absence of proven safety as reason for concern.
Business leaders face their own versions of this problem all the time: how do you make a good decision when the evidence may never give you a definitive answer?
Why Certainty Is a Trap
Most consequential business decisions can’t be proven in advance because they usually involve large amounts of uncertainty. You can collect evidence, estimate probabilities, and challenge your assumptions. Eventually, you reach the point where more analysis still won’t produce a definitive answer.
The reality is that in today’s complex world, we must make concrete decisions without concrete data.
Leaders tend to make one of two mistakes when the evidence is incomplete. The first is requiring proof before acting. It sounds rigorous, but while you wait, someone else moves first and starts learning faster.
The second is assuming that because something hasn’t been disproven, it deserves a major investment. That can turn uncertainty into an excuse for making a poorly supported bet.
The problem with autism, as well as other topics that require cause and effect insight, is that there are just too many variables to isolate the single risk factor or success factor. Correlation doesn’t equal causation. As soon as you move outside physical science, it’s quite difficult to gain extreme certainty. This applies to market research, sociology, psychology, management, leadership, and the list goes on.
Stop Asking the Wrong Question
Cancer offers a useful analogy. There’s no single cause, yet researchers and policymakers didn’t wait for one definitive explanation before acting on what they learned.
We learned that smoking drives lung cancer, that HPV causes most cervical cancers, and that ultraviolet light raises skin cancer risk. Each finding prevents cases without solving the whole puzzle.
Business decisions work the same way. Asking “Will this work?” often demands a level of certainty the evidence simply can’t provide.
The self-driving car company, Waymo, shows another approach. Its cars have driven 170 million miles with 92% fewer serious-injury crashes than human drivers. Waymo can’t prove perfect safety. It operates based on strong evidence. It monitors what happens and adjusts its algorithms as new data comes in.
Four Questions When Proof Is Impossible
When the data can’t give you certainty, ask four questions:
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- How strong is the evidence we already have?
- How large could the impact be?
- What single piece of new information would change our minds?
- What do we do while the uncertainty remains?
Those questions shift the discussion from proving whether something is true or false to deciding what the available evidence justifies doing now.
Then, put your new thinking into practice:
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- Set an evidence threshold. Decide in advance what level of evidence is enough to act, rather than waiting indefinitely for certainty.
- Make bets reversible. Start with decisions you can change or unwind so the cost of being wrong stays relatively low.
- Build an update loop. Set a specific point to revisit the decision when new evidence becomes available.
The vaccine debate shows how each side can use uncertainty to bolster their claims. The better discipline is to determine what the evidence supports now, act accordingly, and remain willing to change course as new data emerges.
This Week
Pick one decision you’ve been postponing until you have absolute certainty. Write down the evidence you have, the size of the upside and downside, and the one fact that would change your answer. Then set the threshold that lets you move forward before you have proof.
Leaders who learn to make sound decisions without proof learn to move forward while others are still waiting while watching others pass them by.
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