The Lily Pad Problem – Why We Mishandled Coronavirus

There is a problem you sometimes see on IQ tests that reads something like this:

If the number of lily pads on a pond double every day, and it takes 30 days for them to cover the entire pond, on what day is the pond half covered?

Many people answer 15 days, as that is the basic human intuition answer, but the correct answer is 29 days.

Now, imagine that the pond being fully covered in lily pads is a really bad thing, and your job is to watch the pond and warn someone if this comes close to happening. So you watch the pond, and for the first 26 days, the lily pads are doubling, but, at this point, only 1/16th of the pond is covered with lily pads. At this point, it doesn’t seem like much of a threat, but over the next 4 days, the lily pads take over.

Day 27, 1/8th of the pond is covered, and for the first time it seems like a noticeable jump, and makes you think you should watch more closely. Day 28 1/4th of the pond is covered, and you realize something must be done, but you only have 2 days. And marshaling the resources to do anything may take longer than that. Day 29 the pond is half covered. Day 30 you are done.

The best way to fix this is to let people know on day 15 that the lily pads have been doubling, and something should be done. But it is hard for others to listen and take that seriously. They would say things like “so what if they are doubling, it’s such a small number” or they will look at the total number of lily pads and the nominal growth since day 1 and thing you are just crazy. Or sometimes they will assume there are other natural circuit breakers in the system, something that will slow the lily pad growth.

The lily pads don’t seem to be a problem, so it is hard to move resources against them. This is the ultimate problem with many complex systems that have such explosion points – once you realize they are a problem, it is too difficult to stop.

I joined the Board of the New England Complex Systems Institute last year because I have believed for a long time that we are going to see more issues like coronavirus, and that existing mental models for dealing with them are not adequate. We need better policy at all levels of government and industry.

On day 15, when the lily pads are small, so many people will argue that draconian measures to stop the lily pads are not worth the economic damage or resource drain to fight. But, in some cases, this is about survival, or about the fact that once the lily pads cover the entire pond, fighting them off is a 100x harder and more expensive.

If you are interested in understanding more about this way of thinking, you should consider taking a NECSI course, or I recommend the book Logic of Failure.

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