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There is a compelling story, so beloved of professional problem solvers that it has become a virtual “article of faith” in the 5-Whys community. So compelling, that although the work predates Google by almost a decade, and despite never warranting an official publication, there are nevertheless more than 140,000 pages online which reference the study in some way.

To recap, 5-Whys is a simple, stripped-down method of root cause analysis (RCA) in which the investigator repeatedly asks, “why?” in order to drill down from higher-level symptoms to the underlying root cause(s) of a problem.

The story covers the woes of the Jefferson Memorial in Washington DC and dates back to the late 1980s when the National Parks managers noticed that the memorial was crumbling at such an alarming rate that it would quickly become dangerous to visitors. When they asked why this could be, they discovered that it was being washed far more frequently than any of the other DC memorials. For most investigations, the analysis would go no further. The solution is clear, of course. Reduce the cleaning schedule to match those of the other memorials.

Unfortunately, that solution would have only led to a very dirty, unhygienic Jefferson Memorial. This clearly wouldn’t do in a city of such national and international significance.  By employing classic 5-Whys thinking there was clearly more work to be done!

Next up the investigation team enquired as to why the memorial was being cleaned so frequently?  They discovered it had an exceptionally large amount of bird droppings deposited on it every day. What’s the solution now? Use scarecrows? Fly hawks? Bring in Elmer Fudd or the Duck Dynasty crew and declare open season on pigeons?

Luckily (for the pigeons, anyway), the Parks managers kept inquiring. When they asked why the birds seemed to soil Jefferson at rates higher than other nearby monuments like Kennedy or Lincoln, they discovered that the Jefferson harboured an incredibly large population of spiders and similar bugs upon which the birds were eagerly feasting. Why on earth was this?  An eminent entomologist, Prof. Don Messersmith was contacted, and he discovered that the population of spiders had exploded because of an abundance of midges and similar insects that had made the area around the monument their home.

When the Parks managers asked Prof. Messersmith why so many midges congregated on the Jefferson memorial, Messersmith told them what any fly- fisherman already knows - Midges are triggered to emerge and mate by a particular quality of gentle light.  And it just so happens that the Park managers had been inadvertently creating this unique quality of brightness by turning the memorial lights on just before dusk.
So, according to our tale, this one variable (light levels) caused this pattern of cause and effect; lots of midges, lots of spiders, lots of pigeons, lots of droppings, lots of chemicals during lots of washing – all leading to the deterioration of the statue. 

Expressed as classic 5-Whys we can illustrate this in the following way:

ProblemOne of the monuments in Washington D.C. is deteriorating.

Why #1 – Why is the monument deteriorating?  

  • Because powerful chemicals are frequently used to clean the monument.
Why #2 – Why are powerful chemicals needed?
  • To clean off the excessive volume of bird droppings on the monument.
Why #3 – Why is there an excessive volume of bird droppings on the monument?
  • Because the large population of spiders in and around the monument are a food source to the local birds.
Why #4 – Why is there a large population of spiders in and around the monument?
  • Because vast swarms of flying insects, on which the spiders feed, are drawn to the monument at dusk.
Why #5 – Why are swarms of insects drawn to the monument at dusk?
  • Because the lighting of the monument in the evening attracts the local insects.
Solution:  Change how the Jefferson is illuminated at dusk to prevent the arrival of swarming insects
The tale tells us that the solution ended up being incredibly simple and actually saved the Parks Department money, namely to just wait until dark to turn on the lights.

The Alternative (True) Take?

Except, what if it was never as simple as this?  What if, after 30 years of teaching this example, emboldening thousands upon thousands of 5-Whys disciples, leading to tens of thousands of articles we discover that the 5-Whys method didn’t actually uncover the layers of this problem and that the solutions chosen were not quite as simple, nor as effective as we have been led to believe all these years?
Let us investigate further via series of challenges gathered from information that is readily available in the public domain.

Debunk 1.  Although the tale speaks of the unique nature of the Jefferson Memorial official reports, published in 1989, state that several memorials across in DC were a similar condition, regardless of their unique environmental conditions

Debunk 2.  The investigations undertaken throughout 1989 and 1990 were not undertaken by plucky amateurs as implied by most iterations of the tale. In fact, they were part of an in-depth multi-disciplinary investigation performed by a team of highly trained problem solvers hired by the National Park Service (to the tune of $2 million) to perform a year-long study of the deterioration of DC memorials.

Debunk 3a.  Most versions of the story cite the harsh chemicals required to remove bird droppings as the ‘root cause’ of the problems effecting the monument’s stonework. Full study of the documents produced back in 1989/1990 state clearly that although chemicals did contribute they only contributed in combination with other factors. Most significantly the ‘excessive’ quantity of water used throughout the cleaning process, and the pressure at which it was applied. 

Debunk 3b. Furthermore, acid rain, air pollution and littering tourists were also cited as contributing factors of note. News articles published at the time stated that the Parks Service must “dramatically reduce the volume of water used to wash the monuments”, even going so far to say that they would need to “educate the public to understand that these buildings may not appear as pristine white in the future as they once did” because of the reduction in water used to clean them.

Debunk 4.  Reports also stated that the majority of the discolouration was not caused by bird droppings.  It was, in fact, the midges and bugs themselves that discoloured the stonework.  It is true, nevertheless, that the lighting used, did attract the insects to the buildings.

Debunk 5a. The impact of the Jefferson Memorial story is delivered by the fact that the chosen solution (to delay lighting till full darkness, and reduce overall brightness) was more effective, quicker and far lower in cost than any other consideration.  In the first instance, this solution was extremely effective, reducing bug communities by 85% within just a few weeks.  However, the replacement lighting systems across the city took a full 5 years to implement and eventually cost upwards of $25 million in public money.

Debunk 5b. Although the solution was extremely effective (and ultimately saved on energy costs too) it was never implemented beyond a 6-week trial period!  After several years of lobbying from various public bodies and complaints from residents, businesses, tourists and photographers, fearful of being robbed of their stunning images of great monuments glowing next to the mighty Potomac River, the government finally abandoned their decision to fully restrict lighting levels in the early evenings. A timely reminder that in the real world some solutions can be extremely effective as well as offer an undeniable return on investment but, due to strategic, environmental or cultural (and unforeseen) obstacles can never be implemented.

Debunk 6. In place of the highly effective, but short-lived decision to change the lighting policy there are now a host of solutions in place to dissuade birds, spiders and midges from congregating on the memorials. These reportedly include the installation of wires, metal spikes, netting, scarers and clear plastic.  The cleaning processes have also changed; the quantity of water has been reduced and the way in which it is applied has changed. And, crucially, the chemicals that are used are now far less aggressive.  Fundamentally though, the demands of the viewing public have changed, leading to a more realistic and pragmatic expectation of the appearance of the monuments.

What have we learnt here?

Firstly, Satirist HL Mencken, from nearby Baltimore, couldn’t have been more apropos when he wrote half a century earlier that ‘For every complex problem there is an answer that is clear, simple, and…wrong’. The answers delivered in this story were clear, they were simple, and they were, alas, also wrong.

But like all good debunked stories, there is still much to be learnt from the apocryphal tale of the Jefferson memorial. Just maybe not exactly what we thought.  Perhaps what we really gain here is a more realistic picture of the huge difficulty of solving complex problems under real world conditions.  And that only via a genuine understanding of cause and effect do we discover the wider spread of solutions that we almost always need to apply in the real world.  But crucially, we are reminded that when a lesson is this plausible, almost all of us are blind as to its questionable validity.  

So, let us keep sharing the Jefferson Memorial story, but not simply as an uncritical encouragement to adopt 5-Whys as an RCA method, but as a warning not to be seduced by its apparent simplicity. 5-Whys will certainly help us get beyond the symptoms of a problem, and it’s certainly fast to use, but the true causes of any incident are always more complex than just a few simple steps back through the causal chain.


Root Cause Analysis training by Sologic provides the tools, skills, and knowledge necessary to solve complex problems in any sector, within any discipline, and of any scale.
Learn More


Sologic’s Causelink has the right software product for you and your organization. Single users may choose to install the software locally or utilize the cloud.  Our flagship Enterprise-scale software is delivered On Premise or as SaaS in the cloud.
Learn More