What is "cargo cult" in software development?

Let's start with a bit of history:

During World War II, American forces occupied several strategic military bases in the Pacific area, which had to be regularly resupplied with food, weapons, and equipment of all kinds, most of the time by air.

Since these key points were located on islands inhabited for thousands of years by local ethnic groups, it regularly happened that soldiers would "trade" certain parts of their supplies with the peoples of these islands, who had never before had any contact with industrial technology.

But at the end of the war, the peoples of these islands saw the American soldiers leave overnight, taking with them the remains of this technology so different from their own (industrial clothing, canned food, etc.).

The "cargo cult"

In French, "cargo" means "cargaison" ["cargo/freight"], and this expression refers to the esoteric practices of these ethnic groups whose civilizations had been infiltrated by the presence of new technology, and for whom the drops of supply cargo coming from the sky looked exactly like a divine intervention.

Religious behaviors could then be observed among some of these tribes, which consisted of reproducing the appearance of the technologies used during the war, but with rudimentary materials, in the hope that by seeing these figures their gods would start sending cargo from the sky again.

Often built from wood, straw, rope, and leaves, some of the creations of this "cargo cult" are quite astonishing, even though of course, only the shape of the object was reproduced.

Here are a few example photos from these islands depicting planes, satellite dishes, and aviator glasses:

Use in software development

Beyond the historical reality, the expression "cargo cult" has since found a meaning in the modern world, referring to practices repeated "blindly" with the goal of solving a problem without really thinking about "why" or "how" to implement this solution.

One could simplify this practice as follows: "If it worked for others, let's do exactly the same thing to solve our problems."

In software development, this term was first introduced by Steven McConnell, author, software engineering expert, and former developer at Microsoft and Boeing.

McConnell was referring to software development approaches that are often copied, imitated, from one company to another without really understanding the point of this or that practice.

The "cargo cult" is notably used to describe (criticize) the implementation of certain project management methodologies (Agile for example) in companies, but also sometimes to describe the way some developers copy-paste code hoping it will work, without always knowing why.