Tesler’s Law, also known as The Law of Conservation of Complexity, states that for any system there is a certain amount of complexity which cannot be reduced.
The total complexity of a system is a constant. If you make a user’s interaction with a system simpler, the complexity behind the scenes increases.
Complexity is like energy. It cannot be created or destroyed, only moved somewhere else.
Removing functionality doesn’t make something simpler, because it removes options. Simple tools have a limited ability to simplify processes.
Trying to do something complex with a simple tool is more complex than doing the same thing with a more complex tool.
Looking at a workbench of tools or a digital photo editing program, a novice sees complexity. A professional sees a range of different tools, each of which is simple to use. They know when to use each to make a process easier. Having fewer options would make their life more complex, not simpler, because they wouldn’t be able to break what they need to do down into individually simple steps. A professional’s experience-honed conceptual model helps them navigate a wide range of tools.
Complexity is necessary because it gives us the functionality we need.
From a user’s standpoint, the simplest products and services are those that are fully automated and do not require any intervention (unless something goes wrong.)
As long as you pay your bills, the water supply to your house is probably fully automated. When you turn on a tap, you don’t need to have requested there to be water in the pipes first. The companies that manage the water supply handle the complexity.
Operational simplicity is the more important goal than perceived simplicity.
Sometimes we need to preserve a minimum level of complexity so that users feel like an actual participant. According to legend, cake mixes require the addition of a fresh egg because early users found that dried ones felt a bit too lazy and low effort.
Simplicity is not an end in itself—other things like speed, usability, and time-saving are. We shouldn’t simplify things from the user standpoint for the sake of it.
People want to feel in control, especially when it comes to something important. We want to learn a bit about what’s happening, and an overly simple process teaches us nothing.
A big challenge in the development of self-driving cars is that a driver needs to be able to take over if the car encounters a problem. But if someone hasn’t had to operate the car manually for a while, they may panic or forget what to do. So it’s a good idea to limit how long the car drives itself for. The same is purportedly true for airplane pilots. If the plane does too much of the work, the pilot won’t cope well in an emergency.