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Mental models are a way of explaining how things work. Throughout our lives, we build up a personal collection of mental models to understand the world around us.

Mental models aren't perfect but developing a rich toolbox of them can be useful in navigating the complexities of life. Learning to intuitively apply the right models in the right situations is something we develop with practice.

This website is a curated collection of models with broad applicability in everyday life. There’s a focus on brief descriptions and simple, real life examples of the models in use.


Weekly Mental Model

Diminishing Returns

In productive processes, the value gained from increasing one input but keeping others the same will at some point start decreasing.

Description

When producing something, there are inputs and results. The law of diminishing returns states that simply increasing one input but keeping others the same will at some point yield diminishing results. In some cases, this can be improved by adjusting other inputs appropriately. For example, if adding more workers to a factory, we can also add more machines and working space. In other cases, the production may be inherently difficult to parallelize.

Examples

  • Brook’s law states that just increasing headcount in a software project, will not make it ship faster. Ramp-up time, communication overhead, and the indivisibility of certain tasks may in fact slow it down.

  • In our personal lives, we may find that doing too much of something may lead to diminishing (or even negative) returns. For instance, over editing a piece of writing or continuing to tweak a painting.