The Great Mental Models, Volume 2: Physics, Chemistry and Biology

by Shane Parrish

Inertia is a useful model to try to understand some elements of our behavior, including our thinking patterns and habits. Our natural inclination to reject the new is in part normal resistance to the effort required to change. Keeping things as they are requires almost no effort and involves little uncertainty. We need force to effect change, and force requires effort. This model offers a lens to help us understand resistance to change and why we fail ourselves when we get complacent. Inertia implies that once we stop doing something, getting started again is harder than continuing the whole time would have been. At a basic level, many brain studies have shown that the idea of multitasking is a myth. When we shift our focus from one input to another, we exert more energy and use more time to finish everything than if we would have completed one task before starting another. Inertia also helps to explain why we continue on with bad habits and why it’s hard to make systematic change. Many cities continue to rely on cars for short commutes instead of implementing an infrastructure to facilitate public transportation, walking, or cycling. We stay at jobs we hate, avoid meaningful conversations with people of different opinions, and almost never change the religion our parents imposed on us at birth. All because it is easier to stay on our current path, however stagnant and unfulfilling it may be.—