Anytime any being takes an action, there are both intended and unintended consequences, also called externalities. When a forest is cut for lumber, the intention is to use that wood to build houses, boats, etc. (oh yeah, and make a profit). This is the intended consequence and these usually are far fewer in number than the unintended consequences. This action of clear cutting an entire forest has huge numbers of devastating externalities such as soil erosion, disruption in rainfall patterns, desertification, species and habitat destruction, as well as a loss of something intuitively sacred.
Conventional economists do rightly speak of externalities in textbooks and how serious they can be. But many have ignorantly assumed an inexhaustible supply of natural resources to fuel economic growth indefinitely. They also assume the Earth has an infinite capacity to absorb externalities. In such a world of infinite resources and infinite capacity to absorb pollution, externalities have little consequence. It is when the cumulative effect of all those externalities begins to erode the capacity of the planet to support life that we start to see the real threat externalities pose to all of life on Earth.
This inspiring video points out the fallacy of conventional economics – a belief that there are no limits – and provides a hopeful model with which to frame our vision for the future.