• Sustainable Or Unsustainable  Human economic activities are either sustainable or not.  This dichotomy is more important than how unpleasant environmental problems appear.
• Sustainable Scale  There are various levels of sustainable scale.  Two important benchmarks are Maximum Sustainable Scale and Optimal Scale.
• Unsustainable Scale There are various levels of unsustainable scale; resilience may allow recovery from low levels of unsustainable scale. If Maximum Scale is exceeded there is no recovery of the ecosystem functions destroyed.
• Scale Policy Implications Sustainable is better than unsustainable; current unsustainable practices should be fixed immediately; Maximum Scale is to be avoided; Optimal Scale is a policy priority.