As outlined in an Apple white paper, Challenge-Based Learning encourages students and teachers to work together to define problems, propose solutions, and then execute those solutions.

FORBES: How Sandy Can Help Students Become Better Citizens

Development groups are nervous about attempts to define a hierarchy of global problems with population at the peak.

BBC: Harrabin's Notes: Population overload?

Attaching rights to carbon in standing forest, while easier to define, will run into similar problems in places where ownership of forestland and forest services are weak and ill-defined.

ECONOMIST: Letters

Monsanto famously tried to define its responsibility as solving the problems of agriculture through genetic engineering, only to find that many stakeholders felt it was irresponsible of Monsanto to modify genes.

FORBES: Clarifying Corporate Responsibility: Part II

But he seems like a man who would seek to define a clear message, tackling problems with a stern glee, a missionary zeal to challenge a world he feels has gone badly, sadly wrong, and that needs to be re-made in God's image, with the authority of Rome.

BBC: Pope: Will Canadian Cardinal Marc Ouellet be chosen?

What they discovered, it's not true, that homelessness is divided up, and there are a very small number of people who have very serious problems and who really make up what we define of and think of as chronic homelessness.

NPR: A Scientific Approach to Helping the Homeless