In part because individual judgement is not accurate enough or consistent enough, cognitive diversity is essential to good decision making.

The value of a currency is, ultimately, what someone will give you for it - whether in food, fuel, assets, or labor. And that's always and everywhere a subjective decision.

Diversity and independence are important because the best collective decisions are the product of disagreement and contest, not consensus or compromising. An intelligent group, especially when confronted with cognition problems, does not ask its members to modify their positions in order to let the group reach a decision everyone can be happy with. Instead…the best way for a group to be smart is for each person in it to think and act as independently as possible.

The paradox of Steve Jobs's career is that he had no interest in listening to consumers - he was famously dismissive of market research - yet nonetheless had an amazing sense of what consumers actually wanted.

Being out of a job can erode people's confidence and their sense of possibility; and employers, often unfairly, tend to take long-term unemployment as a signal that something is wrong.

Intellectual-property rules are clearly necessary to spur innovation: if every invention could be stolen, or every new drug immediately copied, few people would invest in innovation. But too much protection can strangle competition and can limit what economists call 'incremental innovation' - innovations that build, in some way, on others.

Since the Protestant majority in Northern Ireland wants to remain a part of Great Britain, and since Ireland itself has shown little interest in reunification, the IRA's prospects for success through political channels have always been limited.