Arbitrary standards of evidence

The kinds of facts or evidence required to establish proof of the existence of a problem tend to vary across disciplines and social sectors. Such proof will clearly be resisted by authorities who need to protect their vested interests by denying the phenomenon as long as possible. A principal means of doing so is to impose stringent standards of proof, possibly much higher than those otherwise practised within that jurisdiction.

There have been many delays in officially recognizing environmental problems because of inability to establish "a link" between supposed causes and effects. Examples have included: emissions and acid rain, smoking and lung cancer, traffic emissions and ill-health.