The reason for that definition can be seen during jury trials when typically one expert will give an opinion for the plaintiff or prosecution, yet another expert will give an opposite opinion for the defendant.
Both are experts, and they are using the same evidence.
But our false notion that if we call an expert to help us with a problem we will derive one and only one concluding reality, thereby invalidating the rest of the possibilities, is more often than not caused by a love affair with oversimplification.
Of course there is also the spectre of perjury or lesser forms of dishonesty, and even incompetence.
But the point is that this contrast or contradiction can arise even when both experts are honest and have a sincere belief in their opinion.
Thus the oft quoted statement by experts as to their own opinion: "get a second opinion", means "I think others will agree with what I just told you".
But when there is contrast or contradiction in expert positions, in our system of law a jury must decide which expert is correct on the facts, not because we think non-experts know more than experts know, but because of our ancient, well founded beliefs, based upon the experience of our ancestors, that "power corrupts".
Daily we are a jury when we hear conflicting reports from experts about global warming, global climate change, and the peak oil concerns.
There is constant chatter and bickering back and forth about these issues, and experts are by no means in solid accord when it comes to solutions, even though there is major, growing consensus among experts as to these two realities.
As an example a discussion ongoing at a blog which discusses peak oil problems from many perspectives, considers the weaknesses and strengths of other experts in the field:
Can the IEA really be expected to be objective? I tried to look at this issue two years ago, when the World Energy Outlook 2008 was released. The organization of the IEA, its close ties to the OECD, and the significant funding of the IEA by the US gave me real doubts about its ability to be objective at the time of my analysis. I doubt the situation has changed a great deal in the last two years.(The Oil Drum). Meanwhile another group of experts came at the problem from a totally different part of the playing field:
At the current pace of research and development, global oil will run out 90 years before replacement technologies are ready, says a new University of California, Davis, study based on stock market expectations.(Science Daily, Journal Article). This issue matters to all of us because our lives and the lives of 6 billion other people will be affected by the eventual outcome of the discussion or debate.
Niemeier said the new study's findings are a warning that current renewable-fuel targets are not ambitious enough to prevent harm to society, economic development and natural ecosystems.
It is a life and death issue, your jury vote counts, so take time to make the best decision you can with what you have to make that decision.