Is Science simply a matter of opinion?

Humanity is confronted with a number of issues whose solutions rest on the answers to scientific questions.

Take just two topical examples: one from the science of climatology and the other from the science of economics.

First, climatology. The issue here is what has come to be known as climate change. Al Gore and the Intergovernmental Panel on Climate Change (IPCC), a UN panel of scientists and other experts, shared the 2007 Nobel Peace Prize "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change." In fact, there is currently a global campaign (Earth Hour) to switch off all the lights for one hour this coming Saturday 28 March 2009 at 20:30 local time all over the planet. The purpose is to highlight climate change. There's only one problem: There are other scientists and experts who question the scientific validity of climate change. Who is right? Is it all simply a matter of "everyone is entitled to their own opinion"?

Second example: economics. Noting (and ignoring for now) the view that economics is not a science at all, how is that some economists say "fiscal stimulation" is the only way to solve the global economic crisis whilst other economists say that it will lead to economic disaster. Who is right and who is wrong?

The basic premise of all scientific inquiry is that a natural or artificial phenomenon or system, be it the global climate or the global economy, exhibits order and is capable of being objectively and rationally explained and understood. Understanding forms the basis of prediction, design and control. Science, in its proper sense, cannot simply be a subjective matter. If it is, it ceases to be science.

The first and most important thing to realise on these important scientific issues is that two equal and opposite answers to the same question cannot both be right. Fully accepting this fact naturally leads to the next steps: ascertaining the criteria for assessing truth or falsehood; applying the criteria; embracing the truth and rejecting falsehood.