Defining Consensus
Another important issue to consider when someone contends that there is a “scientific consensus on global warming” is what exactly is being agreed upon and by whom. Yet, in the heat of the political controversy, no one seems preoccupied with specifying the what and the whom. The validity of the contention, however, depends crucially on defining its terms appropriately.
Thomas Sowell wrote in The Vision of the Anointed that “all statements are true if you are free to redefine their terms.” If everyone is free to define the terms “scientist”, “consensus”, and “global warming” then it may well be that there is a “scientific consensus on global warming.” But if we are more careful in defining what these terms mean, then the contention that a consensus exists melts in the air.
Who are the scientists?
Who are the “scientists” that must agree so that the so called consensus be scientific? Do they have to have a PhD in climatology or meteorology or is a M.Sc. in arts or history of science enough? Are they required to have academic publications in relevant peer reviewed journals? Do they have to be associated with the IPCC, or is association with a nonprofit research institution enough? It seems that all it takes for one to be counted as a scientist is to have a particular opinion about the state of the world, namely, that it is warming: whoever agrees becomes a scientist. Never in history there was such a low bar for being called a scientist.
How many scientists?
How many scientists must agree for a consensus to be established? A consensus requires unanimity, or the “collective unanimous opinion of a number of persons” (Oxford English Dictionary), not simply majority. There may well be many scientists that think that the world is warming, and the causes, the extent and the consequences of this warming, but it is obviously not the case that everyone agrees. One consequence of using the term “consensus” wrongly, namely as a synonym of majority, is that the discussion is averted; it revolves around the sizes of two lists: one including scientists who think that the world is warming and human beings are responsible and another including scientists who think that the matter is not so simple. But lists and their size prove nothing! The only thing that two lists may indicate is that not all scientists agree, i.e., that there is no consensus. Be that as it may, it is impossible to compare two lists: By what criteria one list is better than another?
What is the agreement about?
Finally, what exactly is the agreement about? That the temperature of the earth has been increasing and that it will continue to increase? But when exactly did the increase begin and for how long will it last? Is C02 the sole reason for the increase? Will a decrease in the level of C02 necessarily lead to a cooling of the globe? Is it possible to control how much cooler the world will be? Clearly the globe is not a room with a thermostat. The relationship between cause and effect is often intricate and always difficult to prove. Yet, it is not obvious that by reversing the direction of the possible causes of global warming, the effects will disappear (i.e., the globe will cool). Are there only negative consequences related to climate change, or are there positive ones as well? Are human beings responsible for global warming or are there other culprits? What can and should we do about it?
Forecast & Planning
