In 1922 William F. Ogburn and Dorothy Thomas published a paper entitled “Are Inventions Inevitable? A Note on Social Evolution.” The paper starts “It is an interesting phenomenon that many inventions have been made two or more times by different inventors, each working without knowledge of the other’s research.” In their paper, Ogburn and Thomas list 148 instances of dual discovery made between 1420 and 1901.

Sociologist Robert K. Merton refers to dual scientific discovery as “multiple independent discovery” and posited that they are a common pattern in scientific discovery – more the rule than the exception – and the incidence of multiple independent discoveries is increasing.

The most famous multiple independent discoveries include:

• Sir Alfred Russell Wallace and Charles Darwin developed the theory of evolution simultaneously.
• The development of calculus by Isaac Newton and Gottfried Wilhelm Leibnitz (see also the IFOD Was Math Invented or Discovered?)
• The telephone by Elisha Gray and Alexander Graham Bell
• The discovery of oxygen by Carl Wilhelm Scheele, Joseph Priestley, Antoine Lavoisier, and others
• Link to big Wikipedia list of Multiple Independent Discoveries here.

The prevalence of multiple independent discoveries is surprising given the popular view of scientific discoveries is rooted in the “great man” or “genius” theory of discovery which holds that important scientific discoveries are primarily attributable to the great genius of the scientists that made the discoveries. These great men are thought to possess greater abilities and insights than their colleagues, and if these geniuses did not exist then the discoveries would not be made (or be greatly delayed until another genius came along).

Of course, all these simultaneous discoveries throw doubt on the great man theory of scientific discovery. So, why/how do we get these simultaneous discoveries?

One theory is called the “social determinism” or “zeitgeist” theory of creativity. This theory, according to social psychologist Dean Simonton, states that “the sociocultural system as a whole, embodied as the spirit of the times [zeitgeist], is ultimately responsible for any given technoscientific advance.” This theory suggests that conditions must be right for any particular discovery in terms of the necessary building blocks of scientific knowledge and cultural acceptance and support of the discovery. Ideas may have a unique time in history in which they are ripe for discovery. But, once the pre-conditions exist it is not suprising that discovery is made by more than one person.

Another explanation is chance. Periodically, great geniuses appear in various fields due to chance and, statistically, sometimes there will be more than one such genius at the same time. Supporting the theory of chance is the fact that the number of multiple discoveries loosely follows a statistical pattern called a Poisson Distribution which shows the likely number of times an independent event will occur within a period of time. Given the great number of scientific discoveries, chance alone might dicate that some of them are discovered by multiple people indepdently.

Finally, another theory is that some (or most) simultaneous discoveries are not really new discoveries, but rather are mere repackagings or incremental improvements on a prior discovery. This idea is championed by Tertius Chandler, of the University of California, and gives the example of evolution really is based on the prior work of Thomas Malthus. From Cal Berekely:

Interestingly, Darwin and Wallace found their inspiration in economics. An English parson named Thomas Malthus published a book in 1797 called Essay on the Principle of Population in which he warned his fellow Englishmen that most policies designed to help the poor were doomed because of the relentless pressure of population growth. A nation could easily double its population in a few decades, leading to famine and misery for all.

When Darwin and Wallace read Malthus, it occurred to both of them that animals and plants should also be experiencing the same population pressure. It should take very little time for the world to be knee-deep in beetles or earthworms. But the world is not overrun with them, or any other species, because they cannot reproduce to their full potential. Many die before they become adults. They are vulnerable to droughts and cold winters and other environmental assaults. And their food supply, like that of a nation, is not infinite. Individuals must compete, albeit unconsciously, for what little food there is.

It seems to me like a huge stretch to say that Malthus discovered evolution, but the above does support the concept that ideas have their unique time in history and are based on prior thoughts and discoveries, allowing multiple geniuses to make simultaneous, independent breakthroughs.

Some of the concepts relayed in this IFOD are based on a paper by Dr. Eugene Garfield and this article from Fast Company.