The concept of multiple discovery (also known as simultaneous invention) is the hypothesis that most scientific discoveries and inventions are made independently and more or less simultaneously by multiple scientists and inventors. The concept of multiple discovery opposes a traditional view—the "heroic theory" of invention and discovery. Multiple discovery is analogous to convergent evolution in biological evolution.
Multiples
When Nobel laureates are announced annually—especially in physics, chemistry, physiology, medicine, and economics—increasingly, in the given field, rather than just a single laureate, there are two, or the maximally permissible three, who often have independently made the same discovery.
Historians and sociologists have remarked the occurrence, in science, of "multiple independent discovery". Robert K. Merton defined such "multiples" as instances in which similar discoveries are made by scientists working independently of each other. Merton contrasted a "multiple" with a "singleton"—a discovery that has been made uniquely by a single scientist or group of scientists working together. As Merton said, "Sometimes the discoveries are simultaneous or almost so; sometimes a scientist will make a new discovery which, unknown to him, somebody else has made years before."
Commonly cited examples of multiple independent discovery are the 17th-century independent formulation of calculus by Isaac Newton, Gottfried Wilhelm Leibniz and others, described by A. Rupert Hall; the 18th-century discovery of oxygen by Carl Wilhelm Scheele, Joseph Priestley, Antoine Lavoisier and others; and the theory of evolution of species, independently advanced in the 19th century by Charles Darwin and Alfred Russel Wallace. What holds for discoveries, also goes for inventions. Examples are the blast furnace (invented independently in China, Europe and Africa), the crossbow (invented independently in China, Greece, Africa, northern Canada, and the Baltic countries), and magnetism (discovered independently in Greece, China, and India).
Multiple independent discovery, however, is not limited to only a few historic instances involving giants of scientific research. Merton believed that it is multiple discoveries, rather than unique ones, that represent the common pattern in science.
Mechanism
Multiple discoveries in the history of science provide evidence for evolutionary models of science and technology, such as memetics (the study of self-replicating units of culture), evolutionary epistemology (which applies the concepts of biological evolution to study of the growth of human knowledge), and cultural selection theory (which studies sociological and cultural evolution in a Darwinian manner).
A recombinant-DNA-inspired "paradigm of paradigms" has been posited, that describes a mechanism of "recombinant conceptualization". This paradigm predicates that a new concept arises through the crossing of pre-existing concepts and facts. This is what is meant when one says that a scientist or artist has been "influenced by" another—etymologically, that a concept of the latter's has "flowed into" the mind of the former. Not every new concept so formed will be viable: adapting social Darwinist Herbert Spencer's phrase, only the fittest concepts survive.
Multiple independent discovery and invention, like discovery and invention generally, have been fostered by the evolution of means of communication: roads, vehicles, sailing vessels, writing, printing, institutions of education, reliable postal services, telegraphy, and mass media, including the internet. Gutenberg's invention of printing (which itself involved a number of discrete inventions) substantially facilitated the transition from the Middle Ages to modern times. All these communication developments have catalyzed and accelerated the process of recombinant conceptualization, and thus also of multiple independent discovery.