The Edisonian approach to invention is characterized by trial and error discovery rather than a systematic theoretical approach. An often quoted example of the Edisonian approach is the successful but protracted process Thomas Edison is reported to have used to develop a practical incandescent light bulb. Inventor Nikola Tesla is quoted as saying "[Edison's] method was inefficient in the extreme, for an immense ground had to be covered to get anything at all unless blind chance intervened and, at first, I was almost a sorry witness of his doings, knowing that just a little theory and calculation would have saved him 90 percent of the labour" (Wills I. (2019) The Edisonian Method: Trial and Error. In: Thomas Edison: Success and Innovation through Failure. Studies in History and Philosophy of Science).
Based on detailed study of his notebooks a number of scholars have pointed out that Edison generally resorted to trial and error in the absence of, or lack of awareness of, adequate theories. For example, in developing the carbon microphone (or carbon grain transmitter) that became the basis of telephones of the next hundred years, Edison and his co-workers tried hundreds of substances, finally settling on lamp black as the variable resistance medium. Edison could not use theory to solve this problem because, as Gorman and Carlson note, at the time "no one had yet developed a chemical theory that Edison could have used to identify a form of carbon with the electrical properties he wanted" (Gorman and Carlson, 1990).
Edison was not alone in using trial and error (more accurately termed by Hughes as "hunt and try") because he, like others, was working at the edges of contemporary theory. Thomas Midgley (who held a PhD and was the inventor of tetraethyl lead and halogenated hydrocarbon refrigerants) said of trial and error, "the trick is to turn a wild goose chase into a fox hunt" (quoted in Hughes 2004).
Edison used a "bottom-up theoretical approach" when developing electric lighting, undertaking detailed analysis of the whole electric lighting system based on Joule's and Ohm's laws. This led him to conclude that to be economically successful he had to produce a high resistance lamp (around 100 ohms). (Friedel and Israel 1987) Once he had established the need for a high resistance lamp he was faced with a lack of optical emission theories to describe the behaviour of materials when heated to incandescence. It was then that he embarked on a systematic search for a suitable material and for the techniques to manufacture it in economic volumes.
Historian Thomas Hughes (1977) describes the features of Edison's method. In summary, they are:
Edison is quoted as saying, "When I want to discover something, I begin by reading up everything that has been done along that line in the past - that's what all these books in the library are for. I see what has been accomplished at great labor and expense in the past. I gather data of many thousands of experiments as a starting point, and then I make thousands more."
Friedel, Robert, and Paul Israel. 1987. Edison's electric light: biography of an invention. New Brunswick, New Jersey: Rutgers University Press.
Hughes, Thomas P. 1977. Edison's method. In Technology at the Turning Point, edited by W. B. Pickett. San Francisco: San Francisco Press Inc., 5-22.
Hughes, Thomas P. 2004. American Genesis: A Century of Invention and Technological Enthusiasm 1870-1970. 2nd ed. Chicago: The University of Chicago Press.
Gorman, Michael E., and W. Bernard Carlson. 1990. Interpreting invention as a cognitive process : the case of Alexander Graham Bell, Thomas Edison and the telephone. Science, Technology and Human Values 15 (2):131-164.