Author(s): Michael S. Pritchard, Department of Philosophy, Western Michigan University & Theodore Goldfarb, Department of Chemistry, State University of New York at Stony Brook
NOTE: This contribution appeared as a featured resource in the online and printed issues of ENC Focus: A Magazine for Classroom Innovators Vol. 8 no.3, published by the Eisenhower National Clearinghouse for Mathematics and Science Education-ENC.
An examination of Millikan's own papers and notebooks reveals that he picked and chose among his drops. That is, he exercised discrimination with respect to which drops he would include in published accounts of the value of e, leaving many out. Sometimes he mentioned this fact, and sometimes he did not. Of particular concern is the fact that in his 1913 paper, presenting the most complete account of his measurements of the charge on the electron, Millikan states It is to be remarked that this is not a selected group of drops but represents all of the drops experimented upon during 60 consecutive days. However, Millikan's notebook shows that of 189 observations during the period in question, only 140 are presented in the paper.
Millikan's results were contested by Felix Ehrenhaft, of the University of Vienna, who claimed to have found "subelectrons." Moreover, Ehrenhaft claimed that his finding was in fact confirmed by some of Millikan's own data -- droplets that Millikan had mentioned but discounted in his published writings. The result was a decades-long controversy, the "Battle over the Electron," over whether or not there existed subelectrons, or electrons with charges of different values. This controversy makes an excellent case study because we are fortunate, thanks to Millikan's notebooks, to be able to see very specifically which drops he included and which he did not.
In retrospect, we know that Millikan was right and Ehrenhaft wrong. Electrons, to the best of our present experimental and theoretical knowledge, have a specific, discrete charge.
Those scientists and other scholars who have carefully reviewed this case have failed to agree on whether Millikan was guilty of unethical behavior or "bad science" in the treatment and presentation of his data. One of the expressed opinions condemns Millikan on the simple basis of the fact that his published statement is at odds with what can be concluded from an uncritical examination of his laboratory notebooks. Others exonerate Millikan on the basis of a careful analysis and interpretation of comments on the data that appear in the notebooks. In the opinion of these Millikan defenders, the assertion that all drops were presented in the paper refers to all of the data taken under those conditions when the apparatus was working properly. Some of the scientists who have commented on this case appear to permit Millikan much discretion in the use of his "scientific intuition" to decide which data to include or exclude. This latter view seems to be guided by the principle that any scientist who consistently gets what turns out to be the correct answer is doing good science.