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发帖数: 29846 | 1 German Jewish Émigrés and U.S. Invention
via Cato Headlines
Immigration policy has been the subject of heated debate in the United
States. One key claim in support of high-skill immigration is that it spurs
innovation, but existing evidence is mixed. New research by Petra Moser,
Alessandra Voena, and Fabian Waldinger provides new evidence on this
question by examining the impact on innovation of German Jewish scientists
who fled from Nazi Germany to the United States after 1932.
“German Jewish Émigrés and U.S. Invention,” by Petra Moser
http://object.cato.org/sites/cato.org/files/pubs/pdf/researchbr
immigration, but highskill
immigration policy is also contentious. One
key claim in support of high-skill immigration is that it
spurs innovation, but existing evidence is mixed (Hunt
and Gauthier-Loiselle 2010, Kerr and Lincoln 2010, and
Borjas and Doran 2012).
Our research provides new evidence on this question
by examining the impact on innovation of German Jewish
scientists who fled from Nazi Germany to the United States
after 1932. Historical accounts suggest that these émigrés revolutionized
U.S. innovation. In physics, for example, émigrés
such as Leo Szilard, Eugene Wigner, Edward Teller, John von
Neumann, and Hans Bethe formed the core of the Manhattan
project that developed the atomic bomb. In chemistry,
émigrés such as Otto Meyerhof (Nobel Prize 1922), Otto
Stern (Nobel Prize 1943), Otto Loewi (Nobel Prize 1936),
Max Bergmann, Carl Neuberg, and Kasimir Fajans “soon effected
hardly less than a revolution. . . . Their work . . . almost
immediately propelled the United States to world leadership
in the chemistry of life” (Sachar 1992, p. 749).
Alternative accounts, however, suggest that émigrés’
contributions may have been limited due to administrative
hurdles and antisemitism. Jewish scientists met
with a “Kafkaesque gridlock of seeking affidavits from
relatives in America [and] visas from less-than-friendly
United States consuls” (Sachar 1992, p. 495). Once they
were in the United States, a rising wave of antisemitism
made it difficult for these scientists to find employment;
in “the hungry 1930s, antisemitism was a fact of life
among American universities as in other sectors of the
U.S. economy” (Sachar 1992, p. 498).
Our paper presents a systematic empirical analysis of
how German Jewish émigrés affected U.S. innovation.
Taking advantage of the fact that patents are a good measure
of innovation in chemistry, because chemical innovations
are exceptionally suitable to patent protection (e.g.,
Cohen, Nelson, and Walsh 2002; Moser 2012), we focus
on changes in chemical inventions. By comparison, the
contributions of émigré physicists (including those who
worked on the Manhattan Project) are difficult to capture
empirically because they produced knowledge that was
often classified and rarely patented.
2
The first component of our analysis compares changes
in U.S. patenting by U.S. inventors in the research fields
of German Jewish émigrés with changes in U.S. patenting
by U.S. inventors in the fields of other German chemists.
This approach allows us to control for a potential
increase in U.S. invention in fields where German chemists,
who had dominated chemical research in the early
20th century, were active inventors. Research fields are
measured at the level of 166 United States Patent Office
(USPTO) technology classes that include at least one
patent by an academic chemist from Germany or Austria
between 1920 and 1970. Baseline estimates indicate that
the arrival of German Jewish émigrés led to a 31 percent
increase in innovation after 1933 in the research fields of
émigrés.
These baseline estimates may be biased if the United
States attracted more productive scientists or if the émigrés
were more likely to work in research fields in which
U.S. inventors would become more productive. Historical
evidence, however, suggests that émigrés to the United
States may have been negatively selected, because Britain,
which was geographically and culturally closer to the
German university system, was the first refuge for many
émigrés (Ambrose 2001, p.215), and universities such as
Oxford and Cambridge were keen to offer employment to
the most prominent dismissed German scientists.
Historical accounts also suggest that selection into
research fields may have been negative because antisemitism
in the United States restricted access to the most
promising fields. For example, the U.S. chemical firm
Du Pont rejected the “father” of modern biochemistry,
Carl Neuberg, because he “looked” too Jewish (Sachar
1992, p. 495). According to Hounshell (1988, pp. 295–96),
hiring practices in Du Pont’s Chemical Department
“were flawed in one important respect: A strong strain of
anti-Semitism and sexism prevailed. . . . ” More generally,
Deichmann (1999, p. 3) explains that “biochemists and
physical chemists were accepted at American universities,
whereas organic chemists were not.”
To examine whether our baseline estimates over- or
underestimate the émigrés’ effects as a result of such patterns
of selection, we exploit the dismissal of Jewish scientists
by the Nazi government. On April 7, 1933, only 67
days after the Nazis assumed power in Germany, the Law
for the Restoration of the Professional Civil Service required
that “Civil servants who are not of Aryan descent are to
be placed in retirement” (Gesetz §3). After the annexation
of Austria in 1938, dismissals were extended to Austrian
universities, so the term “German scientists” includes
chemists from both countries.
Our extended analysis uses the pre-1933 fields of dismissed
chemists as a source of exogenous variation in the
fields of émigrés to the United States. Pre-1933 research
fields of dismissed German chemists are a good predictor
for the research fields of émigré chemists. Moreover,
the research fields that a chemist who was dismissed in
1933 chose to pursue before 1933 are unlikely to have depended
on expectations about the types of research that
would become productive in the United States after 1933.
Consistent with historical accounts of negative selection,
these estimates imply that émigrés generated a 71 percent
increase in patenting, suggesting the baseline estimates
under- rather than overestimates the émigrés’ benefits for
U.S. invention.
In the second part of the analysis, we investigate the
mechanism by which the émigrés’ arrival encouraged
innovation in the United States, using a new data set on
the patent histories of U.S. inventors in 166 separate fields
of chemical invention in our data. This analysis suggests
that the arrival of the émigrés encouraged U.S. invention
by attracting domestic inventors to the research fields
of émigrés, rather than by increasing the productivity
of incumbent U.S. inventors. Data on the prior patent
histories of entrants into the research fields of émigrés
indicate that the majority of entrants had not patented in
these 166 classes before 1933, suggesting that émigrés’
arrival affected an increase in invention, rather than a
shift across fields.
Additional data on the co-inventors of émigrés (and on
the co-inventors of co-inventors) suggest that the effects
of émigrés on U.S. invention may have been amplified and
made more persistent through their effects on a network
of co-inventors, who benefitted from collaboration with
the émigrés. Co-inventors of émigrés became active patentees
in the fields of émigrés especially after 1940, and
continued patenting through the 1950s. These patterns
suggest that a natural delay in the transmission of knowledge
from émigré professors to their U.S. collaborators
influenced the timing of the increase in U.S. invention.
In addition to co-inventors of the émigré professors,
co-inventors of co-inventors of the émigrés also substantially
increased their inventive activity in émigré fields
after 1933, and remained substantially more productive
throughout the 1950s and 1960s.
3
Finally, in interpreting these results, it is important to
remember that we observe only a small, albeit prominent
segment of the flow of German Jewish immigrants to
the United States. As a first step toward investigating the
effects of this broader flow, we document the research
activities of a group of more junior German chemists,
who had not yet become professors at German universities.
Patent data indicate that these more junior scientists
were active in the research fields of émigré professors,
suggesting these fields are a useful proxy for the fields of a
broader movement of German Jewish émigrés.
In sum, our research shows that high-skilled German Jewish
immigrants created large and persistent benefits for innovators
in the United States. In interpreting these results it is
important to keep in mind that the émigrés in our data were
exceptionally qualified scientists comparable to present-day
academic superstars. Our analysis indicates that policies,
which encourage the immigration of such scientists, can be
an effective mechanism to encourage innovation.
This Research Brief is based on Moser, Voena, and
Waldinger (2013), available at http://www.nber.org/papers/
w19962. All works cited are provided there. |
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