individual. Finally, I make a claim for combining immunology’s lessons about
biological individuality with the lessons drawn from other biologicalfields.
3.1 From Early Reflections about Immunological
Individuality to the Concepts of“Self”and“Nonself”
The key contribution of immunology to the reflection on biological individual-
ity and identity ever since the end of the nineteenth century has been empha-
sized by historians and philosophers of thisfield over the last three decades
(Löwy 1991; Moulin 1991; Tauber 1994; Pradeu 2012; Anderson and Mackay
2014). Here my goal is not to go into the details of that history, but rather to
show how these early thoughts have been revisited in recent immunology.
The idea that immunological reactions had something to do with the ques-
tions of bodily individuality and identity was expressed as early as the end of the
nineteenth century by many scientists, including, for example, Charles Richet
(Richet 1894; Löwy 1991). The many attempts to transplant body parts (espe-
cially the skin, which happens to be, in fact, an extremely difficult transplanta-
tion) in the wake of the First World War, however, constituted an important
turning point, as it led many biologists and medical doctors to raise specifically
the question of the biological determinants of the uniqueness of each individual
and its capacity to recognize these unique determinants and to potentially detect
and respond to elements that differ from them (Loeb 1937; Medawar 1957).
Starting from the 1940s, Frank Macfarlane Burnet (1899–1985) (Burnet
1940; Burnet and Fenner 1949) framed the concepts of immunological“self”
and“notself”(later called“nonself”)(Löwy 1991; Moulin 1991; Tauber 1991;
Anderson and Mackay 2014). In its most basic form, the self–nonself frame-
work says that the elements originating from an organism (the“self”) do not
trigger an immune response, while elements foreign to this organism (the
“nonself”) trigger an immune response. Such a framework can account for the
rejection by the body of both infectious agents and grafts. The self–nonself
vocabulary played an important role in establishing the study of infectious
diseases as well as research on transplantation as subdomains of the science
of immunology.
Burnet saw as a major challenge the question of how an organism canlearnto
preserve the constituents of the“self.”Partly inspired by Ray Owen’s work on
chimerism (Owen 1945), Burnet postulated that, if foreign material was
implanted early in the embryo, no antibodies would develop against that
particular foreign material (Burnet and Fenner 1949). This was later confirmed
by experiments made by Peter Medawar’s group, showing that a tissue
implanted early in the mouse embryo could subsequently be tolerated
Philosophy of Immunology 15