  It will be presented in this chapter a historical account of the consistent
histories interpretation of quantum mechanics based on primary and secondary
literature. Firstly, the formalism of the consistent histories approach will be
outlined.
  Secondly, the works by Robert Griffiths and Roland Omn\`es will be discussed.
Griffiths' seminal 1984 paper, the first physicist to have proposed a
consistent-histories interpretation of quantum mechanics, followed by Omn\`es'
1990 paper, were instrumental to the consistent-histories model based on
Boolean logic.
  Thirdly, Murray Gell-Mann and James Hartle's steps to their own version of
consistent-histories approach, motivated by a cosmological perspective, will
then be described and evaluated. Gell-Mann and Hartle understood that
spontaneous decoherence could path the way to a concrete physical model to
Griffiths' consistent histories.
  Moreover, the collective biography of these figures will be put in the
context of the role played by the Santa Fe Institute, co-founded by Gell-Mann
in 1984 in Santa Fe, New Mexico, where Hartle is also a member of the external
faculty.
