  Standard chemical evolution models based on long-term infall are affected by
a number of problems, evidenced by the analysis of the most recent data. Among
these: (1) models rely on the local metallicity distribution, assuming its
shape is valid for the entire Galaxy, which it is not; (2) they assume that the
solar vicinity abundance patterns resulted from a unique chemical evolution,
which it does not; (3) they assume the disk is a single structure with chemical
properties that are a smooth function of the distance to the galactic center,
which it is not. Moreover, new results point to a thick disk being as massive
as the thin disk, leading to a change of paradigm in the way we see the
formation of these structures. I discuss these various issues, and, commenting
on Snaith et al. (2014), how a closed box model offers an interesting
approximation to the galactic chemical evolution, by providing the conditions
in which large amounts of gas are available in the disk at high redshift. The
novel way presented in Snaith et al. (2014) to derive SFH from stellar
abundances is also discussed, providing a measurement of the SFH of old
populations that is valid for the entire Galaxy. The derived SFH shows that the
formation of the thick disk has been the dominant epoch of star formation in
our Galaxy.

Astrophysics of Galaxies