  Our paper discusses the epistemic attitudes of particle physicists on the
discovery of the Higgs boson at the Large Hadron Collider (LHC). It is based on
questionnaires and interviews made shortly before and shortly after the
discovery in 2012. We show, to begin with, that the discovery of a Standard
Model (SM) Higgs boson was less expected than is sometimes assumed. Once the
new particle was shown to have properties consistent with SM expectations -
albeit with significant experimental uncertainties -, there was a broad
agreement that 'a' Higgs boson had been found. Physicists adopted a twopronged
strategy. On the one hand, they treated the particle as a SM Higgs boson and
tried to establish its properties with higher precision; on the other hand,
they searched for any hints of physics beyond the SM. This motivates our first
philosophical thesis: the Higgs discovery, being of fundamental importance and
establishing a new kind of particle, represented a crucial experiment if one
interprets this notion in an appropriate sense. By embedding the LHC into
thetradition of previous precision experiments and the experimental strategies
thus established, Duhemian underdetermination is kept at bay. Second, our case
study suggests that criteria of theory (or model) preference should be
understood as epistemic and pragmatic values that have to be weighed in factual
research practice. The Higgs discovery led to a shift from pragmatic to
epistemic values as regards the mechanisms of electroweak symmetry breaking.
Complex criteria, such as naturalness, combine epistemic and pragmatic values,
but are coherently applied by the community.
