  The full causal M\"uller-Israel-Stewart (MIS) theory of dissipative processes
in relativistic fluids is applied to a flat, homogeneous and isotropic universe
with bulk viscosity. It is clarified in which sense the so called truncated
version is a reasonable limiting case of the full theory. The possibility of
bulk viscosity driven inflationary solutions of the full theory is discussed.
As long as the particle number is conserved almost all these solutions exhibit
an exponential increase of the temperature. Assuming that the bulk viscous
pressure of the MIS theory may also be interpreted as an effective description
for particle production processes, the thermodynamical behaviour of the
Universe changes considerably. In the latter case the temperature increases at
a lower rate or may remain constant during a hypothetical de Sitter stage,
accompanied by a substantial growth of the comoving entropy.
