Do anthropic arguments really work?
  The anthropic explanation for the peculiarly small observed value of the
cosmological constant $\Lambda_{\rm obs}$ argues that this value promotes the
formation of stars, planets, and ultimately of observers such as ourselves. I
show that a recent analytic model of cosmic star formation predicts that
although $\Lambda_{\rm obs}$ maximises the overall efficiency of star formation
in the universe, the probability of generating observers peaks at $\sim400-500
\, \Lambda_{\rm obs}$. These preliminary results suggest that an immediate
connection between star formation efficiency and observers' generation is not
straightforward, and highlight the subtleties involved with the application of
anthropic reasoning.
