the authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest .
 recent years have seen the emergence of an important new fundamental theory of brain function . 
 this theory brings information - theoretic , bayesian , neuroscientific , and machine learning approaches into a single framework whose overarching principle is the minimization of surprise ( or , equivalently , the maximization of expectation ) . 
 the most comprehensive such treatment is the  free - energy minimization  formulation due to karl friston ( see e.g. , friston and stephan , 2007 ; friston , 2010a , b  see also fiorillo , 2010 ; thornton , 2010 ) . 
 a recurrent puzzle raised by critics of these models is that biological systems do not seem to avoid surprises . 
 we do not simply seek a dark , unchanging chamber , and stay there . 
 this is the  dark - room problem .  here , we describe the problem and further unpack the issues to which it speaks . using the same format as the prolog of eddington s space , time , and gravitation ( eddington , 1920 ) we present our discussion as a conversation between : an information theorist ( thornton ) , a physicist ( friston ) , and a philosopher ( clark ) . 
Conflict of Interest Statement