I introduce the metaphor of the ‘big epistemic grinder machine’ as an image to explain the mechanisms involved in theory change and the continuities and ruptures characteristic of this kind of change. I also provide an accurate epistemological evaluation of the results of its grinder mechanisms. One advantage of this model is that it brings the complex roles that different types of empirical successes and epistemic errors have in theory change into focus. The dynamic and diachronic interrelation of these successes and errors vulnerably provides increasing degrees of epistemic verisimilitude to our scientific theories. One of the main results of this metaphor is a place for the notion of truth that is neither inflationary nor deflationary. In this regard, I put forward the novel notion of ‘epistemic osmosis’. I then commend what it seems to be the most sensible epistemological attitude towards the outcomes of our scientific theories; namely, that of an epistemological agnosticism-cum-rational epistemic hope.