Nick Tosh (NUI Galway) gives a talk at the MCMP Colloquium (2 December, 2015) titled "Ensemble Realism. A new Approach to Statistical Mechanical Probability". Abstract: “What we know about a body can generally be described most accurately and most simply by saying that it is one taken at random from a great number (ensemble) of bodies which are completely described.” So wrote Willard Gibbs in 1902, but with his fingers crossed, for he regarded ensembles as convenient fictions. A century later, they are still convenient, and we still have no settled account of the literal meaning of statistical mechanical probability assignments. My aim is to show how talk of ensembles might be taken seriously.