Hume's sceptical arguments regarding induction have not yet been successfully answered. However, I shall not in this paper discuss the important attempts to answer Hume since that would be too lengthy a task. On the supposition that Hume's sceptical arguments have not been met, the empirical world is a place where, as the popular metaphor goes, all the glue has been removed. For the Humean sceptic, the only empirical knowledge that we can have is given to us in immediate perception. We have no reason to believe that the patterns of future events will in any way resemble patterns of events in the present or past. We have no reason to believe even that present events not observed resemble present events that are observed, or that knowledge of past and present can be any guide in making new discoveries about what took place in the past. What we have is an ideal setting for the calculation of a priori probabilities. We have a field of distinct events having no logical or evidential ties to one another. The attempt to justify induction that I wish to present is an appeal to a priori probability.