 So where does all this leave us? The consensus seems to be that, while it is easy in specific examples to conclude that incomplete paths of various sorts represent singular structure, no entirely satisfactory, strict definition of singular structure in their terms has yet been formulated (Joshi 2014). As we will see in  section 1.4  below, moreover, spacetimes can evince entirely different kinds of behavior that manifestly are singular in an important sense, and yet which are independent of path incompleteness. For a philosopher, the issues offer deep and rich veins for those contemplating, among other matters, the role of explanatory power in the determination of the adequacy of physical theories, the role of metaphysics and intuition in the same, questions about the nature of the existence attributable to physical entities in spacetime and to spacetime itself, and the status of mathematical models of physical systems in the determination of our understanding of those systems as opposed to the mere representation of our knowledge of them. All of these issues will be touched upon in the following. 