Pictures of space-time look misleadingly like pictures of space, and the novice must unlearn some of the conventions... - Tim Maudlin

[T]he most general question we can ask about matter is what sort of thing it is. ...[W]e might hold that matter is made of point-like particles, or of fields, or of one-dimensional strings, or of some combination of these, or of something else altogether. Given any of these ...there are further, more specific questions ...We will be concerned with the most general questions, rather than the more specific ones.

Fundamental conceptual changes occur, but they are always modifications of a previously existing structure. ...[T]actical adjustments are made in order to render the whole consistent. The ad hoc nature of this procedure may leave us with lingering doubts as to whether the whole really is consistent.

Metaphysics is ontology. Ontology is the most generic study of what exists. Evidence for what exists, at least in the physical world, is provided solely by empirical research. Hence the proper object of most metaphysics is the careful analysis of our best scientific theories (and especially of fundamental physical theories) with the goal of determining what they imply about the constitution of the physical world.