Not all truths are on a par. The realm of truths is structured: some
propositions are only true because others are. The relation that endows
the realm of truths with this structure is often called grounding.
Grounding has achieved much attention in 21st century metaphysics, but
the topic is arguably as old as philosophy itself. This becomes apparent
when investigating the works of the 19th-century philosopher Bernard
Bolzano, who developed what is perhaps the first comprehensive theory of
grounding, drawing on a rich tradition that goes back to Aristotle's
Posterior Analytics. Roski's book provides, for the first time, a
comprehensive study of Bolzano's theory of grounding in its entirety,
paying more attention than previous studies to the interaction between
grounding and the consequence-relation of deducibility.