Abstract
The investigation presented here addresses two central points, which are independent but complement each other. First, there is the issue of quantities. This subject has been discussed in the philosophical literature from different angles and, most prominently, from the question of what quantities are. The answers to this question have widely varied, but each has reached little consensus. This fact motivates the need for a different analysis: as argued throughout this work, a promising option is via the question of what grounds quantity facts. At this moment, the second point comes into play—it addresses the metaphysical relation of grounding. The analysis of questions of the form what grounds what requires an adequately transparent notion of grounding. To this extent, the present proposal suggests understanding grounding from a model extracted from the relation between a mathematical structure and its basis.