 Although ontology is often understood as the discipline that tries to find out what there is, or what exists, this is rejected by many in the contemporary debate. These philosophers think that the job of ontology is something different, and there is disagreement among them what it is more precisely. Among the proposed options are the projects of finding out what is real, or what is fundamental, or what the primary substances are, or what reality is like in itself, or something like this. Proponents of these approaches often find the questions about what there is too inconsequential and trivial to take them to be the questions for ontology. Whether there are numbers, say, is trivially answered in the affirmative, but whether numbers are real, or whether they are fundamental, or primary substances, etc., is the hard and ontological question. See (Fine 2009) and (Schaffer 2009) for two approaches along these lines. But such approaches have their own problems. For example, it is not clear whether the question whether numbers are real is any different than the question whether numbers exist. If one were to ask whether the Loch Ness monster is real, it would naturally be understood as just the same question as whether the Loch Ness monster exists. If it is supposed to be a different question, is this due to simple stipulation, or can we make the difference intelligible? Similarly, it is not clear whether the notion of what is fundamental can carry the intended metaphysical weight. After all, there is a perfectly clear sense in which prime numbers are more fundamental in arithmetic than even numbers, but this isn’t to hold the metaphysical priority of prime numbers over other numbers, but simply to hold that they are mathematically special among the numbers. Thus to ask whether numbers are fundamental is not easily seen as a metaphysical alternative to the approach to ontology that asks whether numbers exist. See (Hofweber 2009) and chapter 13 of (Hofweber 2016) for a critical discussion of some approaches to ontology that rely on notions of reality or fundamentality. Whether such approaches to ontology are correct is a controversial topic in the debate about ontology which we will not focus on here. However, this approach gives rise to a special connection between logic and ontology which we will discuss in the following.