Abstract

There is a significant difference between the words `is' and `exists' that has either been overlooked or under-appreciated by many philosophers. This difference comes in sentences that express existential quantification using `is', `exists', or their cognates, such as, "There are cookies in the jar," or, "There exists a strange species of fish that nobody has studied yet." Phrases such as `there are' and `there exists' are existential quantifier expressions, since they're used to express existential quantification. The orthodox view of these expressions is that they are, in the words of David K. Lewis, "entirely synonymous and interchangeable". This dissertation presents and argues for an anti-orthodox view of meaning of `there is' and `there exists'. The root of the difference in meaning between the two expressions is that `there is' turns out to be context-sensitive, on the model of demonstratives like `this' or `that', while `there exists' is invariant in its meaning. These views are motivated through the introduction of a notion called `ontological robustness', which helps us evaluate the level of ontological commitment in our assertions. The anti-orthodox view is defended over orthodoxy through holistic arguments that compare the virtues of each theory, including such metrics as how they fare in accounting for our stubborn desire to talk about and quantify over nonexistent objects.