Joseph Owens in The Interpretation of Existence approaches the fact of existence, proceeding from common viewpoints to discover its meaning as more than fact. Concepts alone do not signify existence, nor do the multiplication of concepts. To understand existence (esse) one must compose a sentence, that is, a proposition. The proposition "whooping cranes exist", unlike mere categorical attribution, asserts the existence of its subject. This proposition is accepted "as true or rejected as false on the basis of what one knows through looking at the actual situation, through observing or concluding to what is there in the actual world." In this way, we tacitly acknowledge, admit that we possess the means to know that the thing actually exists. A fact of existence is thereby synthetic in its ability to be grasped by the mind and thus presumes "a type of intellectual activity that is correspondingly synthetic in its very nature as a cognitive function."
The proposition then expresses "a type of knowledge that the intellect is able to attain about its objects, a type of knowledge that cannot be expressed in a concept or communicated in English by a single word. It is a type of knowledge that can only be mentally expressed in the synthesis of a proposition and communicated verbally in a sentence." Concepts alone cannot give us existence. "Just as the substance of a thing and the color of a thing and its relations and other categorical units are grasped by the intellect through conceptualization, so the thing's existence is indeed grasped intellectually, but not through conceptualization, at least not originally. The apprehension of existence requires a different kind of intellectual activity" (19-21).
What is that kind of intellectual activity? It is not based just upon conceptualization. The facts of existence have led us to it.
And so the fact of existence is the starting point.