De Dicto Propositions Are Grounded in Concepts and De Re Propositions Are Grounded in Objects

On the contrary, Forbes' In Defense of Absolute Essentialism: Necessary propositions of a de dicto form are necessary on account of de re facts about the objects which are constituents in the proposition - namely, the subject and predicates. So de re modality is fundamental, but de dicto is not therefore ranging over merely statements, rather it expresses de re modality in a different manner. Forbes states, "...even in simple de dicto neccesities, the source of the necessity is to be found in the properties to which the predicates of the de dicto truth refer" and, accordingly, "I deny that the source of de dicto necessity is in concepts."

I reply, though we may speak of the "properties" of the square and of right angles being the ground for such a de dicto truth, these are not objects and they are neither actual nor existents - they are objects and properties merely in conceptu. For any particular square, it is true, it will have right angles as a result of its own particular nature and its de re character. But this does not change the fact that the necessity of the proposition 'a square has right angles' is grounded in the concepts 'square' and 'right angle', not in any particular square or any particular right angles - and therefore, not in a de re fashion. This is why Leibniz stated in a letter to von Hessen-Rheinfels that "...we must philosophize differently about the notion of an individual substance than we do about the specific notion of a sphere".

On the other hand, perhaps it is the case that de re statements just are expressions of de dicto statements and therefore all modality is founded in conceptu. For a property P to be necessary to an object x just is for the proposition "if x has a certain set S of properties, x will have P" to be logically necessary. So, in the end, modality in the end is founded in and depends on dicta.

I reply that though such entailments might express necessary statements of de dicto modality, this does nothing to reduce de re modality. For this de dicto truth is truly founded in the de re character of the objects in question. S entailing P necessarily speaks of the modal character of the properties of S and the nature of x. For x must be such that it is able to posses all of the properties which are members of S and each property in S must be capable of being compresent with the others. There is then de re modality in both of these aspects - since presumably not all objects that have S will have to have P and not all properties are compossible with one another. These de re truths might have some de dicto translation but it is, at any rate, secondary and supervenient with respect to them.