De dicto and de re
De dicto and de re are two phrases used to mark important distinctions in intensional statements, associated with the intensional operators in many such statements. The distinctions are most recognized in philosophy of language and metaphysics.
The literal translation of the phrase "de dicto" is "of (the) word", whereas de re translates to "of (the) thing". The original meaning of the Latin locutions is useful for understanding the living meaning of the phrases, in the distinctions they mark. The distinction is best understood by examples of intensional contexts of which we will consider three: a context of thought, a context of desire, and a context of modality.
Context of thought
There are two possible interpretations of the sentence “Peter believes someone is out to get him”. On one interpretation, ‘someone’ is unspecific and Peter suffers a general paranoia; he believes that it is true that a person is out to get him, but does not necessarily have any beliefs about who this person may be. What Peter believes is that the predicate ‘is out to get Peter’ is satisfied. This is the de dicto interpretation.
On the de re interpretation, ‘someone’ is specific, picking out some particular individual. There is some person Peter has in mind, and Peter believes that person is out to get him.
In the context of thought, the distinction helps us explain how people can hold seemingly self-contradicting beliefs. Say Lois Lane believes Clark Kent is weaker than Superman. Since Clark Kent is Superman, taken de re, Lois’s belief is untenable; the names ‘Clark Kent’ and ‘Superman’ pick out an individual in the world, and a person (or super-person) cannot be stronger than himself. Understood de dicto, however, this may be a perfectly reasonable belief, since Lois is not aware that Clark and Superman are one and the same.
Context of desire
Consider the sentence "Jana wants to marry the tallest man in California". There are two ways to interpret this sentence (in the context of the de re - de dicto discussion). One interpretation is that Jana wants to marry the tallest man in California, whoever he might be. On this interpretation, what the statement tells us is that Jana has a certain unspecific desire; what she desires is that a certain situation should obtain, namely, Jana's marrying the tallest man in California. The desire is directed at that situation, regardless of how it is to be achieved. The other interpretation is that Jana wants to marry a certain man, who in fact happens to be the tallest man in California. Her desire is for that man, and she desires herself to marry him. Again, the first interpretation, "Jana desires that she marry the tallest man in California", is the de dicto interpretation. The second interpretation, "Of the tallest man in California, Jana desires that she marry him", is the de re interpretation.
Another way to understand the distinction is to ask what Jana would want if the man who was the tallest man in California at the time the original statement was made were to lose his legs, such that he was no longer the tallest man in California. If she continued to want to marry that man – and, importantly, perceived this as representing no change in her desires – then she could be taken to have meant the original statement in a de re sense. If she no longer wanted to marry that man but instead wanted to marry the new tallest man in California, and saw this as a continuation of her earlier desire, then she meant the original statement in a de dicto sense.
Context of modality
The number of discovered chemical elements is 117. Take the sentence "The number of chemical elements is necessarily greater than 100". Again, there are two interpretations as per the de dicto / de re distinction. The first interpretation is that things could not have gone differently, with the number of elements fewer than 100. Intuitively, this claim is false, because we know that if the inner workings of the atom were different, there could be fewer than 100 elements. The second interpretation is that things could not have gone differently with the number 117 turning out to be fewer than 100. Intuitively, this claim is true. Of all the ways the world could have turned out, presumably there are no possibilities wherein 117 is fewer than 100. That 117 is greater than 100 is a necessary fact. The first interpretation, which seems to yield a false statement, is the de dicto interpretation. The second interpretation, which seems to yield a true statement, is the de re interpretation.
Another example: "The President of the USA in 2001 could not have been Al Gore". This claim seems false on a de dicto reading. Presumably, things could have gone differently, with the Supreme Court not claiming that Bush had won the election. But it looks more plausible on a de re reading. After all, we might skeptically wonder of George W. Bush whether he could have been Al Gore. Indeed, assuming that being George Bush is an essential feature of George Bush and that this feature is incompatible with being Al Gore, a de re reading of the statement is true.
Representing de dicto and de re in modal logic
In modal logic the distinction between de dicto and de re is one of scope. In de dicto claims, any quantifiers are within the scope of the modal operator, whereas in de re claims the modal operator falls within the scope of the quantifier. For example:
| De dicto: | Necessarily, some x is such that it is A | |
| De re: | Some x is such that it is necessarily A |
