De dicto andde re are two phrases used to mark a distinction inintensional statements, associated with the intensional operators in many such statements. The distinction is used regularly in analyticalmetaphysics and inphilosophy of language.[1]
The literal translation of the phrasede dicto is "about what is said",[2] whereasde re translates as "about the thing".[3] The original meaning of the Latin locutions may help to elucidate the living meaning of the phrases, in the distinctions they mark. The distinction can be understood by examples of intensional contexts of which three are considered here: a context of thought, a context of desire, and a context ofmodality.
There are two possible interpretations of the sentence "Peter believes someone is out to get him":
On thede dicto 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 predication 'someone is out to get Peter' is satisfied.
On thede 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-contradictory beliefs.[4] SayLois Lane believesClark Kent is weaker thanSuperman. Since Clark Kent is Superman, takende 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. Understoodde dicto, however, this may be a perfectly reasonable belief, since Lois is not aware that Clark and Superman are one and the same.
Consider the sentence "Jana wants to marry the tallest man in Fulsom County". It could be read eitherde dicto orde re; the meanings would be different. One interpretation is that Jana wants to marry the tallest man in Fulsom County, whoever he might be. On this interpretation, what the statement tells us is that Jana has a certain unspecific desire; what she desires is forJana is marrying the tallest man in Fulsom County to be true. 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 Fulsom County. Her desire is forthat man, and she desires herself to marryhim. The first interpretation is thede dicto interpretation, because Jana's desire relates to the words "the tallest man in Fulsom County", and the second interpretation is thede re interpretation, because Jana's desire relates to the man those words refer to.
Another way to understand the distinction is to ask what Jana would want if a nine-foot-tall immigrant moved to Fulsom county. If she continued to want to marry the same man – and perceived this as representing no change in her desires – then she could be taken to have meant the original statement in ade re sense. If she no longer wanted to marry that man but instead wanted to marry the new tallest man in Fulsom County, and saw this as a continuation of her earlier desire, then she meant the original statement in ade dicto sense.
The number of discoveredchemical elements is 118. Take the sentence "The number of chemical elements is necessarily greater than 100". Again, there are two interpretations as per thede dicto/de re distinction.
Another example: "ThePresident of the US in 2001 could not have beenAl Gore".
Inmodal logic the distinction betweende dicto andde re is one ofscope. Inde dicto claims, any existentialquantifiers are within the scope of the modal operator, whereas inde re claims the modal operator falls within the scope of the existential quantifier. For example:
| De dicto: | Necessarily, somex is such that it isA | |
| De re: | Somex is such that it is necessarilyA |
Generally speaking, islogically equivalent to, both meaning that allx in all the possible worlds areA (assuming that therange of quantification/domain of discourse is the same in all the accessible possible worlds); However, means that each accessible possible world has its ownx that isA, but they are not necessarily the same, whereas means that there is a specialx that isA in all accessible possible worlds.
Similarly, is logically equivalent to, both meaning that in some accessible possible world, there is somex that isA; However, means that in some accessible possible world, allx areA, whereas means that for eachx in therange of quantification/domain of discourse, there is some accessible possible world wherex isA, but it can be true that no world has twox that are bothA.