In ordinary writing people are not fussy about quotation marks. A printed sentence may read, “The word red has three letters”. Logicians and philosophers of language may shudder at such violations of the rules of use and mention, but most people take them in stride. It is not that they are blind to the distinction; they just think it pedantic to insist on adding quotation marks. The same is true for speech: people don’t generally insert explicit quotation indicators in their spoken references to words; they don’t say, “The word, quote, ‘red’, unquote, has three letters”. They often leave the apparatus of quotation implicit, leaving it to the reader or hearer to supply it—and the context is generally sufficient to make it clear that a mention of a bit of language is intended. We can then pedantically step in to make the quotation explicit, thus rendering the true logical form clear. We make explicit what was implicit—we supply a linguistic analysis. That is, there is a good deal of implicit quotation in ordinary language, written and spoken. It is true that confusions can arise because of such sloppiness, and so it is useful to be on the lookout for covert quotation. In an ideal language all quotation would no doubt be explicitly signposted.
How widespread is implicit quotation? Is there perhaps a lot more of it than we realize? Consider this exchange: “I met a man last night, named Jack, who said he was a philosopher”; “This man, Jack, was he interesting?” The trained philosopher of language will spot the missing quotation marks in the first sentence—it should be “named ‘Jack’”, she will insist. But surely much the same should be said about the second sentence: it should really read, “This man, the one named ‘Jack’, was he interesting?” Or consider a baptism ceremony in which these words are pronounced, “I baptize you Seth. Now Seth, live long and prosper”. Clearly the first “Seth” should be in quotation marks, but couldn’t the second occurrence be aptly paraphrased as “child named ‘Seth’”? What about the sentence, “Hi, I’m John—I’m a philosopher”: doesn’t this mean, “Hi, my name is ‘John’—I’m a philosopher”? Notice how the aptness of the paraphrase for the first part of the sentence doesn’t carry over to the second part: it would not do to paraphrase that part as, “I’m called a ‘philosopher’” or “I’m described as a ‘philosopher’” or “I satisfy the predicate ‘philosopher’”. Here the word “philosopher” really is used not mentioned. Another example: “Roses are red”—how can it be paraphrased? We can naturally say, “The flowers called ‘roses’ are red”, but we cannot naturally say, “Roses are called ‘red’”. That is because “rose” is a name for a certain type of flower, but “red” is not a name of anything—it is a descriptive adjective. Nor do we say “Roses have the relation called “are” to the color red”.
This suggests a hypothesis: all occurrences of names in natural languages implicitly involve quotation. The hypothesis can be applied both to proper names and common names: names of people, places, countries, etc., and names of animal species, chemical kinds, types of drug, etc. That is, we can correctly paraphrase any occurrence of a name that occurs without quotation marks by inserting quotation marks and adding a semantic predicate like “called” or “named”. Thus, “Tabby is a cat” can be paraphrased as, “The animal called ‘Tabby’ belongs to the species called ‘cat’”. We can do this because all uses of names involve implicit quotation. And the intuitive reason for this is simply that names are not descriptive: they are mere labels we stick on things to enable us to pick them out. It is quite otherwise with other words—quantifiers, connectives, predicates of color and shape. These are not names that we attach to things, mere empty labels; they supply substantive concepts—in a clear sense they have meaning. But a name is really meaningless, just a label or tag—that’s the point of name. You don’t learn anything about a person or place just by learning his or its name—all you learn is what we choose to call the person or place in question. But you learn a lot about a person or place by being told his or its size, shape, color, etc.—here you learn objective facts, not linguistic practices. There is a clear difference between names and other bits of language; and that difference is reflected in the fact that names always implicitly involve quotation. 
Names are rather like those numbers you get assigned at the DMV and elsewhere, which function as temporary labels: for the nonce you are labeled, say, 67. There is no descriptive information in that number (it doesn’t correspond to your height or weight)—it is merely a convenient tag. If you say “I am 67” you make no descriptive statement; you simply state what number has been assigned to you. If an official says, “67 is disqualified”, that statement is aptly paraphrased as, “the person assigned the number 67 is disqualified”: the official refers to the number and uses an assignment predicate—as we refer to a name and use a semantic predicate. We could just as well say, “the person assigned the name ‘John Smith’” instead of simply “John Smith”. In the number assignment case we can easily see how the true logical form might become covert: instead of always saying “the person assigned the number N” speakers of the DMV dialect might abbreviate this to simply “N”—as in “67 is disqualified”. That is essentially what we do with names: we abbreviate—hence implicit quotation.
If our hypothesis is correct, then names also function self-referentially in identity statements: “a = b” means “the designation of ‘a’ = the designation of ‘b’”. This implies that “a” and “b” have different meanings, since the analysis involves reference to two different entities—the names “a” and “b”. Thus we can solve Frege’s problem of informative identities: the names are not distinguished by their reference, nor by some supposed “mode of presentation” of that reference, but by themselves as names. What we learn when we learn that a = b is just that the name “a” refers to the same thing as the name “b”, i.e. that what we call by those two names is the same thing. The case is just like the assigned numbers case: one person may be assigned two different numbers on two different days, so that we can write down the identity sentence “67 = 102”. What this means, when made explicit, is “the person assigned 67 = the person assigned 102”. We don’t need to bring in anything beyond the conventional assignment, such as modes of presentation. Whenever one of these number names occurs it can be translated using “the person assigned number N”. In the case of ordinary proper names the translation is, “the person assigned name N”. We learn something meta-linguistic when we learn that Hesperus is Phosphorus, though the superficial form of the sentence is not meta-linguistic. Perhaps the ease of this solution to Frege’s problem confirms the general correctness of the hypothesis: for that solution follows naturally from the hypothesis.
There has been much discussion about whether names are “directly referential”. According to the present analysis, the answer is that they are in one way but not in another. The name “a” is equivalent to a definite description “the denotation of ‘a’”, so it is no more directly referential of the bearer of the name than other descriptions. But the description embeds a quotation name of a name—and this name is directly referential. That is, the name directly refers to itself: the proposition expressed by a sentence containing the name thus contains the name (not an individual concept of the name). Names refer to themselves, and they do so directly: the name is part of its own meaning (along with the appended semantic predicate). The name names itself, and the name enters its own meaning. Again, the case is like the number labels: the phrase “the person assigned 67” contains a direct reference to the number 67, though it is not itself a directly referential term (it could be analyzed according to Russell’s theory of descriptions). The propositions expressed by sentences containing names are about names (not so for other words), and those names are constituents of the propositions expressed. Names are accordingly both directly referential and descriptive.
 It might be wondered whether it is possible in principle for implicit quotation to be more widespread: could a language be completely quotational? The answer is no: a sentence consisting only of quoted expressions is not a sentence but a list (at best). The most we can expect is something along these lines: “The denotation of ‘John’ stands in the relation expressed by ‘loves’ to the denotation of ‘Mary’” for “John loves Mary”. Language is essentially non-quotational in its basic nature. Still, there might be a lot more quotation that we generally recognize.