I develop an informational conception of logic as a science fundamentally concerned not with truth but with information. Facts about logical validity, on this conception, tell us about the structure of the bodies of information that we generate, encounter, absorb, and exchange as we interact with one another and learn about our world. I also investigate the normative role of logic in our epistemic practices. In particular, I argue against the widespread idea that there are rational requirements to have logically coherent beliefs that are not merely epiphenomenal on evidential norms.

Deflationists have been hard at work convincing us that the concept of truth is far less interesting, and therefore far less mysterious, than long-lasting debates as to its true nature have made it seem. By denying that there is a substantive notion of truth expressed by our uses of the word `true,' deflationism promises to dissolve a number of explanatory hurdles.

Donald Davidson rejected deflationism. He grew increasingly sceptical of attempts to assimilate our understanding of truth to any definition or schema, and came to see his own approach to meaning as crucially dependent on a substantive notion of truth.

Exactly how, and where, does Davidson's approach to meaning depend on the availability of a substantive notion of truth? One of my goals is to answer this question. Another is to explain why it has proved so hard to answer it. A third goal is to bring to light what it would really be like to be a deflationist--in particular, what linguistic competence would look like if we took deflationism seriously.

In Chapter 1, I clarify Davidson's proposal to use truth theories as meaning theories. I explain this proposal as rooted in a certain conception of a meaning theory as an account of a speaker's understanding of her own sentences, and of this understanding as at least partly consisting in the speaker's knowledge of the truth-conditions of her sentences. In Chapter 2, I argue that deflationism does not allow us to describe competent speakers as knowing the truth-conditions of their sentences. If this is right, deflationism is incompatible with Davidson's conception of truth theories as theories of linguistic competence, but not for the reason usually given. That is, it is not because deflationism explains knowledge of truth-conditions as a trivial by-product of linguistic competence rather than being constitutive of it, since deflationism does not even allow us to ascribe such knowledge to speakers.

In Chapter 3, I argue against the widespread assumption that Davidson's proposal concerning the form to be taken by a meaning theory is primarily an answer to the question: what knowledge would enable us to interpret any utterance in a given language? This assumption underlies recent attempts to exhibit Davidson's approach to meaning as hospitable to a deflationary account of truth. However, as I explain, it undermines the distinction Davidson insists on between meaning theories and translation manuals, and thus cannot be right. Chapter 4 further argues that the methodology of radical interpretation does not, by itself, explain the need for a substantive notion of truth, contrary to what some (including Davidson) have suggested. Finally, in Chapter 5, I highlight some consequences of these results for both our understanding of Davidson's philosophy of language, and our understanding of deflationism.

Around 600BC, Epimenides, a Cretan apparently discontented with the

honesty of his compatriots, lamented that all Cretans are liars.

Together with a few innocent assumptions, well-entrenched principles

of logic entail that Epimenides' lamentation cannot be true, and yet

cannot be untrue---a flat contradiction. What's gone wrong? In this

dissertation, I argue that the source of the problem has been

misdiagnosed as one about language (especially formal languages). The

problem runs deeper, and stems from the structure of thought itself.

The dissertation proceeds in two main stages. The first stage

(Chapter 2) makes the case that that the intuitions that underlie the

paradoxes come from natural languages, not from formal/mathematical

ones. The Liar and related paradoxes are generally presented as

constraints on the latter. Their lesson, the story goes, is that no

formal theory strong enough to represent the primitive recursive

functions can include a satisfactory truth predicate. I argue that

it's our natural-language competence with the truth predicate that

underlies our understanding of what 'satisfactory' means here, which

shifts the focus of the project to natural language semantics. In this

domain, it's tempting to think (and many have thought) that the

problem with Epimenides' utterance is that it fails to express a

proposition, and this failure explains why we have trouble assigning

it a truth-value. Or, perhaps it does express a proposition, but not

the one that it seems to express. Or, perhaps it can express a

proposition, but which proposition it expresses depends on context. I

argue that all such responses fail, in part because they cannot make

sense of related attitude attributions. I can believe or disbelieve

Epimenides, which wouldn't be possible if his utterance didn't express

the proposition it seems to express.

In the second stage, I argue that such paradoxes arise, not from the

language/thought interface, but rather from thought itself. The first

step in this argument concerns knowledge attributions (Chapter 3),

where I develop and defend a novel solution to the Knower paradox.

Then I move from attitude attributions to attitudes themselves

(Chapter 4). Just as sentential truth and knowledge predicates gives

rise to paradoxical sentences, seemingly innocent combinations of

beliefs and desires give rise to paradoxical propositions---even when

those beliefs and desires are not expressed in language. The

possibility of such pathological combinations isn't accounted for by

any extant theory of mental content, and, I argue, provides support

for a non-classical theory. Finally (Chapter 5) I consider an

objection to these putative combinations of desires. I introduce what

I call /advisory/ desire reports, which seem to exhibit the radically

externalist behavior that the previous chapter rejects. I conclude by

offering reasons to think that the availability of these readings does

not undermine the case for non-classical accounts of attitudes.

At a fairly high level of abstraction, this work is about some ways in which questions about the correct treatment of the semantic paradoxes and questions about the principles of rationality governing doxastic states can be mutually illuminating.

In the first part of the dissertation, I argue that certain treatments of the semantic paradoxes lead to surprising conclusions about the nature of the doxastic states of rational agents. The semantic paradoxes, such as the liar paradox, provide us with good reason to take seriously various non-classical logics. In addition to the semantic paradoxes, there are also paradoxes that show that some extremely plausible principles of rationality governing doxastic states are inconsistent given classical logic. I show how various non-classical responses to the semantic paradoxes provide us with resources sufficient to resolve these paradoxes. In particular, if we allow that certain statements about an agent's doxastic state, e.g., statements about whether an agent believes a proposition P, may give rise to certain failures of classical logic, then we can hold on to all of our plausible principles of doxastic rationality. I use this fact to argue for the conditional claim that if one is inclined to reject classical logic in response to the liar paradox, then one should allow that statements about an agent's doxastic state may also give rise to failures of classical logic. Since the antecedent of the conditional is reasonable, and the consequent surprising, the conditional is of interest.

In the second part of the dissertation, I argue that attention to questions about the nature of doxastic rationality can provide us with important insights into the correct treatment of the semantic paradoxes. For any non-classical response to the semantic paradoxes, an important question that arises is: what exactly is the cognitive significance of the non-classical semantic statuses employed by the theory? I argue that our earlier reflections on the normative paradoxes show that the standard ways of answering this question are wrong. Given standard accounts of the cognitive significance of non-classical semantic statuses, we can resurrect our normative paradoxes. What this means is that the standard accounts of non-classical cognitive significance are in conflict with certain fundamental principles of doxastic rationality. I argue that in order to reconcile the account of non-classical cognitive significance with these principles we need to say that the correct rational response to paradoxical propositions, such as that expressed by the liar sentence, is for there to be a mirroring non-classicality in one's doxastic state. A rational agent, then, will be such that the claim that it believes the proposition expressed by the liar sentence will have the same non-classical status as the proposition expressed by the liar sentence. What emerges is a new picture of the significance of non-classical treatments of the semantic paradoxes.

The literature on demonstratives is largely built around two dogmas: (1) demonstratives are directly-referential and (2) demonstratives are context sensitive. (1) cannot be sustained in the face of data from English and other languages, and there are no compelling reasons for accepting (2). If we give up the dogmas and treat demonstratives as free variables that are interpreted with regard to a pragmatically-determined assignment function, we can explain a host of otherwise problematic data, and do so in a theoretically attractive way.

Formal developments of normative theories typically claim that the guidance they give is universal: for any agent, and any way the world could be, there is a way she is permitted (according to that theory) to act. Yet when we consider an agent facing an open, indeterminate future, cases are possible in which what is permitpted depends on what she actually does. These situations follow the letter of the law while seeming to violate its spirit. A famous example, discussed by Gibbard and Harper (1978), comes from Somerset Maugham: while in Damascus, you learn that Death is coming to collect your soul. Your one option is to flee to Aleppo. But you are confident that Death never misses her quarry: if you flee to Aleppo, Death will be there. But if you stay in Damascus, Death will be there too.

If Death is going to Damascus, you should go to Aleppo, and if Death is going to Aleppo, you should go to Damascus. So for any way the world could be, there is a way you should act. Yet there is a clear sense in which there is nothing you can do: since Death's destination depends on yours, no act is such that you ought to have done it, *given that you do it*. The norms of rationality in cases of this structure---and cases with the opposite structure, where available acts deontically validate themselves---are the subject of much recent work in ethics, decision theory, and the metaphysics of persons. I show how a model theory for the natural language modals Ought and May can incorporate these notions of deontic validation and self-defeat. Because May tracks the concept of permissibility brought out by act-dependent cases, its inferential properties reflect the language-*independent* intuitions we have about choiceworthiness, in cases like Death in Damascus.

This theorizing makes contact with natural language in the form of my solutions to two infamous puzzles about deontic modal language, free choice permission (Kamp 1973) and Ross's puzzle (Ross 1941). Free choice permission is the apparent validity of the classically *invalid* inference from May([phi] or [psi]) to both May[phi] and May[psi], and Ross's paradox is the apparent *in*-validity of the classically valid inference from Ought[phi] to Ought([phi] or [psi]). The first step to a unified solution to these puzzles is precisely to leverage the notion of permissibility corresponding to deontic self-validation. The second component is a generalization of classical logic. On my account, the interpretation of a disjunction depends on which of its atomic disjuncts are true at the actual state---where the 'actual state' can be keyed to the *future*-actual state an agent chooses when she acts. While classical consequence is preserved for sentences without modals, this analysis sets up a match between the act one brings about and the contents of statements describing that act's deontic status: for example, in futures where the agent chooses to [phi], it is [phi] that she has permission to do. This allows the stronger-than-classical conclusions of free choice permission to follow, and blocks the inference in Ross's puzzle. It also predicts the positive entailment properties of disjunction under Ought, while preserving the inviolability of the role classical disjunction plays in our reasoning. This intuitively appealing combination has, in previous work, proved difficult to achieve.

Few questions concerning the character of our talk about the world are more basic than how predicates combine with names to form truth-evaluable sentences. One particularly intriguing fact that any account of predication needs to make room for is that natural language allows for quantification into predicate position, through constructions like `She is everything one might hope to be: healthy, wealthy, and wise'. A natural and initially plausible view has it that predicates function to denote properties, and that such predicative quantifiers accordingly quantify over properties. This approach faces immediate difficulties, however.

After all, properties are objects of a certain sort, quantified over in nominally quantified sentences like `Steel has some properties aluminum lacks'. Indeed, properties seem precisely not to be what predicative quantifiers quantify over: although happy is something Oscar is, the property of being happy surely isn't. Further, if predicative quantifiers quantify over properties, they presumably carry ontological commitment to properties. But for it to be the case that there is something Oscar is, it suffices that he be happy, or morose, or loquacious. And surely the claim that Oscar is, say, loquacious does not commit us to properties. The vehicles for such commitment, it seems, are once again nominally quantified sentences like the one given above.

I begin by asking what a nominalist alternative to the property-based approach might look like, and proceed to develop what I term the Ockhamist Account on the nominalist's behalf. This Ockhamist Account, however, derives its primary appeal from the apparent shortcomings of the property-based view. The remainder of the dissertation investigates whether the problems that initially appear to beset the property-based view do indeed undermine it.

I argue that first worry mentioned above doesn't force us to deny that predicative quantifiers quantify over properties, but should rather lead us to recognize that an expression has semantically relevant features beyond what it denotes. In particular, I argue that we can explain the truth conditional difference between pairs like `Oscar is happy' and `Oscar is the property of being happy' by distinguishing the semantic relations predicative and nominal expressions bear to their semantic values: whereas nominal expressions like `the property of being happy' refer to properties, predicates express or ascribe them. This lets us construe the difference between predicative quantification and nominal quantification over properties not in terms of what is quantified over, but in terms of the semantic relation the bound variables bear to their values.

I next turn to substitution failures involving adjective nominalizations, like the one exhibited by `Wisdom is admirable' and `The property of being wise is admirable'. As I show, once we allow that the semantically relevant features of an expression aren't exhausted by what semantic value it has, we needn't take such cases to demonstrate that `wisdom' fails to have the property of being wise as its semantic value, any more than we need to deny that `happy' has the property of being happy as its semantic value.

The proposal also offers us a compelling response to the problem about ontological commitment. I argue that the objection conflates the question of whether a given quantifier quantifies over certain things with the question of whether the expressions into the position of which it quantifies refer to those things. The view I defend lets us disentangle these two issues, and shows that we can construe predicative quantifiers as quantifying over properties while still acknowledging that the expressions into the position of which they quantify fail to name, or refer to, those properties.

I conclude by considering the problem that Russell's Paradox poses for the property-based view. I canvas various strategies for responding to the threat of the paradox, but also register some reservations about each. I also offer some reasons for thinking that the Ockhamist Account is not entirely free from difficulties in this area, however. The problems raised by Russell's Paradox therefore point to the need for further refinement on both ends, rather than showing that one account must be abandoned in favor of the other.