This paper considers a form of scepticism according to which sentences, along with other linguistic entities such as verbs and phonemes, etc., are never realized. If, whenever a conversational participant produces some noise or other, they and all other participants assume that a specific sentence has been realized (or, more colloquially, spoken), communication will be fluent whether or not the shared assumption is correct. That communication takes place is therefore, one might think, no ground for assuming that sentences are realized during a typical conversation. I reject both this ‘folie-a-deux’ view and the arguments for it due to Georges Rey. I do so by drawing on Gilbert Harrnan’s no-false-lemmas principle. Since testimony is a form of knowledge and, according to the principle, knowledge cannot depend essentially on false assumptions, testimony is incompatible with the claim that sentence realization is but an illusion. Much of the paper is given over to defending this appeal to the no-false-lemmas principle. After all, a more attractive option might seem to be to infer instead that the principle is itself falsified by the folie-a-deux view.

This paper defends the commonsense conception of linguistic competence according to which linguistic competence involves propositional knowledge of language. More specifically, the paper defends three propositions challenged by Devitt in his Ignorance af Language. First, Chomskian linguists were right to embrace this commonsense conception of linguistic cornpetence. Second, the grammars that these linguists propose make a substantive claim about the computational processes that are presumed to constitute a speaker’s linguistic competence. Third, Chomskian linguistics is indeed a subfield of psychology, in the business of characterizing the linguistic competence of speakers.

Is knowledge of language a kind of knowledge-that or knowledge-how? Michael Devitt’s Ignorance of Language argues that knowledge of language is a kind of knowledge-how. Devitt’s account of knowledge of language is embedded in a more general account of the nature of language as grounded in thought. The paper argues that Devitt’s view is inconsistent when thought is understood in an externalist or anti-individualist way. A key phenomenon in externalist thought experiments is the possibility of incomplete or mistaken understanding, and its correction. This phenomenon is exhibited in our knowledge of language. Expanding on some brief remarks by Chomsky, it is argued that speakers display incomplete understanding in making mistakes in linguistic judgrnents. These mistakes can be irnproved through reflection on cases. In this process of mistake, reflection, and correction, speakers’ knowledge of language remains stable despite the change in linguistic judgments. This stable knowledge of language cannot be understood as kind of knowledge-how, without making the rational efficacy of reflection a constitutive feature of knowledge-how. But to do this is to obliterate the distinction between knowledge-how and knowledge-that. The conclusion is that if externalism about thought is accepted, then the knowledge in language is a kind of knowledge-that.

In Devitt’s view, linguistic intuitions are opinions about linguistic production of products, most often one’s own. They result frorn ordinary empirical investigation, so “they are immediate and fairly unreflectiveernpirical central-processor responses to linguistic phenomena”, which reactions are, moreover, theory-laden, where the ‘theory’ encompasses all sorts of speaker’s beliefs. The paper reconstructs his arguments, places his view on a map of alternative approaches to intuitions, and offers a defense of a minimalistic “voice-of-competence” view. First, intuitions are to be identified with the data, the minimal “products” of tentative linguistic production of naïve speaker-listeners, and not with their opinions about the data. Second, the data involve no theory and very little prototheory. Third, although there might be admixtures of guesswork in the conscious production of data, these are routinely weaned out by linguists. Finally, mere acceptance of the “voice of competence” does not land us in any objectionable Cartesianism: it is cornpatible with naturalism and with distrust of a priori philosophy.

My contribution takes up a set of methodological and philosophical issues in linguistics that have recently occupied the work of Devitt and Rey. Devitt construes the theories of generative linguistics as being about an external linguistic reality of utterances, inscriptions, etc.; that is, Devitt rejects the ‘psychologistic’ construal of linguistics. On Rey’s conception, linguistics concerns the mental contents of speaker / hearers; there are no external linguistic items at all. I reject both views. Against Devitt, I argue that the philosophical issues in linguistics should be framed in terms of the theories themselves, not pre-theoretical conceptions front either philosophy or commonsense as to what linguistics is about or what a language is. In this light, I suggest that Devitt’s key arguments (concerning parameter setting, psychological reality, and the role of intuitions) do not make sense of current linguistic inquiry and so do not offer an adequate philosophical basis of that work. To this extent, I agree with Rey. Ourdifferences emerge over the putative role of content in linguistic inquiry and how the concept of computation ought to be understood. Following the lead of Chomsky’s recent philosophical remarks, I argue that a theory of the language faculty should be understood as an abstract specification of the function that pairs ‘sound’ with ‘meaning’ rather than as a specification of the content the mind represents. But doesn’t ‘computation’ presuppose ‘representation’? I argue for a negative answer, at least if ‘representation’ is read intentionally. A ‘representation’ can be construed as brain structure that, at the present stage of inquiry, can only be picked out via the abstract concepts of linguistic theory. We are entitled to posit such structures insofar as they earn their explanatory keep over the output of the faculty. The linguistic function is a way of setting the boundary conditions on what the brain must be doing such that humans get to be competent speaker / hearers, although we do not therefore take the function to be a story of the causal spring of linguistic performance.

In his latest book, Michael Devitt rejects Chomsky’s mentalist conception of linguistics. The case against Chomsky is based on two principal claims. First, that we can separate the study of linguistic competence from the study of its outputs: only the latter belongs to linguistic inquiry. Second, Chomsky’s account of a speaker’s competence as consisiting in the mental representation of rules of a grammar for his language is mistaken. I shall argue, first, that Devitt fails to make a case for separating the study of outputs from the study of competence, and second, that Devitt mis-characterises Chomsky’s account of competence, and so his objections miss their target. Chomsky’s own views come close to a denial that speaker’s have knowledge of their language. But a satisfactory account of what speakers are able to do will need to ascribe them linguistic knowledge that they use to speak and understand. I shall explore a conception of speaker’s knowledge of language that confirrns Chomsky’s mentalist view of linguistics but which is immune to Devitt’s criticism.

Elsewhere I have argued that standard theories of linguistic competence are committed to taking seriously talk of “representations of” standard linguistic entities (“SLEs”), such as NPs, VPs, morphemes, phonemes, syntactic and phonetic features. However, it is very doubtful there are tokens of these “things” in space and time. Moreover, even if were, their existence would be completely inessential to the needs of either communication or serious linguistic theory. Their existence is an illusion: an extremely stable perceptual state we regularly enter as a result of being stimulated by the wave forms we regularly produce when we execute our intentions to utter such tokens (a view I call “Folieism”). In his Ignorance of Language, Michael Devitt objects to this view, arguing that, “On Rey’s view, communication seems to rest on miraculous guesses.” I argue here that my view is not prey to his objections, and actually affords a scientifically more plausible view than his “empiricist” alternative. Specifically, I reply to his objections that my view couldn’t explain the conventionality of language and success of communication (§2.1), that I am faced with intractable difficulties surrounding the identity of intentional inexistents (§2.2), and that, contrary to my view, SLEs can be relationally defined (§2.3). Not only can Folieism survive Devitt’s objections, but (§3) it also provides a more satisfactory account of the role of linguistic intuitions than the “empirical” account on which he insists.

This paper concerns the role of intuitions in mathematics, where intuitions are meant in the Kantian sense, i.e. the “seeing” of mathematical ideas by means of pictures, diagrams, thought experiments, etc.. The main problem discussed here is whether Platonistic argumentation, according to which some pictures can be considered as proofs (or parts of proofs) of some mathematical facts, is convincing and consistent. As a starting point, I discuss James Robert Brown’s recent book Philosophy of Mathematics, in particular, his primarily examples and analogies. I then consider some alternatives and counterarguments, namely John Norton’s opposite view, that intuitions are just pictorially represented logical arguments and are superfluous; and the Kantian transcendental theory of construction in imagination, as it is developed in the works of Marcus Giaquinto and Michael Friedman. Although I support the claim that some intuitions are essential in mathematical justification, I argue that a Platonistic approach to intuitions is partial and one should go further than a Platonist in explaining how some intuitions can deliver new mathematical knowledge.

Most disciplines make use of thought experiments, but physics and philosophy lead the pack with heavy dependence upon them. Often this is for conceptual clarification, but occasionally they provide real theoretical advances. In spite of their importance, however, thought experirnents have received rather little attention as a topic in their own right until recently. The situation has improved in the past few years, but a mere generation ago the entire published literature on thought experiments could have been mastered in a long weekend. Now the subject is beginning to flourish. Given the relative newness of the field, it might be useful to have several examples at one’s finger tips, so a number of great ones will be described. Attention will also be drawn outside physics and philosophy. In mathematics there is something analogous to thought experiments -- visual reasoning and picture proofs. I will look briefly at this class of thought experiments and try using them to make a case for possibly settling the continuum hypothesis. After this, I will return to thought experiments in the sciences and propose an account of how they work. Finally, I will end with a sketch of a topic I am currently working on, a kind of progress report which, I hope, will be an inducement to others.

In one of the most influential empiricist account on the epistemic nature of thought experiments John Norton proposes a challenge: that no thought experirnent in science could be found that cannot be logically reconstructed as an argument. Norton’s account has two main theses, the epistemic thesis that all information about the physical world delivered through a thought experiment comes solely frorn experience and the reconstruction thesis that all thought experiments could be reconstructed as arguments. In the present paper I argue that in at least sorne cases Norton’s theses are incompatible with each other and therefore their combination could not form a reliable account. I try to show that sometimes the experience available could not justify the conclusion of a thought experiment and even contradicts it. I suggest an analysis of Einstein’s Train Thought Experiment as a counterexample to the challenge.

Recent debates about thought experiments have focused on a perceived epistemological problem: how do thought experiments manage to provide knowledge when they yield no new empirical data? A bold answer to this question is provided by James Robert Brown’s platonisrn, according to which a certain class of thought experiments allow a sort of intellectual perception of laws of nature, understood as relations between universals. I suggest that there are three main problems with platonism. First, it is restricted to a very small class of thought experiments; hence, it largely fails to address the general epistemological problem. Second, it is not quite clear what it is supposed to explain. Third, its explanatory value in any case seems dubious, since the mechanisms it postulates (i) appear to raise issues more ditficult than what they would explain, and (ii) seem to obviate the very need for conducting thought experiments. I also argue that it fails to give an accurate account of Brown’s flagship example, Galileo’s thought experiment on falling bodies. In conclusion, I suggest that although platonism about thought experiments is an exciting thesis, it is at present unconvincing.

I explore the possibility that there are interesting and illuminating paralleIs to be drawn between issues central to the philosophical literature on scientific thought experiments (TE’s) and issues central to the phlilosophical literature on standard fictional narratives. I examine three related questions: (a) To what extent are TE’s (like) standard fictional narratives? (b) Is the understanding of TE’s like the understanding of standard fictional narratives? (c) Most significantly, are there illuminating paralIeIs to be drawn between the ‘epistemological problem’ of TE’s in science, and epistemological problems that attend some of the cognitive claims made for standard works of fiction? If so, are strategies used to defend the epistemic virtues of TE’s equally available to defend the cognitive claims of works of fiction? In addressing the third of these questions, I spell out the range of responses elicited by the epistemological problern of TE’s in science and suggest that at least one of this responses might bear upon the credibility of the cognitive claims of fiction.