Dissertations / Theses on the topic 'Conditionals'

Conditional statements of the form if p then q and q if p invite a reader to think hypothetically about the world as it is, how it could be, or how it could have been. The way we reason with conditional information has traditionally been studied using highly analytical deduction tasks. However, in everyday discourse readers must rapidly and efficiently comprehend conditional statements about real world events, in real time, to maintain coherence with the wider narrative. To date, there has been little attention paid to understanding the cognitive processes that contribute to this type of fast-acting and intuitive comprehension. In the series of experiments reported in this thesis, a temporally fine grained reading time measure was employed to track the real-time processing load associated with the pragmatic and probabilistic factors that constrain the interpretation of everyday conditional statements. These experiments revealed that (1) the scope of hypothetical thinking is differentially constrained for indicative and counterfactual conditionals (2) these constraints differ as a function of clause order (3) readers mentally represent the speech act communicated by a conditional (4) the initial representation of an indicative conditional captures the conjunctive probability of the events described by p and q occurring together i.e., P(pq). Conditionals have traditionally been examined as disinterested arbitrary propositions. Recent advances have extended this analysis to the types of conditional we encounter on a daily basis. The findings presented provide a further advance, showing that the incremental real time interpretation of a conditional statement entails multiple levels of pragmatic and probabilistic representation. If current theories of conditionals are to capture the processes involved in everyday human reasoning, they must be refined by testing their implicit processing assumptions, and ultimately used to generate explicit processing predictions that can guide future empirical work.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, February 2007.
Includes bibliographical references (leaves 105-108).
This thesis consists of three interconnected papers on apriority, modality, and conditionals. In "Playground Conditionals," I look at three philosophical debates, each of which turns on the epistemic status of a certain kind of conditional-what I call a playground conditional. I argue that a close consideration of playground conditionals gives us a better appreciation of what we can do with conditionals and, ultimately, some guidance concerning what to say about the three philosophical debates. In "Modal Rationalism, Two Dimensionalism, and our Counteractual Sisters", I consider the prospects for modal rationalism in the wake of Kripke's Naming and Necessity. Recently there has been a modal rationalist revival, thanks in part to the development of the "two-dimensional" semantic framework. This framework associates two intensions (a primary intension and a secondary intension) with every sentence. The difficulty comes in finding a definition of primary and secondary intension that would lend the desired support to modal rationalism. After exploring and rejecting some of the proposed definitions in the literature, I sketch an account that can, I think, offer some support to a suitably framed modal rationalism.
(cont.) Finally, in "A Guide to Modal Guidance," I set about to get clearer on how, exactly, we come to know modal truths. I start by considering two arguments that are designed to show that our access to modal knowledge cannot come from conceivability arguments. I show that, these arguments are mistaken. In the process, I attempt to outline a broader and more realistic modal epistemology than one that focuses exclusively on conceivability. I then consider and reject a version of modal rationalism which says that ideal conceivability gives us a priori access to modality. Against this, I argue that our modal knowledge is predominantly a posteriori, and that our knowledge of ideal conceivability is always a posteriori. In the end, however, I attempt to salvage something that preserves the spirit, if not the letter, of modal rationalism.
by Jason Decker.
Ph.D.

This dissertation conducts an investigation into nonmonotonic reasoning---forms of reasoning which allow defeasible inferences arrived at in the absence of complete information, and which, when additional information is acquired, may need to be revoked. In contrast to the mathematical notion of consequence which is based on proof---mathematical proofs, once established, are beyond reproach, no matter what additional information is acquired---nonmonotonic forms of reasoning are often employed in Artificial Intelligence, where generally only incomplete information is available, and often 'working' inferences need to be made; e.g. default inferences. The platform on which this analysis of nonmonotonic reasoning is carried out is conditional logic; a relative of modal logic. This thesis explores notions of consequence formulated in conditional logic, and explores its possible-worlds semantics, and its connection to nonmonotonic consequence relations. In particular, the notion of default consequence is explored, receiving the interpretation that something is inferred to be true by default if it holds in a `majority' of possible worlds. A number of accounts of majority-based reasoning appear in the literature. However, it is argued that some of the more well known accounts have counter-intuitive properties. An alternative definition of `majorities' is furnished, and both modal and conditional formulations of this form of inference are given and compared---favourably---with similar approaches in the literature. A second, traditional problem of reasoning in Artificial Intelligence is tackled in this thesis: reasoning about action. The treatment presented is again based on conditional logic, but also incorporates an account of dynamic logic. The semantics proposed approaches the frame problem from a different perspective; the familiar `minimal change' approach is generalised to an account based on the principle known as Occam's Razor. The conditional introduced proves to be a valuable contribution to the account given---which again is compared, and contrasted with other approaches in the literature---accommodating a causal approach to the problem of correctly determining the indirect effects of an action.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
INSTITUTO MILITAR DE ENGENHARIA
CENTRO TECNOLÓGICO DO EXÉRCITO
INSTITUTO DE PESQUISA E DESENVOLVIMENTO
Apresentamos uma lógica para a compreensão de condicionais a partir da proximidade (PUC-Logic) que unifica as lógicas Contrafactual e Deôntica propostas por David Lewis. Propomos também um sistema de dedução natural (PUC-ND) associado a essa nova lógica. Esse sistema de inferência é correto, completo, normalizável e decidível. A completude relativa para as lógicas V e CO é apresentada para dar ênfase à abordagem unificada sobre o trabalho de Lewis. Depois disso, apresentamos uma perspectiva construtivista para mostrar que a abstração contrafactual de Lewis não exige a regra do absurdo clássico.
We present a logic for Proximity-based Understanding of Conditionals (PUC-Logic) that unifies the Counterfactual and Deontic logics proposed by David Lewis. We also propose a natural deduction system (PUC-ND) associated to this new logic. This inference system is proven to be sound, complete, normalizing and decidable. The relative completeness for the V and CO logics is shown to emphasize the unified approach over the work of Lewis. We, then, present a constructive approach to counterfactuals to show that the Lewis counterfactual abstraction does not require the classical absurd rule.

This dissertation is concerned with the relationship between morphological tense forms of Japanese, such as (r)u ("non-past") and ta ("past"), and their temporal interpretation. The goal of the research reported here is to establish a simple overall theory. The analysis focuses on the following sentence types: simple sentences, complex sentences (without conditional sentences), conditional complex sentences and sentences with an embedded clause. We will show here a few examples of problems as to temporal interpretations. In simple sentences, there are cases such as (1), which deviate from the norm of "normal" interpretation. Sentence (1) (with the “past” form of ta) can be uttered felicitously even in a situation where the bus in question has not yet arrived. (1)Busu ga ki-ta! Bus nom come-ta ‘The bus is coming.’ Or ‘The bus has come.’ In complex sentences, the antecedent clause in sentences with toki 'when', can take either (r)u or ta forms in sentence (2), while it cannot take the ta form in sentence 93), although the antecedent clauses in both sentences are interpreted as non-past. (2) Kondo a-u/at-ta toki, hanashi-ma-su. Next-time see-(r)u/see-ta toki talk-polite-(r)u ‘Next time when (I) see (you), (I) will tell (it to you).’ (3)Yuushoku o su-ru/*shi-ta toki, biiru o nom-u. supper acc do-(r)u/do-ta toki beer acc drink-(r)u ‘When (I) take supper, (I) will drink beer.’ In regard to conditional complex sentences, there can be a problem interpreting ta, as in hypothetical sentence (4) below. The ta of the consequent clause in example (4) cannot be evaluated (interpreted) as being the same as the ta in example (5) where we have an indicative sentence. (4) Taroo wa benkyoo shi-ta ra, shaken ni pasu shi-ta (no ni). Taro top study do-ta ra exam in pass do-ta (SFP-‘wishing’) ‘Had Taro studied, he should/would have passed the exam.’ (5) Taroo wa shiken ni pasu shi-ta. ‘Taro passed the exam.’ In this account the morphemes (r)u and ta will be associated with a single interpretation. Therefore, the difference between (2) and (3) will be attributed to two distinct modes of composition. In order to solve the problem of simple sentences wuch as (1) (which deviate from the norm of "normal interpretations"), a pragmatic (contextual) approach will be introduced. In regard to conditional sentences, interpretations will be classified on the basis of truth relations and temporal interpretations of antecedent and consequent. In order to treat the range of observed truth relations, a model of time and worlds will be introduced. In summary, in order to solve the problematic phenomena of relationships between the tense forms and their interpretations, the following approaches will be taken: (i) Use of a time model; (ii) Analysis of lexical properties; (iii) Sentence composition; (iv) Contextual analysis for pragmatic aspects.

This thesis is essentially a portfolio of four disjoint yet thematically related articles that deal with some semantic aspect or another of natural language conditionals. The thesis opens with a brief introductory chapter that offers a short yet opinionated historical overview and a theoretical background of several important semantic issues of conditionals. The second chapter then deals with the issue of truth values and conditions of indicative conditionals. So-called Gibbard Phenomenon cases have been used to argue that indicative conditionals construed in terms of the Ramsey Test cannot have truth values. Since that conclusion is somewhat incredible, several alternative options are explored. Finally, a contextualised revision of the Ramsey Test is offered which successfully avoids the threats of the Gibbard Phenomenon. The third chapter deals with the question of where to draw the so-called indicative/ subjunctive line. Natural language conditionals are commonly believed to be of two semantically distinct types: indicative and subjunctive. Although this distinction is central to many semantic analyses of natural conditionals, there seems to be no consensus on the details of its nature. While trying to uncover the grounds for the distinction, we will argue our way through several plausible proposals found in the literature. Upon discovering that none of these proposals seem entirely suited, we will reconsider our position and make several helpful observations into the nature of conditional sentences. And finally, in light of our observations, we shall propose and argue for plausible grounds for the indicative/subjunctive distinction.distinction. The fourth chapter offers semantics for modal and amodal natural language conditionals based on the distinction proposed in the previous chapter. First, the nature of modal and amodal suppositions will be explored. Armed with an analysis of modal and amodal suppositions, the corresponding conditionals will be examined further. Consequently, the syntax of conditionals in English will be uncovered for the purpose of providing input for our semantics. And finally, compositional semantics in generative grammar will be offered for modal and amodal conditionals. The fifth and final chapter defends Modus Ponens from alleged counterexamples. In particular, the chapter offers a solution to McGee’s infamous counterexamples. First, several solutions offered to the counterexamples hitherto are all argued to be inadequate. After a couple of observations on the counterexamples’ nature, a solution is offered and demonstrated. the solution suggests that the semantics of embedded natural language conditionals is more sophisticated than their surface syntax indicates. The heart of the solution is a translation function from the surface form of natural language conditionals to their logical form. Finally, the thesis ends with a conclusion that briefly summarises the main conclusions drawn in its preceding chapters.

This thesis studies the reasoning behaviour of successful mathematicians. It is based on the philosophy that, if the goal of an advanced education in mathematics is to develop talented mathematicians, it is important to have a thorough understanding of their reasoning behaviour. In particular, one needs to know the processes which mathematicians use to accomplish mathematical tasks. However, Rav (1999) has noted that there is currently no adequate theory of the role that logic plays in informal mathematical reasoning. The goal of this thesis is to begin to answer this specific criticism of the literature by developing a model of how conditional “if…then” statements are evaluated by successful mathematics students. Two stages of empirical work are reported. In the first the various theories of reasoning are empirically evaluated to see how they account for mathematicians’ responses to the Wason Selection Task, an apparently straightforward logic problem (Wason, 1968). Mathematics undergraduates are shown to have a different range of responses to the task than the general well-educated population. This finding is followed up by an eve-tracker inspection time experiment which measured which parts of the task participants attended to. It is argued that Evans’s (1984, 1989, 1996, 2006) heuristic-analytic theory provides the best account of these data. In the second stage of empirical work an in-depth qualitative interview study is reported. Mathematics research students were asked to evaluate and prove (or disprove) a series of conjectures in a realistic mathematical context. It is argued that preconscious heuristics play an important role in determining where participants allocate their attention whilst working with mathematical conditionals. Participants’ arguments are modelled using Toulmin’s (1958) argumentation scheme, and it is suggested that to accurately account for their reasoning it is necessary to use Toulmin’s full scheme, contrary to the practice of earlier researchers. The importance of recognising that arguments may sometimes only reduce uncertainty in the conditional statement’s truth/falsity, rather than remove uncertainty, is emphasised. In the final section of the thesis, these two stages are brought together. A model is developed which attempts to account for how mathematicians evaluate conditional statements. The model proposes that when encountering a mathematical conditional “if P then Q”, the mathematician hypothetically adds P to their stock of knowledge and looks for a warrant with which to conclude Q. The level of belief that the reasoner has in the conditional statement is given by a modal qualifier which they are prepared to pair with their warrant. It is argued that this level of belief is fixed by conducting a modified version of the so-called Ramsey Test (Evans & Over, 2004). Finally the differences between the proposed model and both formal logic and everyday reasoning are discussed.

Hur har vi kunskap om vad som är möjligt? Enligt vad som kan betraktas som det traditionella svaret till den frågan, har vi kunskap om modalitet via föreställningsbarhet. Vi föreställer oss ting och tar sedan detta som bevis för möjlighet. Denna uppsats kommer att undersöka tre invändningar till detta svar angående hur vi har kunskap om möjlighet. Vi kommer sedan att överväga Williamsons förmodan: att vår kognitiva kapacitet för att hantera kontrafaktiska konditionaler bär med sig den kognitiva kapaciteten för oss att även hantera metafysisk modalitet (2007, 136), och undersöka om denna förmodan undviker dessa invändningar. Det kommer här att argumenteras att Williamson’s förmodan undviker två av invändningarna och att den inte tycks kunna svara på den sista invändningen. Det kommer även att argumenteras att en invändning mot Williamson’s förmodan ser ut att vara särskilt problematisk, och att det inte är klart att Williamson’s förmodan är i någon bättre position än den negativa föreställningsbarhets vyn.
How do we have knowledge of what is possible? On what could be considered as the traditional response to this question, we have knowledge of modality by conceivability. We conceive of things and on the basis take this as evidence for possibility. This thesis will consider three objections to this response of how we have knowledge of possibility. We will then consider Williamson’s conjecture: that our cognitive capacity to handle counterfactual conditionals carries the cognitive capacity for us to also handle metaphysical modality (2007, 136), and see if this conjecture avoids these objections. It will be argued that Williamson’s conjecture avoids two of the objections and that it does not seem to have a response to the last objection. It will also be argued that one objection to Williamson’s conjecture seems particularly problematic, and that it is not so clear that Williamson’s conjecture is any better off than the negative conceivability view.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 2002.
Includes bibliographical references (p. 191-194).
This dissertation is a study of modality and, in particular, of conditional statements within the framework of possible world semantics. I argue that in order to understand what the meaning of a modal sentence is we need to look closely at the internal composition of accessibility relations. Accessibility relations are shown to be complex relations involving both a world and a time of evaluation, and it is shown that temporal and aspectual operators can be interpreted in the modal domain, and may not occur inside the scope of the modal operator. When interpreted in this position, temporal and aspectual operators contribute to the selection of the possible worlds by defining the relevant notion of accessibility. Capitalizing on work by Irene Heim, David Lewis and Robert Stalnaker, I show that this proposal allows us to develop a semantic analysis of those conditionals that are traditionally called subjunctive conditionals, and to provide an answer to how to select the worlds that the modal operator quantifies' over. Finally, I argue that the semantic analyses of counterfactuals discussed by Lewis (1979) - Analysis 1 and Analysis 2 - cannot be maintained in that neither of them accounts for the contrast between the felicity conditions of different types of subjunctive conditionals. Instead, I will argue that our theory based on a time-dependent notion of accessibility can.
by Michela M. Ippolito.
Ph.D.

This study presents an analysis of conditional constructions in Yorùbá, as well as its implications for language-specific phenomena which are part of the Yorùbá phrase structure. Specifically, I propose a model for the interpretation of conditionals that is based on a tripartite quantificational structure. It is an explanatory model capturing the interdependency between meaning and form. It accounts not only for the Yorùbá data, but also for those in other languages (English, French, Italian and Polish), allowing at the same time for making crosslinguistic predictions. Crucially, the model reflects both: (i) CONDITION (restrictor)-RESULT (nuclear scope) partition of conditional constructions and (ii) existence of two situation factors: (UN)LIKELIHOOD OF SATISFACTION and TIME OF CONDITION, which play pivotal role in meaningform mapping. Note that, even though both factors contribute to overall interpretation, forms attested are a direct reflection of ways in which languages manipulate these factors in the process of mapping meaning onto form. E.g.: active UNLIKELIHOOD OF SATISFACTION yields two types of conditionals (REALIS and IRREALIS) in Yorùbá, while the three forms attested in the Standard Average European languages (INDICATIVE, NON-PAST SUBJUNCTIVE and PAST SUBJUNCTIVE) result from LIKELIHOOD OF SATISFACTION and TIME OF CONDITION being equally active. The above translates further onto differences in morpho-syntactic marking of conditional forms due to the fact that (UN)LIKELIHOOD OF SATISFACTION and TIME OF CONDITION factors are realised on the surface as Mood and Tense respectively. Moreover, this analysis of conditionals provides important insights into the PHRASE STRUCTURE of Yorùbá. It explains: (i) structural complexity of the future marker yóò which spans across the Mood, Time (Tense/Aspect) and Modal categories; (ii) meaning differences expected between the three future markers: yóò, ˋ á and máa (known for its aspectual readings) and based on their internal elements; (iii) the status of the High Tone Syllable - the Time (Tense/Aspect) marker; (iv) dialectal differences - future being marked by irrealis marker in Moba; and so on. I also argue that there exist two system-specific binary oppositions: (i) MARKEDNESS OPPOSITION(S) that specifies tonal value within each syntactic category and (ii) TONE POLARITY that determines tonal melody between adjacent syntactic categories.
Arts, Faculty of
Linguistics, Department of
Graduate

Numerous recent publications on the psychological meaning of “if” have proposed a probabilistic interpretation of conditional sentences. According to the proponents of probabilistic approaches, sentences like “If the weather is nice, I will be at the beach tomorrow” (or “If p, then q” in the abstract version) express a high probability of the consequent (being at the beach), given the antecedent (nice weather). When people evaluate conditional sentences, they assumingly do so by deriving the conditional probability P(q|p) using a procedure called the Ramsey test. This is a contradicting view to the hitherto dominant Mental Model Theory (MMT, Johnson-Laird, 1983), that proposes conditional sentences refer to possibilities in the world that are represented in form of mental models. Whereas probabilistic approaches gained a lot of momentum in explaining the interpretation of conditionals, there is still no conclusive probabilistic account of conditional reasoning. This thesis investigates the potential of a comprehensive probabilistic account on conditionals that covers the interpretation of conditionals as well as conclusion drawn from these conditionals when used as a premise in an inference task. The first empirical chapter of this thesis, Chapter 2, implements a further investigation of the interpretation of conditionals. A plain version of the Ramsey test as proposed by Evans and Over (2004) was tested against a similarity sensitive version of the Ramsey test (Oberauer, 2006) in two experiments using variants of the probabilistic truth table task (Experiments 2.1 and 2.2). When it comes to decide whether an instance is relevant for the evaluation of a conditional, similarity seems to play a minor role. Once the decision about relevance is made, believability judgments of the conditional seem to be unaffected by the similarity manipulation and judgments are based on frequency of instances, in the way predicted by the plain Ramsey test. In Chapter 3 contradicting predictions of the probabilistic approaches on conditional reasoning of Verschueren et al (2005), Evans and Over (2004) and Oaksford & Chater (2001) are tested against each other. Results from the probabilistic truth table task modified for inference tasks supports the account of Oaksford and Chater (Experiment 3.1). A learning version of the task and a design with every day conditionals yielded results unpredicted by any of the theories (Experiments 3.2-3.4). Based on these results, a new probabilistic 2-stage model of conditional reasoning is proposed. To preclude claims that the use of the probabilistic truth table task (or variants thereof) favors judgments reflecting conditional probabilities, Chapter 4 combines methodologies used by proponents of the MMT with the probabilistic truth table task. In three Experiments (4.1 -4.3) it could be shown for believability judgments of the conditional and inferences drawn from it, that causal information about counterexamples only prevails, when no frequencies of exceptional cases are present. Experiment 4.4 extends these findings to every day conditionals. A probabilistic estimation process based on frequency information is used to explain results on all tasks. The findings confirm with a probabilistic approach on conditionals and moreover constitute an explanatory challenge for the MMT. In conclusion of all the evidence gathered in this dissertation it seems justified to draw the picture of a comprehensive probabilistic view on conditionals quite optimistically. Probability estimates not only explain the believability people assign to a conditional sentence, they also explain to what extend people are willing to draw conclusions from those sentences.
Zahlreiche aktuelle Publikationen über die psychologische Bedeutung der Worte „Wenn - dann“ schlagen eine probabilistische Interpretation von Konditionalen vor. Vertretern dieses probabilistischen Ansatz zufolge drücken Sätze der Form „Wenn das Wetter schön ist, dann bin ich morgen am Strand“ (oder „Wenn p, dann q“ in der abstrakten Version) eine hohe Wahrscheinlichkeit des Konsequenten (am Strand sein), gegeben den Antezedenten (schönes Wetter) aus. Menschen beurteilen demnach Konditionalsätze, indem sie die bedingte Wahrscheinlichkeit P(q|p) mit Hilfe eines Ramsey-Tests abschätzen (Evans & Over, 2004). Diese Sichtweise stellt einen Gegenentwurf zur bisher dominanten Theorie mentaler Modelle (Johnson-Laird, 1983) dar, die davon ausgeht, dass Konditionalsätze Aussagen über Möglichkeiten machen, die in Form mentaler Modelle repräsentiert werden. Obwohl probabilistische Ansätze in den letzten Jahren überzeugende Evidenz für eine probabilistische Interpretation von Konditionalen präsentiert haben, gibt es noch keine überzeugende probabilistische Erklärung für konditionales Schließen. Die vorliegende Doktorarbeit leistet einen Beitrag zu einer umfassenden probabilistischen Theorie von Konditionalen, die die Interpretation und die Ziehung von Schlüssen aus Konditionalsätzen umfasst.

This thesis examines the difference between conditional phrases in Egyptian Colloquial (EC) and Modern Standard Arabic (MSA). It focuses on two different conditional particles 'iḏa and law. Verb tenses featured after the conditional particle determine the difference between EC and MSA usage. Grammars for EC and MSA provide a prescriptive approach for a comparison with empirical data from Arabic corpora. The study uses data from the ArabiCorpus along with a corpus of Egyptian Colloquial that were compiled specifically for this study. The results of this study demonstrate that each particle (‘iḏa and law) and register (EC and MSA) favors a certain tense. Also, the data contrast with rules prescribed by grammars for MSA. Present tense verbs appear in the proposed condition for particle law a total of 22 out of 400 tokens (5.5%). Verb tense also plays an important role in determining the connecting particle for MSA sentences. The results demonstrate that the selection of connecting particles for law does not occur by chance but is instead systematic in nature. An apodosis containing a past tense verb strongly favors the connecter la, while one with a non-past tense verb strongly favors the connector fa.

The motivation for this study is two-pronged. A number of studies on modality or conditionals have put forward the claim that conditionality, and conditionals, have a special relationship with modality. However, this claim has not been empirically investigated, or established quantitatively, nor has the nature of this relationship been examined. Furthermore, although existing classifications of conditionals take account of modal marking, they do not do so consistently, nor do they take account of all modality types. This study, therefore, examines the relation of conditionals to modality using the written BNC, and develops two complementary metrics for the extent of modal marking (modal load): modal density and modalisation spread. It establishes the modal load in a random sample of if-conditionals, and compares it to that of written English, as well as other conditionals, and a number of non-conditional bi-partite constructions. The examination also compares the modal load in different types of if-conditionals, and their two parts (protasis and apodosis), and motivates the development of a typology of ifconditionals. Finally, the study examines the modal nature of if-conditionals in light of two current theories, Lexical Grammar and Construction Grammar. The analysis confirms, and provides a quantitative measure of, the connection between conditionals and modality. It also supports a two-dimensional classification of if-conditionals which takes into account the interaction of the modal function of the conditional and the nature of link holding between its two parts, while providing frequency information on the types established. The analysis also indicates that there is a correlation between types of conditionals and modal load patterns in their respective protases and apodoses. In light of the above, the study proposes a conception of conditional constructions as environments of indeterminacy, drawing on mental space theory and quantum mechanics, and proposes an expansion of the notion of construction family.

SUMARYThe main aim of this doctorate research is to design an instructional model- a macro-grammar strategy- which combines grammar and strategy researchers' contributions to help foreign language learners learn an L2 more autonomously. However, this research is specially motivated by our concern about the poor results which Spanish secondary school students achieve in Spanish schools in their written exams, since passing a written exam to get into university is these students' main objective. The reasons for this failure may be due to an excessively communicative approach and too wide a variety of students sharing the same classroom. Therefore, though the purpose of this research is to help all students to learn grammar more autonomously thanks to their acquisition of metacognitive (selective attention, self-monitoring and self-evaluation) and cognitive strategies (elaboration, induction, translation, deduction, repetition and transfer), this study is specially concerned about unsuccessful learners who lack or do not apply the metacognitive and cognitive strategies necessary to learn grammar and transfer their acquired knowledge to the acquisition of new grammatical structures, since this model may enable students to learn on their own and improve their attitude towards foreign language learning. Our research is based on cognitive theory of learning. The theoretical background which supports our research attempts to demonnstrate how cognitive theory of learning manages to explain how learning, an L2, grammar and strategies, are learnt; and how the automatization of grammar and strategies helps students learn an L2. According to this approach the learner becomes an active organizer of incoming information and an L2 acquisition is seen as the acquisition of a complex, cognitive skill in which the learning of grammar plays an important role and LS facilitate its learning (McLaughlin, Rossman, and McLeod, 1983). This cognitive approach also states that grammar and learning strategies (LS) are complex skills; and explains how a skill is learnt so that the learning of an L2, grammar and LS can be understood. Thus, Anderson's (1980) theory of knowledge acquisition, McLaughlin's (1987), Schmidt's (1990), Sharwood-Smith's (1993), Long's (1998), Dekeyser's (1998), and Skehan's (1999) position on grammar learning and Wenden's (1987) and O'Malley et al.'s approach to LS manage to complement each other and offer an appropriate theoretical framework for designing an instructional model in which strategy training enables students to learn a grammatical structure and transfer this knowledge to the learning of other structures. The automatization of grammatical items is believed to take place when formally learned grammatical items have been explicitly noticed, have been structured into working hypotheses and have been proceduralized/automatized through practice in context (e.g. McLaughlin, 1987; Schmidt, 1990; Johnson, 1994; Batstone, 1994). And by using metacognitive strategies- planning, monitoring and evaluating strategies- students can come to understand that they have power over their own learning (Chamot and O'Malley, 1996: 266); and the combination of these metacognitive strategies with cognitive strategies- mental steps which involve interacting with the material- will also facilitate learners to learn grammar on their own. The two main hypothesis of this research are that students, specially fair and poor learners, following the grammar strategy instruction will acquire the 2nd conditional structure better than the students who do not follow this instruction: that is to say, their results in the 1st post-test, 2nd post-test, and final post-test will be better. And that the experimental group students, specially poor and fair learners, will transfer their way of acquiring 2nd conditionals to another grammatical structure, in this case the 3rd conditionals, better than the students who do not follow this instruction. Next, the method to be followed in our empirical work is explained. This research in which 60 subjects- 30 experimental subjects and 30 control subjects- participated has been conducted in "Luis Vives" secondary school in Valencia during the school year 2000-2001. Their textbook, their teacher and the conditions under which they study English are the same and their standard is low-intermadiate. Due to the great range of results which students get in the pre-test and their last year's results participants are ranked into three subgroups- good, fair and poor (Izumi and Bigelow, 2000: 248). Students also fill in three metacognitive questionnaires, which analyse students' characteristics, objectives, difficulties, and strategies used to learn grammar, before instruction takes place so that the homogeneity of both groups can be established. Our instructional model combines the explicit training of metacognitive and cognitive strategies when practising comprehension, consciousness-raising, controlled and spontaneous written grammar activities- filling in the blanks with the right tenses, correcting mistakes, rewriting, translating from Spanish into English and writing- on the learning of 2nd conditional sentences in the foreign language classroom. Since it is acknowledged that neither a forms-based instruction nor meaning-based instruction alone can lead to SLA (Doughty and Williams, 1998: 11), our approach is eclectic and combined. Our strategy training is provided in four sessions in three weeks running in January. The declarative knowledge about the 2nd conditional, their induction, practice in controlled and spontaneous written activities, and immediate feedback is provided in each session, while metacognitive and cognitive strategies are practised. Students' answers in the metacognitive questionnaires and their results in the pre-test and four post-tests are analysed following statistical procedures so that we can be more certain of the reliability of the results. A previous pilot study (Viñes, 2000) was also carried out so that possible deficiencies could be avoided, and results could be compared. The results obtained in the two short-term and long-term post-tests confirm our first hypotheses; our instructional model helped learners, specially unsuccessful learners, to learn the 2nd conditional. And the results of the "Discovering the 3rd conditional" test confirms our 2nd hypothesis; our instructional model helped experimental, specially unsuccessful learners, to transfer the knowledge acquired in learning the 2nd conditional to the learning of the 3rd conditionals. However, the results which students get are not 100% correct in all the different activities, that it is why, it is considered that they are still in the associative stage of learning in relation to their learning of 2nd and 3rd conditional sentences, and metacognitive and cognitive strategies. More spontaneous written activities and more strategy training sessions should have been provided in order to help them get to the autonomous stage of learning. Thus, the results of the four post-tests offer relevant empirical evidence on the effectiveness of our instructional model to help learners, specially unsuccessful learners to improve their inductive ability, acquire declarative knowledge, and transfer the declarative knowledge acquired in learning the 2nd conditional to the learning of the 3rd conditional. Finally, some pedagogical implications, which can be specially useful to help secondary school students learn an L2, are suggested. First of all, encouraging students to work on their own in silence may aid poor learners in performing activities. Secondly, providing strategy training which combines metacognitive and cognitive strategies is essential. Thirdly, adapting the material to student's level, and allowing the L1 to be used in the classroom when needed may encourage students to learn. Fourthly, providing smaller amounts of new information in meaningful contexts, but allowing students to discover it, make it explicit, practise it immediately and get feedback, may allow students to perceive learning grammar as a rewarding game because they can be aware of their success. Moreover, repeating this material applied in different contexts within long intervals of time may help all learners to acquire the new structures since different opportunities for their learning are provided. This doctorate research presents the findings of an empirical study carried out in a Spanish secondary school to test the effectiveness of an instructional model designed to help these secondary school students, specially the unsuccessful ones, learn grammar more autonomously and improve their attitude towards foreign language learning. First, the theoretical background which supports our empirical work is described. Anderson (1980, 1981, 1982, 1983), Anderson and Fincham (1994) and Anderson et al.'s (1997) theory of knowledge acquisition, McLaughlin (1987), Schmidt (1990), Sharwood-Smith (1993), Long (1998), Dekeyser (1998), and Skehan's (1999) position on grammar learning and Wenden (1987) and O'Malley and Chamot's (1990) approach to learning strategies complement each other, and offer an adequate framework for designing an instructional model which combines the explicit training of metacognitive and cognitive strategies when practising controlled and spontaneous written grammar activities on the learning of 2nd conditional sentences in the foreign language classroom. Second, the description of our empirical work follows. The experimental and control subjects' characteristics, the description of our instructional model, its instruction, the short-term and long term post-tests taken, and the statistical tests applied on the students' answers make up this description. Third, relevant empirical evidence on the effectiveness of our instructional model to help learners, specially unsuccessful learners to improve their inductive ability, acquire declarative knowledge, and transfer the declarative knowledge acquired in learning the 2nd conditional to the learning of the 3rd conditional are presented and discussed. Finally, some pedagogical implications, which can be specially useful for secondary school teachers when helping secondary school students learn an L2, are suggested.

Logical statements are prevalent in mathematics, the sciences, law, and many areas of everyday life. The most common logical statements are conditionals, which have the form “If H..., then C...,” where “H” is a hypothesis (or condition) to be satisfied and “C” is a conclusion to follow. Reasoning about conditionals is a skill that is only superficially understood by most individuals and depends on four main conditional contexts (e.g., intuitive, abstract, symbolic, or counterintuitive). The purpose of this study was to test a theory about the effects of context ordering on reasoning about conditionals. To test the theory, the researcher developed, tested, and revised a virtual manipulative educational mathematics application, called the Learning Logic App. This study employed a convergent parallel mixed methods design to answer an overarching research question and two subquestions. The overarching research question was “How does the order of teaching four conditional contexts influence reasoning about conditionals?” The two subquestions examined this influence on reasoning in terms of performance and perceptions. This study involved two phases. During Phase I, 10 participants interacted with the Learning Logic App in a clinical setting. The researcher used information gathered in Phase I to revise the Learning Logic App for Phase II. During Phase II, 154 participants interacted with the Learning Logic App in a randomly assigned context ordering in an online setting. In both phases, the researcher collected quantitative and qualitative data. After independent analyses, the researcher made meta- inferences from the two data strands. The results of this study suggest that context ordering does influence learners’ reasoning. The most beneficial context ordering for learners’ performance was symbolic-intuitive-abstract-counterintuitive. The most beneficial context ordering for learners’ perceptions was intuitive-abstract-counterintuitive-symbolic. Based on these results, the researcher proposed a new context ordering: symbolic-intuitive-abstract-counterintuitive-symbolic. This progression incorporates a catalyst at the beginning (symbolic context) which aids the learner in reassessing their prior knowledge. Then, the difficulty of the contexts progresses from easiest to hardest (intuitive-abstract-counterintuitive-symbolic). These findings are important because they provide an instructional sequence for teaching and learning to reason about conditionals that is beneficial to both learners’ performance and their perceptions.

The Functions and the Ordering of Conditional `If Clauses' in English---A Genre AnalysisPrevious research studies are in agreement that the canonical order for English if conditionals is sentence-initial rather than final. However, earlier findings regarding the distribution of the ordering between initial and final if-conditionals represent only those patterns specific to the limited number of genres examined. This corpus linguistic study is based on a research approach which includes a larger sampling pool and a selection of representative genres as well as detailed statistical and content analyses. It examines the variations in the distributional patterns between initial and final if-clauses within each individual genre and across different genres. The findings of this study suggest that if-conditionals have significantly different distributional pattern across genres. In contrast to the consensus view in current literature that initial if-clause rather than final is the dominant clause order, in 3 of the genres examined in this study (Letters to the Editor, Recipes and Sports News) final if-clauses occur more frequently than initial. In addition, in 3 other genres (News Reportage, Science Fiction and Romance Fiction) these two clause types are equally distributed. This study thus identifies genre as a significant factor influencing sentential if-conditional placement.The study also argues that in addition to the expression of topic and focus discourse relations, the ordering of the conditional and consequence clauses is often used to convey specific pragmatic effects and to perform functions related to genre-specific needs, including social politeness and showing power deixis, hedging or strengthening a proposition.
Department of English

The Backward Induction strategy for the Centipede Game leads us to a counterfactual reasoning paradox, The Centipede Game paradox. The counterfactual reasoning proving the backward induction strategy for the game appears to rely on the players in the game not choosing that very same backward induction strategy. The paradox is a general paradox that applies to backward induction reasoning in sequential, perfect information games. Therefore, the paradox is not only problematic for the Centipede Game, but it also affects counterfactual reasoning solutions in games similar to the Centipede Game. The Centipede Game is a prime illustration of this paradox in counterfactual reasoning. As a result, this paper will use a material versus subjunctive/counterfactual conditional analysis to provide a theoretical resolution to the Centipede Game, with the hope that a similar solution can be applied to other areas where this paradox may appear. The solution involves delineating between the epistemic systems of the players and the game theorists.

This thesis presents a series of experiments where endorsement rates, latencies and measures of cognitive ability were collected, to investigate the extent to which people search for counterexamples under necessity instructions, and alternative models under possibility instructions. The research was motivated by a syllogistic reasoning study carried out by Evans, Handley, Harper, and Johnson-Laird (1999), and predictions were derived from mental model theory (Johnson-Laird, 1983; Johnson-Laird & Byrne, 1991). With regard to the endorsement rate data: Experiment 1 failed to find evidence that a search for counterexamples or alternative models took place. In contrast experiment 2 (transitive inference) found some evidence to support the search for alternative models under possibility instructions, and following an improved training session, experiment 3 produced strong evidence to suggest that people searched for other models; which was mediated by cognitive ability. There was also strong evidence from experiments 4, 5 and 6 (abstract and everyday conditionals) to support the search for counterexamples and alternative models. Furthermore it was also found that people were more likely to find alternative causes when there were many that could be retrieved from their everyday knowledge, and that people carried out a search for counterexamples with many alternative causes under necessity instructions, and across few and many causal groups under possibility instructions. .The evidence from the latency data was limited and inconsistent, although people with higher cognitive ability were generally quicker in completing the tasks.

This paper treats the relationship between form and meaning in conditional constructions in Damascus Arabic (DA). More specifically, it treats two, main formal categories of DA conditional constructions: the conditional marker and the verb morphology and, further, how these are related to various degrees of conditional hypotheticality. Apart from the introductory section (Introduction, Aim, Method and Classification of DA), the paper consists of three larger sections: Section 2 gives a basic, theoretical background of crosslinguistic conditional constructions as well as what previous scholars have said about the crosslinguistic relationship between conditional form and meaning. It is found that many of these scholars tend to describe form, but neglect deeper discussions of meaning. This section also provides a general background of the verbal system in DA and the primary TAM (Tense-Aspect-Mood) categories of DA verb forms. The main analysis of this thesis is found in section 3. In this section, I first suggest a method of analysis called ‘the hypotheticality continuum’ which is then employed in the following sub-sections, following Comrie (1986). Thereafter, attention is first paid to DA protasis markers and how the choice of marker is related to hypotheticality. Thirdly, I deal with verb morphology and how the choice of verb form together with a given protasis marker contributes to creating even more fine-grained distinctions of hypotheticality in DA conditional constructions. Lastly, a presentation of results and final discussion in section 4 conclude the paper.

Orientador: Maria Luiza Braga
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Estudos da Linguagem
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Resumo: Neste trabalho, investigo as orações hipotáticas de tempo e condição presentes na fala de crianças em fase de aquisição de primeira língua. Na literatura consultada, há um consenso de que as orações temporais emergem na fala da criança primeiro do que as condicionais. Como sugere Slobin (1975), algumas noções, por serem mais salientes psicologicamente do que outras, são primeiramente desenvolvidas na infância. Os dados, no entanto, permitem afirmar apenas que as primeiras ocorrem em maior número do que as segundas. A justificativa, nesse caso, remete tanto a Givón quanto a Heine et alii. Tomando por base os pressupostos de Givón (1995), pode se dizer que as temporais representam estruturas não-marcadas, uma vez que são menos freqüentes. Nesse caso, é provável que tendam a ser, ao contrário das condicionais, menos complexas. Uma outra hipótese remete ao continuum de categorias cognitivas proposto por Heine et alii (1991), que defende que entidades mais concretas, como as que se referem a TEMPO, podem ser recrutadas para expressar noções mais abstratas, como CONDIÇÃO. Mostro, entre outros aspectos que, em algumas orações, é possível identificar uma superposição de significados temporais e condicionais, e que, em outras, essa possibilidade é, senão bloqueada, pelo menos, mais difícil. A correlação modo-temporal e o grau de hipoteticidade explicam, parcialmente, a intercambialidade entre noções temporais e condicionais. Para aferir o grau de integração dessas orações, utilizei as variáveis correlação modo-temporal, explicitude, correferencialidade e formas de expressão dos sujeitos. Em relação ao primeiro parâmetro, os resultados empíricos sugerem que as construções de tempo, por apresentarem tempos e modos idênticos tanto na núcleo quanto na temporal, estão mais integradas, e, portanto, mais gramaticalizadas. No que concerne aos outros parâmetros, parece haver uma inversão nos resultados. Casos de anáfora zero, que indicam um grau forte de entrelaçamento, foram registrados mais nas orações condicionais do que nas temporais. Todavia, em ambas estruturas, os sujeitos apresentaram os traços [- correferencialidade] e [+ explicitude], que indicam relações sintáticas mais frouxas
Abstract: This study investigates the hypotactic temporal and conditional clausespresent in the speech pattems of children who are in the language acquisition phase. According to the literature researched there is consensus that temporal clauses emerge in children speech patterns before conditional clauses. Like Slobin (1975) suggests, some notions, being more visible than others frem a psychological perspective, are the first to be developed in childhood. In my data, however, I verified to a certain extent that the first occur in greater number than the latter. In this case, the justification points to the hypotheses of both Givón and Heine et aloTaking Givón's pressupositions as a basis, I can say that the temporal clauses are unmarked structures, once they are less frequent. In this case, it is possible that they tend to be, contrary to condicional clauses,less complex. Another hypotheses alludes to the continuum of cognitive categories proposed by Heine et al (1991), which defends that concrete entities are recruited to express more abstract notions, such as condition. I emphasize, among other aspects, that in some sentences it is possible to identify a superposition of temporal and conditional meanings and that, in other sentences, this possibility is, if not blocked, at least less apparent. The modus-temporal correlation and hypothetical explanation ratio partially explain the interchangeability of temporal and conditional notions. In order to assess the integration degree of these sentences I used the sharing of tenses and moods, co-reference and expressions forros of subject variables. As regards the first parameter, empiric outcomes suggest that temporal constructions, because identical tenses and modes are presented in both the nucleus and the temporal clause, are more integrated and therefore characterized by more marked grammaticalization. Conceming the other parameters there seems to be an inversion of results. Cases of total absence of anaphora, which indicate a strong degree of interchange, were found more frequently in conditional than in temporal clauses. However, in both structures the subjects presented signs that indicate looser syntactic relationships [- co-reference] e [+ explicitness]
Mestrado
Mestre em Linguística

In this dissertation, I deal with the problem of presupposition projection. I mostly focus on compound sentences composed of two clauses and conditional sentences in which the second clause carries a presupposition. The central claim is that the presupposition carried by the second clause projects by default, with the exception of cases in which the presupposition entails the first clause (or, in disjunctive sentences, the negation of the first clause). In the latter cases, the presupposition should not project, since it is logically stronger than the first clause (or its negation). Thus, in conjunctions, if the presupposition projected, the speaker’s assertion of the first clause would be uninformative. As for conditionals and disjunctions, if the presupposition projected, the speaker would show inconsistency in his/her beliefs by showing uncertainty about the truth value of the first clause (or its negation). I argue that, in conditionals, this uncertainty is conversationally implicated whereas, in disjunctions, it results from the context’s compatibility with the first disjunct. I maintain that, in cases where projection is blocked, the presupposition is conditionalized to the first clause (or its negation). I demonstrate that the conditionalization is motivated in a straightforward way by the pragmatic constraints on projection just described and that, contrary to what is defended by the so-called ‘satisfaction theory’, presupposition conditionalization is a phenomenon independent from local satisfaction.
En esta tesis, trato el problema de la proyección de presuposiciones. Me centro mayoritariamente en oraciones compuestas de dos cláusulas y en oraciones condicionales cuya segunda cláusula contiene una presuposición. El argumento central es que la presuposición contenida en la segunda cláusula proyecta por defecto, con la excepción de casos en los que la presuposición entraña la primera cláusula (o, en las oraciones disyuntivas, la negación de la primera cláusula). En estos últimos casos, la presuposición no debería proyectar, puesto que es lógicamente más fuerte que la primera cláusula (o su negación). Por tanto, en las oraciones conjuntivas, si la presuposición proyectase, la aseveración de la primera cláusula por parte del hablante no sería informativa. En cuanto a las oraciones condicionales y disyuntivas, si la presuposición projectase, el hablante mostraría inconsistencia en sus creencias al mostrar incertidumbre acerca del valor de verdad de la primera cláusula (o su negación). Sostengo que, en oraciones condicionales, esta incertidumbre es implicada conversacionalmente mientras que, en las oraciones disyuntivas, resulta de la compatibilidad contextual de la primera cláusula. Mantengo que, en casos en los que la proyección es bloqueada, la presuposición es condicionalizada a la primera cláusula (o su negación). Demuestro que la condicionalización es motivada de manera directa por las restricciones de tipo pragmático descritas arriba y que, contrariamente a la idea defendida por la así llamada ‘teoría de la satisfacción’, la condicionalización de la presuposición es un fenómeno independiente de la satisfacción local de la misma.

Orientador: Ítala Maria Loffredo D'Ottaviano
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciências Humanas
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Resumo: O objetivo desta Tese consiste em defender que (a) os condicionais constituem a forma lógica subjacente à manifestação das leis naturais, das leis biológicas e dos hábitos psicocomportamentais. Defendemos, também, que, (b) embora tenhamos a mesma forma lógica subjacente à manifestação dessas regularidades (leis, hábitos), não temos, contudo, o mesmo grau de conexão entre antecedentes e conseqüentes nesses contextos de realidade (físico-químico, biológico e psicocomportamental). Em concordância com a nossa interpretação de parte da Hipótese Cosmológica de Peirce, defendemos que: (c) as leis naturais fortemente determinam seus conseqüentes (Se o antecedente acontece, então o conseqüente quase-necessariamente se segue), (d) as leis biológicas moderadamente determinam seus conseqüentes (Se o antecedente acontece, então o conseqüente muito provavelmente se segue) e (e) os hábitos psicocomportamentais fracamente determinam seus conseqüentes (Se o antecedente acontece, então o conseqüente provavelmente se segue). Anexamos o rótulo Hipótese do Espectro de Determinação de Condicionais Causais a essas diferentes (quase-necessária, muito provável e provável) modalidades de conexão entre antecedentes e conseqüentes. Oferecemos (f), com base na semântica de David Lewis (2005), um modelo para esse espectro de determinação, e procuramos expressar a determinação do condicional e, ao mesmo tempo, deixar espaço para a indeterminação ou acaso. Procuramos (g) caracterizar sistema e organização, e (h) argumentamos que um hábito constitui um componente organizacional da estrutura psicocomportamental de um agente. Oferecemos (i) uma classificação dos hábitos em hábitos que estabelecem os traços da identidade do sistema/agente, hábitos racionais e hábitos degenerados. Procuramos ainda (j) caracterizar a auto-organização e (l) analisar como um processo de auto-organização secundária se estabelece na estrutura psicocomportamental de um agente
Abstract: The objective of this thesis consists in arguing that (a) conditionals constitute the logical form underlying the manifestation of natural laws, biological laws, and psycho-behavioral habits. It is also argued that (b) even though we find the same logical form underlying the manifestation of these regularities (laws and habits), we do not find, however, the same degree of connection between antecedents and consequents in the relevant contexts of reality (physico-chemical, biological, and psycho-behavioral). In accord with our interpretation of part of Peirce's cosmological hypothesis, we argue that (c) natural laws strongly determine their consequents (if the antecedent occurs, then the consequent almost necessarily follows), (d) biological laws moderately determine their consequents (if the antecedent occurs, then the consequent very probably follows), and (e) psycho-behavioral habits weakly determine their consequents (if the antecedent occurs, then the consequent probably follows) We use the appellation "hypothesis of the spectrum of determination of causal conditionals" to express these different modalities of connection between antecedents and consequents (almost-necessary, very probable, and probable). Based on the semantics of David Lewis (2005), we propose (f) a model for this spectrum of determination, and we seek to express the determination of the conditional and, at the same time, to allow room for indetermination or chance. We seek (g) to characterize system and organization, and we argue that (h) a habit constitutes an organizational component in the psycho-behavioral structure of an agent. We offer (i) a threefold classification of habits into habits that establish the features of the identity of the system/agent, rational habits, and degenerate habits. We seek (j) to characterize self-organization, and (k) to analyze how a process of secondary self-organization establishes itself in the psycho-behavioral structure of an agent
Doutorado
Filosofia
Doutor em Filosofia

Social assistance programmes (SAPs), understood as non-contributory transfers aimed at ad-dressing poverty, have spread in developing countries since the late 1990s. National govern-ments in Latin America have sought to extend the coverage of SAPs through human devel-opment conditional cash transfer programmes (CCTs). CCTs share several implementation features. First, they employ targeting and selection methods based on means, and proxy means, tests. Research on targeting and selection methods has evolved hand in hand with the adoption of CCTs in Latin America, Africa and South East Asia. Second, CCTs involve the provision of cash transfers directly to households, but with conditions attached to human development objectives. Transfers are given to households in poverty contingent on investment in the human capital formation of their children. A third feature relates to the presence of programme exit conditions. To date, scarce research is available on the design and outcomes associated with exit condi-tions from CCTs. This thesis thus contributes to the literature in the implementation of SAPs by providing a critical examination of exit conditions in SAPs with specific emphasis on CCTs. The thesis provides a systematic theoretical and empirical analysis of the role of exit conditions in the implementation of CCTs. The thesis develops and tests two basic principles underlying the role of exit conditions. First, the exhausted-effectiveness principle suggests that the effectiveness of a CCT varies over time. The research reported in this examines the effectiveness of programme over time with the aim of identifying potential thresholds after which a given SAP's effectiveness de-clines. A two-period child human capital investment model is developed to study analytically the conditions in which programme effectiveness varies over time. This is examined empirically in order to demonstrate the existence of the time-varying effectiveness associated with the implementation of the Colombia's CCT, Familias en Accion. A continuous treatment effect model is estimated following Hirano and Imbens (2004), in which the length of exposure allows for the graphical analysis of dose-response functions. The results indicate that the design of SAPs must take account of time-varying effectiveness. Second, a principle of the non-recurrence of poverty states that beneficiaries should be able to exit an effective programme when two conditions apply: (i) they are not in poverty; and (ii) they face a low probability of becoming poor in the near future. This principle acknowledges the implications of poverty dynamics for the implementation of SAPs with a particular focus on exit conditions. This thesis characterises the poverty dynamics of beneficiary households through the estimation of a Markovian poverty transition model using data from the Familias en Accion programme. The findings from the empirical work suggest that programme participation should not end when households are non-poor, but attention must be paid to probabilities of recurrence, in order to secure non-recurrence in the near future. Taken together, the exhausted-effectiveness principle interacts with the non-recurrence of poverty principle in the sense that the first sets a maximum length of exposure to the intervention, while the second determines minimum levels of exposure.

We prove some sufficient conditions for obtaining convergence rates in regularization of linear ill-posed problems in a Hilbert space setting and show that these conditions are directly related with the conditional stability in several concrete inverse problems for partial differential equations.

Cette thèse porte sur le raisonnement explicatif : quel rôle les explications jouent-elles dans nos inférences, comment guident-elles nos stratégies d'exploration, et comment nous amènent-elles parfois à l'adoption de fausses croyances ? Ces questions théoriques sont motivées par la philosophie du raisonnement, de la connaissance et de la logique. Elles sont traitées avec les méthodes empiriques des sciences cognitives, au moyen d'expériences comportementales qui utilisent des matériaux concrets et réalistes. La thèse commence par analyser la portée descriptive de l'inférence à la meilleure explication, qui a été théorisée en philosophie comme permettant de justifier les croyances dans des contextes non déductifs. Elle examine ensuite l'inférentialisme, une récente sémantique des conditionnels selon laquelle le sens d'un énoncé conditionnel dépend de la relation entre antécédent et conséquent, relation qui peut être notamment de nature déductive, inductive ou abductive. Elle étudie aussi comment d'autres attitudes épistémiques, notamment les décisions de recherche, prennent en compte la qualité explicative des hypothèses examinées. Enfin, elle propose d'expliquer l'attrait des théories du complot par deux sources : la prédisposition de certaines personnes à un mode de pensée complotiste et l'impression de qualité explicative que ces théories sont capables de produire. Sa conclusion, que les considérations explicatives jouent un rôle important dans le raisonnement et la cognition, constitue une avancée pour les domaines de la philosophie et de la psychologie. Elle souligne aussi la fertilité d'une alliance de ces deux disciplines pour la recherche en sciences cognitives
This research investigates how people reason about explanations: what role do they play in people's inferences, how do they guide people's exploration strategies, and how do they sometimes lead them to endorse false beliefs? These theoretical questions are motivated by the philosophy of reasoning, knowledge and logic. They are pursued with the rigorous empirical methods of cognitive science, using behavioral experiments with realistic and concrete materials. The thesis starts with an examination of the empirical adequacy of inference to the best explanation, an explanatory inference rule that philosophers have theorized to provide grounds for warranted belief in non-deductive contexts. Next, it puts inferentialism to the test, a novel semantic of conditionals according to which the interpretation of a conditional depends on the strength of the relationship between antecedent and consequent, which can be deductive, inductive, or abductive in nature. Then, it considers how other epistemic attitudes, and in particular pursuit decisions, take into account the explanatory quality of the hypotheses being investigated. Finally, it develops an account of belief in conspiracy theories that proposes two types of sources for their appeal: people's predisposition to conspiracist ideation and the explanatory virtues that these theories appear to exhibit. The finding that explanatory considerations play an important role in reasoning and cognition contributes both to the philosophical and psychological literatures; it also emphasizes how fruitful an alliance between these two fields can prove for research in cognitive science