The central topic of the thesis is the relationship between logic and the cognitive psychology of reasoning. This topic is treated in large part through a detailed examination of the recent work of P. N. Johnson-Laird, who has elaborated a widely-read and influential theory in the field. The thesis is divided into two parts, of which the first is a more general and philosophical coverage of some of the most central issues to be faced in relating psychology to logic, while the second draws upon this as introductory material for a critique of Johnson-Laird's `Mental Model' theory, particularly as it applies to syllogistic reasoning. An approach similar to Johnson-Laird's is taken to cognitive psychology, which centrally involves the notion of computation. On this view, a cognitive model presupposes an algorithm which can be seen as specifying the behaviour of a system in ideal conditions. Such behaviour is closely related to the notion of `competence' in reasoning, and this in turn is often described in terms of logic. Insofar as a logic is taken to specify the competence of reasoners in some domain, it forms a set of conditions on the 'input-output' behaviour of the system, to be accounted for by the algorithm. Cognitive models, however, must also be subjected to empirical test, and indeed are commonly built in a highly empirical manner. A strain can therefore develop between the empirical and the logical pressures on a theory of reasoning. Cognitive theories thus become entangled in a web of recently much-discussed issues concerning the rationality of human reasoners and the justification of a logic as a normative system. There has been an increased interest in the view that logic is subject to revision and development, in which there is a recognised place for the influence of psychological investigation. It is held, in this thesis, that logic and psychology are revealed by these considerations to be interdetermining in interesting ways, under the general a priori requirement that people are in an important and particular sense rational. Johnson-Laird's theory is a paradigm case of the sort of cognitive theory dealt with here. It is especially significant in view of the strong claims he makes about its relation to logic, and the role the latter plays in its justification and in its interpretation. The theory is claimed to be revealing about fundamental issues in semantics, and the nature of rationality. These claims are examined in detail, and several crucial ones refuted. Johnson- Laird's models are found to be wanting in the level of empirical support provided, and in their ability to found the considerable structure of explanation they are required to bear. They fail, most importantly, to be distinguishable from certain other kinds of models, at a level of theory where the putative differences are critical. The conclusion to be drawn is that the difficulties in this field are not yet properly appreciated. Psychological explantion requires a complexity which is hard to reconcile with the clarity and simplicity required for logical insights.

A Biologia Molecular e a Biotecnologia e seus conceitos subjacentes estão inseridos no currículo escolar da educação básica e têm estado presentes na vida cotidiana dos estudantes, envolvendo a análise e tomada de decisão sobre aspectos éticos relacionados à produção e aplicação do conhecimento científico e tecnológico. As explicações de alguns fenômenos e processos relacionados a estes temas estão quase sempre no nível molecular e atômico, que é descrito e explicado com modelos conceituais e físicos, ou até mesmo imagens. À luz da Teoria dos Modelos Mentais de Johnson-Laird, as pessoas raciocinam através de modelos mentais, podendo utilizar outras formas de representações mentais como proposições e imagens. Nesse contexto propôs-se diagnosticar entre treze alunos dos cursos de Licenciatura em Ciências Exatas (LCE) e Bacharelado em Ciências Físicas e Biomoleculares (CFBio), ambos cursos da Universidade de São Paulo, quais as representações mentais que esses alunos possuíam sobre o tema proteínas, bem como a contribuição de uma sequência didática utilizando modelos táteis para o ensino e aprendizagem da estrutura e função de proteínas. Para tal, realizamos (a) uma entrevista com os alunos dos cursos mencionados (pré-teste), (b) dois cursos com duração de três dias para cada turma (LCE e CFBio) e (c) uma entrevista com os mesmos alunos transcorrida uma semana após a realização de cada curso (pós-teste). Os dados obtidos foram de três tipos: registros escritos (desenhos e/ ou esquemas); um ou mais modelos táteis montados com materiais de baixo custo; áudio e imagens oriundos das filmagens das entrevistas. Os registros escritos e os modelos táteis de cada aluno foram fotografados e os áudios das entrevistas transcritos, gerando um documento individual que possibilitou uma análise de conteúdo, permitindo a divisão da amostra em duas categorias: alunos modelizadores e não modelizadores, cada uma com subcategorias próprias. A detecção das representações mentais que os alunos possuíam antes e após o curso sinalizou que a contribuição da sequência didática aplicada no curso para o ensino/aprendizagem do tema proteínas foi positiva, promovendo o aumento do número de alunos modelizadores e possibilitando aos mesmos o aumento do nível de complexidade e sofisticação em suas representações externas (modelos táteis e desenhos) e a evolução e esclarecimento de conceitos antes não compreendidos. / The Molecular Biology and Biotechnology and its underlying concepts are embedded in the curriculum of basic education and have been present in the daily life of students, involving the analysis and decision making about ethical issues related to the production and application of scientific and technological knowledge. The explanations of some phenomena and processes related to these themes are almost always in atomic and molecular level, which is described and explained with physical and conceptual models, or even images. In light of the mental models theory of Johnson-Laird, people reason through mental models and may use other forms of mental representations as propositions and images. In this context we proposed diagnose mental representations that students in higher education had on the subject proteins, as well as the contribution of a didactic sequence using tactile models for teaching and learning the structure and function of proteins. Thirteen students of two undergraduation courses Teacher education course in Exact Sciences (LCE) and Bachelor in Biomolecular and Physical Sciences (CFBio) - participated of this research. The tools used for data collection were: (a) an interview with the students of the courses mentioned (pre-test), (b) two courses lasting three days for each group (CFBio and LCE) and (c) an interview with the same students made one week after completion of each course (post-test). The data were of three kinds: written records (drawings and/or diagrams), one or more tactile models assembled with low cost materials, audio and pictures from the filming of the interviews. Written records and tactile models of each student were photographed and audio interviews transcribed, generating an individual document that provided a content analysis, allowing the classification of students in two categories: modellers and non-modellers, each one with its own subcategories. The detection of mental representations that students had before and after the course indicated that the contribution of the didactic sequence for the teaching/learning of the subject proteins was positive, increasing the number of students modellers and enables them (a) increase the level of complexity and sophistication in their external representations (drawings and tactile models) and (b) the development and clarification of concepts not previously understood.

A Biologia Molecular e a Biotecnologia e seus conceitos subjacentes estão inseridos no currículo escolar da educação básica e têm estado presentes na vida cotidiana dos estudantes, envolvendo a análise e tomada de decisão sobre aspectos éticos relacionados à produção e aplicação do conhecimento científico e tecnológico. As explicações de alguns fenômenos e processos relacionados a estes temas estão quase sempre no nível molecular e atômico, que é descrito e explicado com modelos conceituais e físicos, ou até mesmo imagens. À luz da Teoria dos Modelos Mentais de Johnson-Laird, as pessoas raciocinam através de modelos mentais, podendo utilizar outras formas de representações mentais como proposições e imagens. Nesse contexto propôs-se diagnosticar entre treze alunos dos cursos de Licenciatura em Ciências Exatas (LCE) e Bacharelado em Ciências Físicas e Biomoleculares (CFBio), ambos cursos da Universidade de São Paulo, quais as representações mentais que esses alunos possuíam sobre o tema proteínas, bem como a contribuição de uma sequência didática utilizando modelos táteis para o ensino e aprendizagem da estrutura e função de proteínas. Para tal, realizamos (a) uma entrevista com os alunos dos cursos mencionados (pré-teste), (b) dois cursos com duração de três dias para cada turma (LCE e CFBio) e (c) uma entrevista com os mesmos alunos transcorrida uma semana após a realização de cada curso (pós-teste). Os dados obtidos foram de três tipos: registros escritos (desenhos e/ ou esquemas); um ou mais modelos táteis montados com materiais de baixo custo; áudio e imagens oriundos das filmagens das entrevistas. Os registros escritos e os modelos táteis de cada aluno foram fotografados e os áudios das entrevistas transcritos, gerando um documento individual que possibilitou uma análise de conteúdo, permitindo a divisão da amostra em duas categorias: alunos modelizadores e não modelizadores, cada uma com subcategorias próprias. A detecção das representações mentais que os alunos possuíam antes e após o curso sinalizou que a contribuição da sequência didática aplicada no curso para o ensino/aprendizagem do tema proteínas foi positiva, promovendo o aumento do número de alunos modelizadores e possibilitando aos mesmos o aumento do nível de complexidade e sofisticação em suas representações externas (modelos táteis e desenhos) e a evolução e esclarecimento de conceitos antes não compreendidos. / The Molecular Biology and Biotechnology and its underlying concepts are embedded in the curriculum of basic education and have been present in the daily life of students, involving the analysis and decision making about ethical issues related to the production and application of scientific and technological knowledge. The explanations of some phenomena and processes related to these themes are almost always in atomic and molecular level, which is described and explained with physical and conceptual models, or even images. In light of the mental models theory of Johnson-Laird, people reason through mental models and may use other forms of mental representations as propositions and images. In this context we proposed diagnose mental representations that students in higher education had on the subject proteins, as well as the contribution of a didactic sequence using tactile models for teaching and learning the structure and function of proteins. Thirteen students of two undergraduation courses Teacher education course in Exact Sciences (LCE) and Bachelor in Biomolecular and Physical Sciences (CFBio) - participated of this research. The tools used for data collection were: (a) an interview with the students of the courses mentioned (pre-test), (b) two courses lasting three days for each group (CFBio and LCE) and (c) an interview with the same students made one week after completion of each course (post-test). The data were of three kinds: written records (drawings and/or diagrams), one or more tactile models assembled with low cost materials, audio and pictures from the filming of the interviews. Written records and tactile models of each student were photographed and audio interviews transcribed, generating an individual document that provided a content analysis, allowing the classification of students in two categories: modellers and non-modellers, each one with its own subcategories. The detection of mental representations that students had before and after the course indicated that the contribution of the didactic sequence for the teaching/learning of the subject proteins was positive, increasing the number of students modellers and enables them (a) increase the level of complexity and sophistication in their external representations (drawings and tactile models) and (b) the development and clarification of concepts not previously understood.