I. Mathematical Reasoning Cannot be Analysed by Traditional Syllogistics.- II. The Psychological Interpretation of Mathematical Reasoning.- III. The Logicist Tradition.- IV. Strict Demonstration and Heuristic Procedures.- V. Intuitive Structures and Formalised Mathematics.- VI. "Thinking Machines" and Mathematical Thought.- VII. Lessons of the:History of the Relations Between Logic and Psychology.- VIII. General Psychological Problems of Logico-Mathematical Thought.- IX. General Psychological Problems of Logico-Mathematical Thought (Continued).- X. The Psychological Problems of "Pure" Thought.- XI. Some Convergences Between Formal and Genetic Analyses.- XII. Epistemological Problems with Logical and Psychological Relevance.- General Conclusions.- Name Index.