論理

1. Origins, structure, and basic meaning

• Structure: 論理（ろんり） means the reasoning or structure of thought connecting claims and explanations.
• Basic usage: 説明の論理 concerns how ideas connect within an explanation; 論理に基づいて判断した describes a decision based on that reasoning.

2. Common pitfalls and similar expressions

• A reason versus a line of reasoning
  • 理由 focuses on why a decision or action was taken. 論理 focuses on how grounds and conclusions connect, so the two are not always interchangeable.
• Reasoning contrasted with emotion
  • In the example, 感情だけでなく論理に基づいて means using reasoning as well, rather than emotion alone, as a basis for judgment. It does not describe a complete absence of emotion.