If an organic chemistry student explains that she represents a mechanistic step because “it's a productive part of the mechanism,” what meaning could the professor teaching the class attribute to this statement, what is actually communicated, and what does it mean for the student? The professor might think that the explanation is based on knowledge of equilibria of alternative steps. The professor might also assume that the student implies information about how one of the alternatives influences the energetics of subsequent steps or how subsequent steps influence the equilibria of the alternatives. Meanwhile, the student might literally mean that the step is represented simply because it leads to the product. Reasoning about energetic influences has much greater explanatory power than teleological reasoning taking the consequence of mechanistic steps as the reason for their prediction. In both cases, however, the same backward-oriented reasoning is applied. Information about subsequent parts in the mechanism is used to make a decision about prior parts. To qualitatively compare the reasoning patterns and the causality employed by students and expected by their professor, we used a mechanistic approach from philosophy of science that mirrors the directionality of a mechanism and its components: activities, entities, and their properties. Our analysis led to the identification of different reasoning patterns involving backward-oriented reasoning. Participants' use of properties gave additional insight into the students' reasoning and their professor's expectations, which supports the necessity for clear expectations in mechanistic reasoning in organic chemistry classrooms. We present a framework that offers a lens to clarify these expectations and discuss implications of the framework for improving student mechanistic reasoning in organic chemistry.

中文翻译：

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这个机械步骤是“富有成效的”：有机化学专业学生的后向推理

如果有机化学专业的学生解释说她代表机械步骤，因为“这是该机制的重要组成部分”，教授课堂教学的教授将这句话归于什么意思，实际上传达了什么，对学生意味着什么？教授可能会认为，解释是基于替代步骤的平衡知识。教授可能还假设学生暗示有关替代方案之一如何影响后续步骤的能量或后续步骤如何影响替代方案的平衡的信息。同时，学生可能从字面上讲是表示该步骤仅是因为它导致了产品。关于能量影响的推理比以机械步骤的结果作为其预测原因的目的论推理具有更大的解释力。但是，在两种情况下，都应用相同的后向推理。有关该机制中后续部分的信息用于做出有关先前部分的决策。为了定性地比较学生使用的和教授期望的推理模式和因果关系，我们使用了一种科学哲学的机制方法，该方法反映了一种机制及其组成部分的方向性：活动，实体及其属性。我们的分析导致确定了涉及向后推理的不同推理模式。参与者对属性的使用使学生对推理和他们的教授的期望有了更多的了解，这支持在有机化学教室中对机械推理提出明确期望的必要性。