This paper challenges the common assumption that some phenotypic traits are quantitative while others are qualitative. The distinction between these two kinds of traits is widely influential in biological and biomedical research as well as in scientific education and communication. This is probably due to both historical and epistemological reasons. However, the quantitative/qualitative distinction involves a variety of simplifications on the genetic causes of phenotypic variability and on the development of complex traits. Here, I examine three cases from the life sciences that show inconsistencies in the distinction: Mendelian traits (dwarfism and pigmentation in plant and animal models), Mendelian diseases (phenylketonuria), and polygenic mental disorders (schizophrenia). I show that these traits can be framed both quantitatively and qualitatively depending, for instance, on the methods through which they are investigated and on specific epistemic purposes (e.g., clinical diagnosis versus causal explanation). This suggests that the received view of quantitative and qualitative traits has a limited heuristic power—limited to some local contexts or to the specific methodologies adopted. Throughout the paper, I provide directions for framing phenotypes beyond the quantitative/qualitative distinction. I conclude by pointing at the necessity of developing a principled characterisation of what phenotypic traits, in general, are.

中文翻译：

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超越数量和质量特征：生命科学中的三个案例

本文挑战了一些表型性状是定量的而另一些是定性的常见假设。这两种特征的区别在生物学和生物医学研究以及科学教育和传播中具有广泛的影响。这可能是由于历史和认识论的原因。然而，定量/定性区分涉及对表型变异的遗传原因和复杂性状发展的各种简化。在这里，我检查了生命科学中显示出不一致的三个案例：孟德尔特征（植物和动物模型中的侏儒症和色素沉着）、孟德尔疾病（苯丙酮尿症）和多基因精神障碍（精神分裂症）。我表明，这些特征可以定量和定性地构建，这取决于例如研究它们的方法和特定的认知目的（例如，临床诊断与因果解释）。这表明，公认的数量和质量特征的观点具有有限的启发能力——仅限于某些当地环境或所采用的特定方法。在整篇论文中，我提供了在定量/定性区别之外构建表型的方向。最后，我指出有必要对一般的表型特征进行原则性的表征。这表明，公认的数量和质量特征的观点具有有限的启发能力——仅限于某些当地环境或所采用的特定方法。在整篇论文中，我提供了在定量/定性区别之外构建表型的方向。最后，我指出有必要对一般的表型特征进行原则性的表征。这表明，公认的数量和质量特征的观点具有有限的启发能力——仅限于某些当地环境或所采用的特定方法。在整篇论文中，我提供了在定量/定性区别之外构建表型的方向。最后，我指出有必要对一般的表型特征进行原则性的表征。