Explanandum and explanans

Explanandum and explanans are two critical concepts in the philosophy of science, particularly within the context of scientific explanation. The explanandum is the phenomenon or event that needs to be explained, while the explanans comprises the statements or group of statements that provide the explanation for the phenomenon. Understanding the relationship between explanandum and explanans is essential for evaluating the adequacy of scientific theories and models.

Explanandum

The explanandum is the "what" in the question of "what is being explained?". It is the statement that describes the phenomenon or event for which an explanation is sought. In scientific research, identifying the explanandum is the first step in the process of inquiry. It sets the stage for investigation and guides the direction of the research. The explanandum can be anything from a specific observation, such as the orbit of a planet, to a broader phenomenon, such as the patterns of biodiversity.

Explanans

The explanans, on the other hand, is the "how" or "why" in the explanation. It consists of a set of statements or laws, combined with specific conditions, that together account for the explanandum. The explanans must have empirical content; that is, it must be testable through observation or experiment. It often includes laws of nature, initial conditions, and other relevant facts that, when taken together, logically lead to the explanandum. The quality of an explanans is judged by its ability to provide a coherent, comprehensive, and parsimonious explanation of the explanandum.

Types of Explanations

There are several types of explanations in science, each with its own approach to linking explanans to explanandum. These include:

• Deductive-Nomological (D-N) Explanation: This type of explanation involves deducing the occurrence of the explanandum from general laws and specific initial conditions. It is often associated with the work of Carl Hempel and is also known as the covering law model.

• Inductive-Statistical (I-S) Explanation: Unlike D-N explanations, I-S explanations involve statistical laws. The explanans provides a probabilistic account of why the explanandum occurred.

• Causal Explanation: This approach focuses on identifying the causes of the explanandum. It involves tracing the causal chain that leads to the occurrence of the phenomenon.

• Functional Explanation: Particularly common in biology and social sciences, functional explanations account for the explanandum by elucidating the role or function it serves within a system.

Challenges and Criticisms

The concepts of explanandum and explanans, while foundational to scientific inquiry, are not without their challenges and criticisms. One major challenge is the problem of underdetermination, where multiple, equally valid explanans can be proposed for the same explanandum. Additionally, the subjective nature of determining what constitutes an adequate explanation can lead to disagreements within the scientific community.

Conclusion

The interplay between explanandum and explanans is at the heart of scientific explanation. By carefully delineating what needs to be explained and proposing a set of statements that can account for it, scientists can deepen our understanding of the natural world. Despite the challenges inherent in this process, the pursuit of clear and compelling explanations remains a central endeavor of scientific inquiry.