Aristotelian Foundations of Legal Theory and Methodology

Defining Legal Rules: An Aristotelian Perspective

A primary perspective of a legal rule can be obtained from its definition, provided by the Aristotelian-scholastic mold. The definition represents the expression of the essence of a thing and should include an indication of the general category to which it belongs, in addition to the features that distinguish it from other realities within the same category.

Systematic Frameworks in Legal Institutions

Facing a legal institution through its definition contributes to framing it within a systematic, "regional" context. The definition involves the formation of generic concepts—such as legal relationships or legal business—which were unknown to Roman dogmatics, where legal concepts were often treated in isolation. Conversely, this relational approach exposes similarities and differences, allowing for the identification of sub-genres.

The Four Causes in Legal Analysis

Aristotle distinguished between four types of causes:

• Material cause: The substance.
• Formal cause: The existence or differentia.
• Efficient cause: The genetic element.
• Final cause: The purpose.

Once the material cause is equated to the genus and the formal cause to the differentia, the remaining perspectives are those of the efficient and final causes. Even when it is not possible to link legal institutes through their essence, they can often be connected by the factors that gave rise to them (efficient cause) or their intended purpose (final cause).

Dialectical Processes and Legal Comparison

Many relationships between legal figures are achievable through comparison and dialectical processes. Often, these comparisons rely on the locus a definitione or a causis. Furthermore, comparison facilitates the use of arguments such as:

• Parity of reason: Establishing consistency.
• Majority of reason by analogy: Serving as a unifying factor for legal regulation and the resolution of policy contradictions within the same legal order.

The Role of Legal Authority

Another perspective for legal knowledge involves addressing institutions and figures through the lens of established authorities. In a field where truth is often only probable, the most widely accepted opinion is considered the most likely to be true. Consequently, lawyers—in their efforts to update and systematize the law—have historically relied not only on primary legal texts but also on the commentaries of the most authoritative legal scholars.