比較法是國內學界慣用的法學方法。學界對此方法的批評不絕如縷,但或許因為沒有提出明確的比較法的操作方法與理論基礎,並未動搖比較法的基本使用格局。運用法理學的思維工具,本文拆解比較法為兩大部分:借鏡應然價值、借鏡實然結果。本文主張,至少對理應促進法學理解的學術工作者,借鏡應然價值有三個步驟:(1)解析、萃取外國法(學)內含的價值理論;(2)探究該外國法(學)所內含之應然理論是否可採,若非完全可採,調整之;(3)在本國法之目的解釋步驟,套用前述應然理論,從其追求的價值出發,分析目的與手段關係,得出價值判斷所要求的特定規範內容。第一步是抽象化,第二步在同樣的抽象層次內分析,第三步則是具體化。當下學界不應繼續將外國法視為「認知權威」而不加調整,單純接受其價值。以比較法借鏡實然結果時,必須結合社會科學方法,運用恰當的研究設計作兩重因果推理,而非單憑直覺推斷。兩重因果推理的第一重理想上是實證研究,而第二重則是實然的理論推衍。主流的比較法論述習於自特定大陸法系國家取經,本文分析顯示:法系異同對借鏡價值或實然結果沒有必然的重要性。
Comparative law is a prevalent legal method. While it is subject to constant critiques, perhaps because no standard operating procedure or new theoretical foundation has been offered, comparative law studies are still conducted in the usual way. Using jurisprudential analytical tools, this article divides comparative law into two parts: borrowing normative values and borrowing positive outcomes. This article argues that, at least for academics whose jobs are to promote understanding of the legal system, the process of borrowing normative values should involve three steps: (1) distilling a normative theory from foreign law and jurisprudence; (2) explaining why the value judgments in the normative theory is desirable, and, if not, how to adjust; and (3) finally applying the (revised) normative theory in the interpretation of domestic laws, via the teleological interpretation approach. The third step includes analyzing the means-ends relationship and thus how best to achieve the normative goals. In short, the first step is abstraction, the second step is reasoning at the same abstract level, and the third step is concretization. Academics should no longer consider foreign law and jurisprudence as epistemic authority and accept them at face value. In addition, when borrowing positive outcomes, academics should use social-scientific methods in conducting double causal reasoning, rather than relying on their intuition. More specifically, the first causal reasoning is ideally empirical, whereas the second causal reasoning is positive and theoretical. The mainstream comparative law studies are accustomed to look at laws and jurisprudences from specific civil-law countries such as Germany, Japan, and France, while this article reveals that membership of legal families does not necessary matter when borrowing normative values and positive outcomes. Whether a foreign country's legal system is subject to a proper research design for causal reasoning and whether a foreign country's jurisprudence advances helpful normative discussions are more important for comparative purposes.