【「自然法則，無法則的自然：自成一體的古典世界」】演講側記

「自然法」是一種法律與哲學的概念，主張我們透過理性，可以發掘某些自然界固有的、且對全人類普遍適用的權利與道德原則。這個概念深刻地影響了我們如何理解正義、權利以及人類與自然界的關係。在他的演講中，Mantovani 教授帶著我們回到古希臘和古羅馬的世界，既追溯自然法的起源，也探討「自然」這一概念的發展。

從公元前 3 世紀至公元 4 世紀，羅馬的法學家們奠定了自然法的理論基礎。這些法學家的著作後來被編入查士丁尼皇帝的《法典》（Digest），並在中世紀時被重新發現，成為大學興起與歐洲普通法發展的知識根基。

那麼，對於古人來說，何謂「自然」呢？

Mantovani 教授解釋道，現在的人們將「自然」視為一種外在的、與自己分隔開來的存在，然而，對於古人來說，自然卻是一種內在的力量，一種引導我們達成自我實現的驅動力。教授提醒我們，為了尊重古典世界，我們應該回歸古代文獻，透過仔細閱讀去理解當時人們的想法。

羅馬學者將法律劃分為三大類：ius naturale（自然法）、ius gentium（萬國法）和 ius civile（市民法）。Ius naturale 指的是所有生命共通的本能與行為，ius gentium 則以理性作為出發點，普遍適用於人類的社會，而 ius civile 則是規範特定城市的法律制度。這種劃分法源自於斯多葛學派（Stoicism），將世界劃分為不同生命層級的思想。

自然法的概念將人類置於法律世界的中心，也因此形成了人類與其他生命之間的鴻溝。雖然動物和自然界被視為同屬一個宇宙，但它們往往被當作供人類利用和支配的對象。這種人類中心的觀點深刻塑造了西方的法律傳統，並且至今仍然是許多法律體系的核心價值，台灣的民法典也不例外。如此根深蒂固的觀點，已成為隱形的框架，使得當今要在法律中納入非人類生命的權利變得極為困難。正如 Mantovani 教授所提點的，這種內建的人類中心主義，反而可能使自然法成為大自然最大的敵人。

然而，近年來，越來越多人開始認知到我們需要擴大法律權利的範疇，將其涵蓋至非人類的生命。某些新興的觀點，像是「自然契約」（“natural contract”）的概念，已逐漸受到重視。這個概念認為，人類應該透過法律框架，將動物、植物及生態系統視為擁有固有權利的法律主體，而不僅僅是財產的客體。在這種關係之下，我們才能夠與其他生命和諧共存。

古羅馬詩人和哲學家盧克萊修（Lucretius, c. 99 – c. 55 BC）在其名著《物性論》（De Rerum Natura, c. 1st century BC）中提到，生命從簡單的植物逐步演變至複雜的動物，最終演變為人類文明。對盧克萊修而言，變化是成長的動力。根據他的觀點，一般被我們馴養的動物（如狗、羊、牛⋯⋯），雖然本身不具有生存優勢，但對人類是「有用的」，得以存活下來。大自然將牠們置於人類的「管教」或保護之下，以換取牠們的效用。然而，正如Mantovani教授所指出的，動物無法為自己發聲，因此這種模式仍存在著上對下的關係。將這種關係稱為「自然契約」，並用此作為現有法律架構的依據，無疑是不尊重且濫用古代思想的表現。

總結來說，Mantovani 教授提醒我們，在解讀古代文獻時，必須保持謹慎。我們不能將古代的思想用來正當化現代的意識形態，或是強化以人類為中心的法律框架，無條件赦免人類的種種作為。相反的，透過融合古今智慧，我們可以開始建立一個尊重所有生命形態的法律體系。在這個過程中，我們不僅能夠更深入地了解自我，還能夠更加地自我提升。

“Natural law” is the legal and philosophical concept that certain rights and moral principles are inherent in nature, discoverable through reason, and universal to all humans. This concept has profoundly shaped how societies understand justice, rights, and the relationship between humans and the natural world. In his lecture, Professor Mantovani invites us to journey back to the ancient worlds of Greece and Rome, tracing not only the origins of natural law but also the very concept of “nature” itself.

The foundations of natural law were laid by Roman jurists from the 3rd century BCE to the 4th century AD. The writings of these jurists, later compiled in Emperor Justinian’s Digest, were rediscovered during the Middle Ages, providing the intellectual foundation for the rise of universities and the development of European law.

But what was “nature” to the ancients? 

While we today tend to see nature as something external—something separate from us—Professor Mantovani explains that the ancients viewed nature as something internal: an inner driving force that guides us to become what we should become. To honor this ancient world, says Professor Mantovani, we must go back to the texts of antiquity and engage in close readings to uncover the ideas they contain.

Roman scholars divided the law into three categories: ius naturale (natural law), ius gentium (law of nations), and ius civile (civil law). This division can be understood through the lens of the Stoic conception of the “scale of being.” Ius naturale refers to the basic, instinctual behaviors shared by all living creatures, while ius gentium is based on human reason and applied universally across societies, and ius civile governs the specific legal systems of individual cities.

This system placed humans at the center of the legal universe, creating a deep divide between mankind and all other living creatures. Animals and the natural world, although seen as part of the same cosmos, were viewed primarily as objects to be used or controlled by humans. This anthropocentric perspective shaped Western legal traditions and remains a defining feature of many modern legal systems, including Taiwan’s civil code. So ingrained is this perspective that it has become almost invisible, making it exceedingly difficult to create laws today that include non-human beings. As Professor Mantovani warns, this entrenched anthropocentrism may, in fact, make natural law come perilously close to becoming the worst enemy of nature.

In recent decades, however, there has been growing interest in expanding the concept of legal rights to include non-human entities. One idea gaining traction is the concept of a “natural contract.” According to this idea, humans should live in harmony with the rest of the world through a legal framework that treats animals, plants, and ecosystems as legal subjects with inherent rights, not merely as objects of property.

The ancient Roman poet and philosopher Lucretius (c. 99 – c. 55 BC), in De Rerum Natura (c. 1st century BC), argued that life evolved from simple plants to complex animals, culminating in human civilization. Change, to Lucretius, is the necessary impetus of growth. According to Lucretius, domesticated animals (e.g. dogs, sheep, oxen…) were able to survive, despite their weakness, because of their usefulness to human beings. In exchange for their utility, they were placed by nature under the “tutelage,” or protection, of mankind. However, animals, as Professor Mantovani points out, cannot speak for themselves and are thus not on equal footing with humans. To call this arrangement a “natural contract” and use it to justify current legal frameworks would be a disrespectful misuse of antiquity.

In conclusion, Professor Mantovani urges us to be cautious in our interpretation of ancient texts. We must avoid using them to support modern political agendas that reinforce a legal hierarchy, justifying our right to treat animals with impunity. Instead, by integrating the lessons of both antiquity and the present, we can begin to forge a legal framework that respects all forms of life, not just human life. In the process, we can not only get to know ourselves better, but also make ourselves better in the future.