Hallo, this is Dr. Bin Song in the course of the History of Modern Philosophy at Washington College.

The first section of this course studies the great accomplishment of modern Western philosophy, the Enlightenment, and its broad social, political and religious implications. How can modern philosophers get there? To find the origin of the Enlightenment within the European thought itself, we have to track back to another phenomenon which, ever since its inception, has never stopped shaping and transforming human society. This is the so-called modern scientific revolution.

However, to understand why such a change of the fundamental way how humans pursue science and knowledge is called a “revolution,” we need to firstly understand what it is revolutionary against. In this regard, it would be necessary for us to canvass the most dominant philosophical view in medieval Europe, and in particular, the Aristotelian natural philosophy. In the first assigned video of this week’s learning, I gave a general introduction to Aristotle’s thought, including topics such as why Aristotle became the most impactful philosopher in Medieval Europe, Aristotle’s general method of doing philosophy, the relationship between Aristotelianism and Christianity, Aristotle’s thought in ethics, politics, etc. After this general introduction of Aristotelianism, let’s more intensively see into the aspect of Natural Philosophy, which, in the time of medieval Europe, was the prevalent name of what we now call “natural science.”

Overall, the world depicted by Aristotle’s natural philosophy, as mainly represented by his two books, the Physics and the On the Heavens, is closed, meaningful, but untrue, or at least shall we say, less true in comparison to what we humanity currently know about the natural world according to more advanced natural sciences. Let’s parse these three attributive adjectives one after another.

It is very obvious that the Aristotelian world is closed. It has a center of the universe, the earth; a hierarchical partition of the universe, the super-lunar and sub-lunar spheres; and most importantly, it has a closed border, and thus, as Aristotle forcefully argued in on the Heavens, the world is not infinite. Within this closed, finite world, each physical position “matters” in the sense that each of them is qualitatively different from another, and hence, each natural object (which is defined as those objects who have a principle of movement intrinsic to themselves such as fire, water, earth and air all being able to move by themselves without human interference) occupies a natural position belonging to itself, and once leaving this natural position, these objects will automatically tend to return back. From the center to the periphery of the universe, these so-called natural elements are the earth in the center, divine element or ether in the super-lunar sphere, and water, fire, air lying in between.

This world is closed not only in the depicted sense of the outside real world; regarding the use of human intelligence, Aristotle famously argued that because mathematics is about things that cannot move, physicists would only use mathematical thinking to a limited extent in their job, viz., observing and studying the empirically visible shape which natural objects move into. In this way, Aristotle refused to employ the full span of human reason in the matters of knowing the natural world. Therefore, his physics can be seen as a “common-sensical” theory which relies upon observing via human sense, and then, categorizing thus observed natural phenomena using the Aristotelian logic of syllogism, which is a logic constituted by categories of humans’ everyday language. In other words, the free, pure, and in a certain sense, separated-from-realities construction of human reason about mathematical objects such as geometrical shapes and their numerical features has never played a central role in Aristotle’s natural philosophy. Therefore, the first distinctive feature of Aristotle’s natural philosophy, in comparison with modern ones, is its closed worldview in tandem with a tamed use of human intelligence.

Secondly, the world of Aristotle is utterly meaningful, because everyone who studies the natural world using the method of Aristotle will readily find a guidance of human life, and therefore, they would not feel lost, as modern people normally did, in such a natural world which is full of facts, but also thought of by Aristotle as having an intrinsic connection to the moral values of human life. Quite often, modern people need to figure out the meaning of their life individually, and they cannot easily find a common, “natural” platform to anchor and share their individual interpretations of the meaning of life with others. In this respect, we have to affirm comparatively that the Aristotelian world feels more secured for human beings.
In more concrete terms, the meaning of Aristotle’s world comprises three aspects:

• 1) The super-lunar world comprises divine elements that are thought of as being eternal, non-generated, and hence, absolutely perfect. Aristotle also thinks consequently that this is the part of world where gods and deities would like to dwell. Since there is a part of the world where gods reside, humans would become naturally a worshiper or believer whenever they raise their heads and gaze at the sky.
• 2) Every object in the sub-lunar world has an “end” to move into, viz. the natural position of each material element or the full-grown shape of a living being. This end is thought of as being the best that an object can acquire given all changes and vicissitudes that they may endure during the time of their preservation. And these first two points lead to the third most powerful one which answers in an Aristotelian way why and how human life can become meaningful.
• 3) The ultimate reality that constantly produces and renews the entire orderly world, in the final analysis of Aristotle’s thought, is Nous, an all-pervading, self-creating, and self-regulating energy field. Through contemplating the order and wonder in such a closed, yet magnificent world, Humans are trying to be Nous-like so as to fulfill the most flourished form of human life as distinguished from other species on the earth, which is called “Eudaimonia,” human happiness. Therefore, according to Aristotle, to be a natural scientist is to seek happiness, not only in the intellectual sense of fulfilling one’s curiosity, but also to realize the most noble and desirable way of human life so as to manifest the best of humanity.

Unfortunately, the third feature of Aristotle’s natural philosophy is that despite being orderly, closed and ultimately meaningful, it is by and large untrue.

Firstly, there are intrinsic problems that cannot be answered well by the system itself. For instance, how to explain an object thrown on the top of a mountain moves in the shape of a parabola is a very difficult issue for Aristotle. On the one hand, according to Aristotle’s general principles of physics, a heavy body is supposed to move straightly towards the center of the earth unless there is an external force to compel the object away from its natural trajectory; however, since the thrown object is moving in the air, it is just so hard for Aristotle and natural philosophers after him to discover, or even conceptualize the external force. This issue would be eventually solved by Galileo when he abandoned the qualitative framework of Aristotelian physics, and turned to the pure quantitative features of natural movement to say that the parabola is a just combination of two dimensions of the same thrown object’s movement, a horizontal one and a downward one. However, when Galileo did so, he is not to amend defects of Aristotelianism using Aristotle’s own terms; instead, it is a total abandon of the entire framework of Aristotle’s natural philosophy. Therefore, we characterize Galileo’s science as a revolution, rather than a reformation.

Secondly, new natural phenomena were continually observed by scientists towards the end of the medieval time, and this created two touchy problems for the old Aristotelian natural philosophy from outside.

• 1) More “natural positions” need to be assigned to these natural phenomena so as to mark their “orderliness” or normalcy within an already very ordered world. But this will inevitably increase terms and languages used to label and describe these new natural positions. Since Aristotle never intended to deduce diverse phenomena from limited numbers of physical principles just like Euclid did in his geometry, the Aristotelian natural philosophy became accordingly more and more wordy, burdensome, and eventually, tediously boring. As we will discuss in the future, the lack of aesthetic appeal of the old Aristotelian natural philosophy became a motivation for scientists’ new endeavors in early modern Europe.
• 2) New observations constantly defied against the descriptions given by Aristotle. For instance, Aristotle said the super-lunar world is eternal and perfect, but Galileo found black spots on the sun, and desolate crater mountains on the moon using his telescope which make the heavenly world look less likely to be a place for gods to dwell in.

However, even if the Aristotelian natural philosophy became less and less true towards the end of medieval Europe, its final defeat by modern scientists has taken more than 200 years from the time of Copernicus to Newton. After all, its closed nature of meaningfulness was so intertwined with the dominant Christian worldview that had furthermore broadly and minutely connected to every aspect of human life in that particular period of history. Humans felt safe, found comfort, and enjoyed the meaning of this old worldview for so long a time, that we can anticipate that any significant change of it would have generated a great amount of discomfort, agony, and even social turmoil. However, can we affirm with a 100% of confidence that the modern worldview that has completely replaced Aristotle’s old one is absolutely true? This modern worldview, as we shall closely examine later, is open, truer, but hardly said to be meaningful in comparison to Aristotle’s. If this is the case, isn’t it a secured vision that we can learn a great deal from the transformation of Aristotelianism to Newtonianism since perhaps, and just perhaps, we will experience similar transformations in the future of human history again? I hope my lecture on Aristotle so far has simulated your great thoughts on these questions.