
A Ngram view of "moral philosophy", which seems to be on the rise going into the 21st century; which can be contrasted with the Ngram for "moral science", which is has petered out.

A Ngram view of "moral philosophy", which seems to be on the rise going into the 21st century; which can be contrasted with the Ngram for "moral science", which is has petered out.

In philosophy, moral philosophy refers to the study of philosophies concerning the nature of morals, i.e. theories or speculations about what is moral and or immoral; the study of the works and ideas of moral philosophers, e.g. Plato, Aristotle, Stoics, e.g. Zeno of Citium (see: slave stealing parable), Epicureans (Epicurus), Thomas Hobbes, Adam Smith, among others (Maxwell, 1850).

Overview
In 1849, James Froude's Nemesis of Faith was publicly burned during reverend William Sewells’ moral philosophy class at Oxford

In 1850, James Maxwell began corresponding with Lewis Campbell, about the nature of the soul (see: Maxwell on the soul), and related ideas, amid taking a moral philosophy class, at the University of Edinburgh, taught by John Wilson.

Thermodynamics
In Mar 2019, the fourth Google Scholar search return for keys: “thermodynamics, philosophy, morality” is the book Elements of Moral Philosophy, by Stuart Rachels and James Rachels, in which the key “thermodynamics” is used one time, as follows:

“The point of this book [on moral philosophy] is not to provide a neat, unified account of "the truth" about ethics. That would be a poor way to introduce the subject. Philosophy is not like physics. In physics, there is a large body of established truth that beginners must patiently master. (Physics teachers rarely invite their students to make up their own minds about the laws of thermodynamics). There are, of course, unresolved controversies in physics, but these take place against a background of broad agreement. In philosophy, by contrast, everything is controversial—or almost everything. Some of the fundamental issues are still up for grabs. A good introduction will not try to hide that somewhat embarrassing fact.”
— Stuart Rachels (2012), “Preface” (pdf) to The Elements of Moral Philosophy [2]

While theories such as Immanuel Kant's categorical imperative, there is no concordant discussion of Wilhelm Ostwald's 1901 energetic imperative, Bruce Lindsay's c.1959 thermodynamic imperative stylized physics lectures, or other historical moral theory logic based on thermodynamics, e.g. entropy ethics, only evidences two cultures disparity.

Quotes
The following are related quotes:

“Moral philosophy is nothing else but the science of what is good and evil, in the conversation, and society of mankind. Good and evil are names that signify our appetites, and aversions; which in different tempers, customs, and doctrines of men, are different: and diverse men, differ not only in their judgment, on the senses of what is pleasant and unpleasant to the taste, smell, hearing, touch, and sight; but also of what is conformable or disagreeable to reason, in the actions of common life.”
— Thomas Hobbes (1651), Leviathan [1]

“Changes in entropy can be used as a starting point to conceptualize the most accurate of ethical frameworks.”
— LackJester (2015), r/Philosophy Reddit post (Ѻ) to “Review of Jim Holt’s Why Does the World Exist?”

“I still haven’t met someone who understands what I mean when I say my morals and my beliefs align with the laws of thermodynamics. And no, I don’t mean those weird debates about thermodynamics proving the existence of god. I mean using entropy and enthalpy as a way to perceive the world and people beyond [status quo] science.”
— @SoftWeonwoo (2018), Tweet, Jul 28 [3]