Besides this, one can, as a separate undertaking, show these people later the way of reasoning about these things. In this metaphysics, it will be useful for there to be added here and there the authoritative utterances of great men, who have reasoned in a similar way; especially when these utterances contain something that seems to have some possible relevance to the illustration of a view. (13) By contrast, Mercer uses Leibniz's Rhetoric of Attraction to explain the discrepancies between different descriptions of his intellectual evolution and philosophical system, statements that ultimately served to "lead wayward souls to the philosophical truth" (2001, p. 37). Consequently, Mercer regards Leibniz as a "conciliatory eclectic par excellence," who was one of a group of teachers and scholars with whom he worked early in his intellectual career, from 1661-68.

Hassing notes that Jakob Thomasius was Leibnez's primary inspiration; however, Johann Adam Scherzer, Johann Christoph Sturm, and Erhard Weigel at Leipzig and Jena were influential as well. In fact, in Leibniz, the term "system" assumes a new connotation: "One can rightly speak of the Cartesian system in the sense of a whole whose parts are interdependent for their intelligibility, or of Aristotle's system, although in a looser sense, owing to the heterogeneity of the Aristotelian sciences" (Hassing, 2003, p. 721). Hassing suggests that in Leibniz, though, "system" actually means bringing together opposing accounts that had previously irreconcilable. "Consider Leibniz's extraordinary (attempted) reconciliations and harmonizations: Plato and Aristotle, Aristotle and the mechanists, Catholic and Protestant, Christianity and freethinking, East and West, the goodness of God and the evil of the world" (2003, p. 722).

Immanuel Kant. Rather than depending on a spiritual divinity as the source of morality, Immanuel Kant relied on a "categorical imperative" that was an absolute framework that brooked no qualifications whatsoever. Kant's view was that an individual should not act because of the motives specified by the theologians; rather, people must obey moral rules just because it is the right thing to do, and only then can people be said to be truly morally right. In his analysis of Kant and the exact sciences, Michael Friedman (1992) suggests that "much of Kant's philosophical development can be understood... As a continuous attempt to construct... A genuine metaphysical foundation for Newtonian natural philosophy" (p. 4). De Jong (1995) reports that Immanuel Kant began his philosophical career as an advocate of what was previously known as "Leibnizian-Wolffian metaphysics"; however, Kant became increasingly less convinced of the possibility of reconciling this metaphysics with the exact sciences of his day. Kant also believed that the metaphysical methodology should follow that of Isaac Newton (whom he also greatly admired): "The true method of metaphysics is basically the same as that introduced by Newton into natural science and which has been of such benefit to it" (in De Jong, p. 40).

In Kant's Prolegomena to Any Future Metaphysics That Will Be Able to Present Itself as a Science, he says, "My purpose is to convince all those who find it worth their while to occupy themselves with metaphysics: that it is absolutely necessary to suspend their work for the present, to regard everything that has happened hitherto as not having happened, and before all else first to raise the question: 'whether such a thing as metaphysics is possible at all'" (Kant, 1953, p. 3). On the one hand, Kant wondered, "If it is a science, how does it come about that it cannot establish itself, like other sciences, in universal and lasting esteem?"; on the other hand, "If it is not, how does it happen that under the semblance of a science it ceaselessly gives itself airs and keeps the human understanding in suspense with hopes that never fade and are never fulfilled?" (Kant, p. 4). To help solve this philosophical quagmire, Kant proposed an ethical system based on a belief that the reason is the final authority for morality.

According to Kant, moral truths are not received from divine sources or inspiration; instead, such moral truths are based on reasons that make sense to all people (in fact, all rational beings) who spend the time necessary to think about them in the first place. Kant says that his work, Groundwork for the Metaphysics of Morals, was "intended for nothing more than seeking out and establishing the supreme principle of morality." In this regard, Kant states...

we find that the more a cultivated reason applies itself with deliberate purpose to the enjoyment of life and happiness, so much the more does the man fail of true satisfaction.... And they end by envying, rather than despising, the more common stamp of men who keep closer to the guidance of mere instinct and do not allow their reason much influence on their conduct," a concept that brings the discussion to Kant's first proposition, "Duty."
The First Proposition - Duty. Kant uses reason to examine reason to determine what duties are required to ensure behaviors are moral. According to Kant, "For as reason is not competent to guide the will with certainty in regard to its objects and the satisfaction of all our wants, this being an end to which an implanted instinct would have led with much greater certainty; and since, nevertheless, reason is imparted to us as a practical faculty,... its true destination must be to produce a will, not merely good as a means to something else, but good in itself, for which reason was absolutely necessary." Further, Kant suggests that the concept of duty must be differentiated from inclinations because the motivation for the behaviors may affect the morality of the behavior; Kant says that duties include that of having a "good will"; however, this also suggests that there are certain "subjective restrictions and hindrances." Other duties include maintaining one's own life, being beneficent whenever possible, and to secure one's own happiness.

Duty and Moral Worth. Kant's second proposition is:

That an action done from duty derives its moral worth, not from the purpose which is to be attained by it, but from the maxim by which it is determined, and therefore does not depend on the realization of the object of the action, but merely on the principle of volition by which the action has taken place, without regard to any object of desire."

Third Proposition -- Duty and the Respect for the Law. Kant maintained that actions of any sort must be undertaken from a sense of duty dictated by reason, and no action performed for expediency or solely in obedience to law or custom can be regarded as somehow being "moral." Kant says his third proposition is a consequence of the first two: "I would express thus Duty is the necessity of acting from respect for the law.... But I cannot have respect for it, just for this reason, that it is an effect and not an energy of will."

The Categorical Imperative. Kant's "categorical imperative" is an absolute framework that allows no qualifications whatsoever. According to Kant, humanity does not actually require science and philosophy to know what should be done in order to be honest and good:.".. Yea, even wise and virtuous. Indeed we might well have conjectured beforehand that the knowledge of what every man is bound to do, and therefore also to know, would be within the reach of every man, even the commonest."

In this regard, Kant succeeds in providing an exhaustive assessment of what roles reason and duty play in developing moral concepts in mankind:

Whether we demonstrate our knowledge or our ignorance, something certain must at last be settled about the nature of this would-be science; for things cannot possibly go on any longer on their present footing. It seems almost ridiculous, while every other science makes ceaseless progress, to be constantly turning round on the same spot without moving a step forward in the one that claims to be wisdom itself and whose oracle everyone consults. Also it has lost a great many of its supporters, and we do not see those who feel themselves strong enough to shine in other sciences wanting to risk their reputation in this one, in which everyone who is ignorant in all other things arrogates to himself a decisive judgment; for there is in fact no sure weight and measure as yet in this territory with which to distinguish soundness from shallow chatter. (Kant, 2003 ed., p. 4).

Kant maintains that actions are moral if and only if they are undertaken for the sake of morality in and of itself, in other words, people are not moral if they bring an ulterior motive to the rationalization process. As a result, the moral quality of an action must be measured not according to the action's consequences, but according to the motive that produced it in the first place. Kant also believed that actions are only moral if they are undertaken out of respect for the moral law (as opposed to some other type of motivation such as an individual need or…