Of the distinction of natural and moral Necessity, and Inability.
The Necessity which has been explained above can be distinguished into more and natural Necessity. I will not delve into whether this distinction is a perfect one, but this is how the terms are understood and it is how I will use them below.
Moral Necessity is used in different ways. We use it to mean the Necessity of moral obligation, as when a person “is under bonds and duty of conscience from which he cannot be discharged.” Sometimes moral Necessity refers to “that Necessity of connexion and consequence” that arises from moral causes, such as the strength of inclination or motives, and the connections between those and “such certain volitions and actions. This is the sense in which I will be using the phrase “moral necessity.”
As applied to men, I define natural necessity as the Necessity we are “under through the force of natural causes” as opposed to moral causes, e.g., “habits and dispositions of the heart, and moral motives and inducements.” Thus, in certain situations, men experience particular things by Necessity: “they feel pain when their bodies are wounded;” they see things in a clear light when their eyes are opened; they acknowledge a truth as soon as they understand the terms (such as 2+2=4 or that parallel lines never intersect); “so by a natural Necessity men’s bodies move downwards, when their is nothing to support them.”
Note the following things about these two kinds of Necessity:
1. “Moral Necessity may be as absolute as natural Necessity.” Moral cause and effect may be just as perfectly connected as any natural cause and effect. Regardless of whether the Will is always “necessarily determined by the strongest motive,” anyone would accept, I think, that in some cases the motive is so strong “that the act of the will may be certainly and indissolubly connected therewith.” When a motive or bias is very powerful, it is generally accepted that it is difficult to go against them (and the difficulty increases in direct proportion to the power of the motive). At a certain point, the difficulty could become so great as to be insurmountable. Men have some power to overcome difficulties, but that power is not infinite; rather it has limits. Because it must be allowed that there can be a perfect connection between moral cause and effect, “so this only is what I call by the name of moral Necessity.”
2. Just because I distinguish between these kinds of necessity (moral vs. natural), that does not mean that if something comes to pass by moral necessity, “the nature of things is not concerned in it. I do not mean to say that when an act of the Will “infallibly follows” an insurmountable motive, “this is not owing to the nature of things.” Nevertheless, “natural” and “moral” are how these two kinds of Necessity have usually been distinguished and they must be distinguished somehow because there is a difference between them that has important consequences. The difference consists more “in the two terms connected” than in the nature of the connection. The cause of the effect “is of a particular kind,” namely something of a moral nature, “some previous habitual disposition, or some motive exhibited to the understanding.” Likewise, the effect is something of a moral nature, some “volition of the soul, or voluntary action.”
I suppose that natural necessity is so called “because mere nature,” as that word is commonly used, is not concerned with choice. “Nature” is often used “in opposition to choice” not because nature never has anything to do with our choice, but probably because our first notion of nature comes from our observation of things in which our choice plays no part. This is especially true with respect to the material world, in which we easily perceive “a settled course” or “manner or succession.” However, where we do not easily recognize “the rule and connexion” (although the connection truly exists) we refer to that sort of thing as something other than “nature.” Even some things in the material world that do not obviously occur “according to any settled course” are not called “nature,” but rather accident, chance, contingence, etc. Men distinguish between nature and choice “as if they were completely and universally distinct.” But I suppose it must be acknowledged that in many cases choice “arises from nature, as truly as other events.” It is not always obvious, however, how acts of choice and their causes are connected “according to established laws.” Choice appears to us to be a departure from the established order of things, showing itself most obviously in “corporeal things.” Choice also tends to “alter the chance of events” and causes them to go forward differently that they would have if left alone. “Hence it is spoken of as if it were a principle or notion entirely distinct from nature and properly set in opposition to it.”
3. Note that in explaining my term “moral Necessity,” the word Necessity is not used in its “original design and meaning.” As explained already, terms such as necessary, impossible, etc., as commonly used, are always relative; they always assume some “voluntary opposition . . that is insufficient.” With moral Necessity, however, no such opposition can be assumed because it “is a certainty of the . . . will itself.” It is absurd to imagine an individual will opposing itself in its present act, just as it would be absurd “to talk of two contrary motions, in the same moving body, at the same time.”