A cause, in its widest application, can be defined as a positive principle from which something really proceeds with dependence in existence. This has significantly greater application than modern conceptions of causality, as shall become evident. In order to understand a thing through its definition, we need to be familiar with each of the notes in that definition. Hence, we examine each part separately.
A principle is that from which something proceeds in any way whatsoever. According as there are two kinds of orders, scil., the order which depends upon the mind (the order of reason) and the order which doesn’t depend on the mind (the order of reality) there are two kinds of procession: 1) procession according to the intellect; 2) procession according to reality. An intellectual principle is that from which something proceeds according to the order of knowing. In this way, the premises are the principle of the conclusion, not because the truth of the conclusion in reality depends upon the premises, but because our knowledge of the truth of the conclusion depends upon our knowledge of the premises. Thus, the premises of an argument are always logical causes of the truth stated in the conclusion, though not always real causes of the truth. For example, judging that a certain chemical reaction is present in some phenomenon is a principle of our knowing that this phenomenon contains chemical X; though, in reality chemical X is the cause of the reaction and not vice versa.
A real principle is that from which something proceeds according to reality. Thus, the real principle of the chemical reaction is chemical X. It should also be noted that, psychologically speaking, premises of the conclusion are also principles according to reality in the case of demonstration: our assents to the premises are the real cause of our assenting to the conclusion. Likewise, in dialectical argument, the form of the premises may be the real psychological principle of our enunciating the conclusion, though not to our assent (assent to a dialectical conclusion involves an act of the will).
A real principle may be one of two kinds: negative or positive. A negative principle is the absence of some form or perfection which precedes the presence of that form. Thus, in vivification (if indeed there is such a thing) non-living is the principle of life, though non-life is not a positive entity—it is the lack of a positive entity which might be there.
A positive principle is of two kinds: a principle of existence and not a principle of existence. A real principle which does not influence existence is a principle of mere quantitative succession: thus one point of quantity is a principle of the rest of the continuum; the beginning place of my motion is the principle of my motion, though it does not cause my motion; one is the principle of number; even principles of time (e.g., yesterday is the principle of today) are included in this quantitative kind of principle since time is the numbering of motion. Among this kind of principle we include necessary conditions; i.e., principles which are not the cause of a thing but which are dispositions required for a thing to exercise its causality. Thus, my living room window is a principle of illumination, but it does not cause light.
A positive principle of existence can be one of two kinds: a principle or existence upon which a thing depends for its existence, and a principle of existence upon which a thing does not depend for its existence. The first kind is the most familiar to us; the latter is an analogous principle known to us only by a positivo-negative concept—a negation of the first kind—and is for the consideration of Theology: e.g., the Son proceeds from the Father.
The first kind, a principle upon which a thing depends for existence, is a cause. This dependence is founded on 1) a real distinction between the existence of that which depends and the existence of that upon which it depends; 2) an imperfection in the being of the dependent thing. Neither of these pertain to God and, therefore, cause cannot be said of God. The procession in God is properly a relation of opposition which, as Metaphysics proves, implies no imperfection nor real distinction in existence.
More to come…