(a) By belief or faith is sometimes meant reason as distinguished from understanding, and sometimes reason as distinguished from reasoning. These two senses are so very closely allied that we may allow them to count as but a single signification. It is extraordinary that in either sense belief should be contrasted with reason, as it is by those who tell us that the infinite is an object only of faith, and that reason has to do exclusively with the finite, or that first principles are inaccessible to reason but revealed to faith. To create an appearance of conflict between reason and faith by identifying faith with reason in a special sense, and reason with understanding or reasoning, is unwarranted, if not puerile. What use can there be in telling us that God cannot be known—cannot be apprehended by reason—but is only an object of faith, a Being merely to be believed in, when what is meant is that we have the same immediate certainty of His existence as of the truth of an axiom of geometry?
(b) Belief may be limited to apprehension, and knowledge to comprehension. It may be said that "we have but faith, we cannot know" the unseen and infinite, just as it is said that we believe that the grass grows but do not know how it grows. It is obvious, however, that if apprehension be knowledge, as it surely is, we believe only what we know. We know—i.e., apprehend—the existence of God and the growth of the grass, and we believe what we thus know. We do not know—i.e., comprehend—the nature of God or the nature of growth, and what we do not thus know neither do we believe.
(c) At other times faith or belief relates to probable, as opposed to certain, knowledge. "We do not know this, but we believe it," often means, "We are not sure of this, but we think it likely." It is not in this sense, of course, that any one except a religious sceptic will allow that the existence of God is a matter of faith. A man may admit that religion and science differ as faith and knowledge, but if he is willing to understand this as signifying that while science is certain, religion is at the most merely probable, he must necessarily be a doubter or an unbeliever.
(d) Faith or belief sometimes refers to the knowledge which rests on personal testimony, Divine or human. Such faith may be more certain than assent given to the evidence furnished by science. It ought to be precisely proportioned to the evidence that there is such and such testimony, and that the testimony is trustworthy.
(e) By faith or belief is sometimes meant trust in a person or fidelity to a truth; the yielding up of the heart and life to the object of faith. Faith or belief of this kind always involves "preparedness to act upon what we affirm." It does not appear to me that such preparedness is, as Professor Bain maintains, "the genuine, unmistakable criterion of belief" in general. This kind of faith, like all other faith, ought to rest on the assent of the intellect to evidence, although what is characteristic of it is to be found not in the intellect but in the emotions and will. Since it constitutes and produces, however, spiritual experience, it is a condition and source as well as a consequence of knowledge. There can be, in fact, no profound religious knowledge, because there can be no vital religion, without it.
In religion, as in every other department of thought and life, man is bound to regulate his belief by the simple but comprehensive principle that evidence is the measure of assent. Disbelief ought to be regulated by the same principle, for disbelief is belief; not the opposite of belief, but belief of the opposite. Unbelief is the opposite both of belief and disbelief. Ignorance is to unbelief what knowledge is to belief or disbelief. The whole duty of man as to belief is to believe and disbelieve according to evidence, and neither to believe nor disbelieve when evidence fails him.
Note XI., page [118].
The Theological Inference from the Theory of Energy.