"It is, we are told, the special peculiarity of the devil that he was a liar from the beginning. If we set out in life with pretending to know that which we do not know; with professing to accept for proof evidence which we are well aware is inadequate; with wilfully shutting our eyes and our ears to facts which militate against this or that comfortable hypothesis; we are assuredly doing our best to deserve the same character."[33] That also is puzzling. Science sets out in life with assuming, by a "great act of faith," that Nature is uniform. She is well aware that the evidence for this assumption is inadequate, that no amount of experience could prove it; but, if she is to start at all, she must make the assumption, so she proceeds to act as though it were proved, as though she knew what she does not know. These are facts; and we take it for granted that no one will wilfully shut his eyes and his ears to them, even if he has some comfortable hypothesis against which they seem to militate.
Again, belief in science is based not on any ground of reason, but upon "the great act of faith" which leads the man of science to assent to it. It is therefore again puzzling to learn that "assent without rational ground for belief is to the man of science merely an immoral pretence," and that "scepticism is the highest of duties; blind faith the one unpardonable sin."[34]
But the reader has probably already correctly divined the solution of these puzzles: the passages quoted above are not intended to apply to science. The blind faith which is illogical, immoral, a pretence and a lie, is, of course, not faith in science, but some other kind, which may therefore be dismissed; and we may start once again with the happy feeling that there is one kind of faith at least which is logical, moral, and real and true.
It is, then, quite honest and logical to have faith sometimes; and, without evidence, to believe some things, e.g. the Uniformity of Nature. Here, however, some readers may interpose with the objection that the man of science has not proved that his faith is logical and moral, and real and true—he has simply assumed it. Quite true; but that is his faith and we must respect it, as we respect any man who holds fast to what he honestly believes to be the real truth. We do not imagine he could believe it if he thought it a pretence or a lie. And we do not call upon him to prove it before we believe him—still less to prove it before he believes it himself.
It is, therefore, we repeat, quite reasonable to believe in the Uniformity of Nature without evidence. The reluctance that is genuinely felt by many minds to take up this position is probably due to a feeling that if we may believe in one thing without evidence, then anyone may believe in anything he likes. And it would not be quite fair to make the rejoinder, What does that matter to you, as long as you are free to believe what you think right? The tendency to dogmatise, and to be intolerant of opinions not our own, is, indeed, strong enough in all of us to make us stand somewhat in dismay of a line of argument which seems to indicate not merely that other people have a right to differ from our opinions, but may quite conceivably be right in so differing. Still, this tendency does not wholly account for our reluctance. That reluctance has, in part at least, a nobler origin than narrow-mindedness and the ignorance which knows not that it is ignorance. It does matter to us what our fellow-men believe. Still more does it matter how and why they choose their beliefs.
The reluctance to admit that it is permissible to believe without evidence even in a truth so undisputed as the Uniformity of Nature, is also in part due to yet another cause. It is felt that to admit belief without regard to evidence is to invite intellectual anarchy, and to leave mankind the helpless prey of ignorance, error, and superstition. Hence, in many candid souls, a lamentable feeling of distraction and hopelessness: to abandon their old faith, even if it has no evidence, is almost more than they can bear; to retain it, knowing that it has no evidence, is to open the floodgates of a saturnalia of unreason by which the foundations of civilisation would be swept away. Hence, too, the zeal with which other minds call for the destruction of every belief, but especially religious belief, not based on evidence, and with which they denounce faith as the one unpardonable sin.
But the error into which both classes of mind fall is a simple one. It consists in imagining that if we take one thing on faith, because there is no evidence, therefore we may believe anything, even if the evidence is conclusive against it—that if we once accept faith, we must for ever abjure reason. The error has been clearly exposed by Professor Huxley, who, after pointing out that reason—ratiocination—is based on faith, says, "But it is surely plain that faith is not necessarily entitled to dispense with ratiocination because ratiocination cannot dispense with faith as a starting-point; and that because we are often obliged, by the pressure of events, to act on very bad evidence, it does not follow that it is proper to act on such evidence when the pressure is absent."[35]
It seems, then, a piece of alarmist exaggeration to say that if we admit one thing, e.g. the Uniformity of Nature, without evidence, we forfeit the right ever again to ask for evidence for any other statement: on the contrary, whenever evidence can be got, we must get it and abide by it. But this only shows that no disastrous consequences will necessarily ensue, if we frankly admit what in any case is the fact, viz. that there is no evidence for the postulate on which all science is built. You will not have committed high treason against the best interests of mankind by acting, in this case, on the principle that a man may sometimes believe a thing on evidence which, he is well aware, is insufficient, or on no evidence at all. On the other hand, in another case, to act on the principle might be, if not high treason, at least mischievous.
It seems, then, first, that there are some things which a man may believe without evidence, and some which he may not; and, next, that he may not believe things the consequences of which would be disastrous or mischievous. But now what of the things not mischievous or disastrous? On what principle are we to choose amongst them? Let us once more follow our guide, the man of science, and ask him on what principle he elected to believe that Nature was uniform, rather than that she was not. I imagine it was once more on the ground of the consequences: grant that Nature is uniform, and then all the marvellous discoveries, the revelations of the past and prophecies of the future, which science has made, become things that we can reasonably believe in. Refuse to believe, withhold your faith, and then you have no reason to believe anything whatever, thought and action alike are paralysed. It is between these consequences that we have to choose. Our choice is an act of will; and it is on our will that our beliefs and our actions depend.
In science, then, we are offered the alternatives: either believe without evidence that Nature is uniform, or renounce all that science has to give. We want to be scientific, so we choose the former. We believe (in science) because we want to believe, not because we have any evidence. To say that we may yield to the impulse to have faith, without being unscientific, is to understate the case: we cannot be scientific without faith.