POSSIBLE and IMPOSSIBLE. The first of these words is of little interest, except as the contradictory of the second. The word im possible is used in common life to signify highly improbable, or utterly incredible. In this sense the impossible of yesterday is the possible of to-day. It is also used to signify that which would contradict the laws of nature, by which we always mean our view, knowledge, or experience of the laws of nature. In this sense also the impossible of yesterday is the possible of to-day. It was impossible that a missile should be thrown by the hand, and after traversing the air return to the hand again, until the boomerang of the savage found its way to the knowledge of the physical philosopher.
The true use of the word impossible is that which its etymology demands, that which cannot be. And how can we acquire the idea of that which cannot be, in the universe of an omnipotent Creator. On examination of the question, we arrive at no result but this, that all we can grasp of impossibility is inconceivability, and that every thing is conceivable which does not contradict itself, let it contradict what else it may. And thus (MATHEMATICS, col. 430) we arrive at the conclusion that nothing is impossible except that which contradicts the laws of thought, or the laws of the necessary matter of thought. Impossibility, then, is a word of logic and mathematics, and nothing else. It is impossible that "every x is v" and "some xs are not vs," should both be true : it is impossible that two sides of a triangle should be loss than the third.
But arc we not, under this restriction, converting the impossible into the possibly possible? May there not be notions which though self-con tradictory to our minds, arc not so to minds of another stamp, or of a higher stamp. This question has been discussed before now : it has been asked whether God could nzake two and two to be fire. In order to make this question intelligible, that is, to show that it is beyond intelligible answer, we must assert, without being able to go into full deduction, that every one of our impossibilities is resoluble into the idea of something which at once exists and does not exist. In the two and two which make five, there is an extra unit which is there and is not. 'When Euclid shows an impossibility he does it by showing that the notion requires a whole which is no greater than its part : so that the additional part which makes up the whole exists without existence. That is to say, in compassing an impossibility we start from this enunciation— To be and not to is the question.
Now when we are seriously asked—Is it in the power of the Creator to make the same thing to exist and not to exist at the same moment —we answer that our minds are so constructed that it looks very much as if we were intended to believe that it is not. And there we leave it : we would rather employ ourselves on the old question of the schoohnen,—which God loves best, a possible angel, or an existing fly.
But there is another point of view, from which the question might have been asked, and which perhaps lurked in the minds of those who first asked it. Can the Creator make two and two to be five I The simplest mode of relation, that which we signify by and, gives four. But it is not beyond conceivability that a mind might be so constructed that its simplest operation should be different from ours. It would not cost Mr. Babbage an hour's thought to alter the funda mental structure of his difference-engine in such a manner that, instead of adding the two numbers presented, the machine should, of necessity, throw in an extra unit. That which man can execute, he can conceive the Creator performing on a larger scale : accordingly, it is within possibility that a mind should exist in which the simplest junction, to that mind, of two and gives five, but the mode of junction would not be what we call addition.
The main purpose of such an article as the present is to bring for ward the true meaning, iu our laWs of thought, of the word impossible ; and to help the reader, should he need such help, to avoid importing the true meaning of the word into the phrases, " morally impossible," and " physically impossible." The word here used should be inerezliblc. A confusion of this sort very frequently exists. The mind allows experience to fashion a law of nat'rc, and postulates that the future shall agree with the past, and obey that law. This postulate 011C0 assumed, disobedience is an impossibility, also assumed ; for simul taneous obedience and disobedience would be simultaneous existence and non-existence. But the question whether the law of nature, or what is assumed to bo the law of nature, shall continua without excep tion for ever, cannot be argued upon the assumption that the settlement shall be of one preconcerted kind.
An eminent experimenter has laid down the following as his mode of proceeding : and that he does not intend the words possible and impossible to be used in their vague and popular sense is evident from his repeating the dictum, without remark or explanation, after full warning of what he seemed to be doing. "Before we proceed to con sider any question involving physical principles, we should set out with clear ideas of the naturally possible and impossible." No doubt if there be a naturallypossible and impossible, which is more than our experimenter can know, and if he can get a clear idea of it, which is more than he can do, his plan is a very good one. In the meanwhile, situated as we are in this world, we believe that a remark * made by Arago, a year before the above method was propounded, is much more to the purpose. It is that he who pronounces the word impossible, except in pure mathematics [to which logic ought to be added), shows a lack of prudence.