error in the observer, a law of nature is established; and so long as this law is received as such, the assertion that on any particular occasion the cause A took place and yet the effect B did not follow, _without any counteracting cause_, must be disbelieved. In fact, as he winds up this part of the argument by saying: "We cannot admit a proposition as a law of nature, and yet believe a fact in real contradiction to it. We must disbelieve the alleged fact, or believe that we were mistaken in admitting the supposed law."(1) Mr. Mill points out, however, that, in order that any alleged fact should be contradictory to a law of causation, the allegation must be not simply that the cause existed without being followed by the effect, but that this happened in the absence of any adequate counteracting cause. "Now, in the case of an alleged miracle, the assertion is the exact opposite of this. It is, that the effect was defeated, not in the absence, but in consequence of a counteracting cause, namely, a direct interposition of an act of the will of some being who has power over nature; and in particular of a Being, whose will being assumed to have endowed all the causes with the powers by which they produce their effects, may well be supposed able to counteract them."(2) A miracle, then, is no contradiction to the law of cause and effect; it is merely a new effect supposed to be introduced by the introduction of a new cause; "of the adequacy of that cause _if present,_(3) there can be no doubt; and the only antecedent improbability which can be ascribed to the miracle is the improbability that any such cause existed." Mr. Mill then continues, resuming his criticism on Hume's argument: {82}