The exclusion from logic of all consideration of the facts on which propositions are founded, is thus endeavoured to be justified by the Archbishop of Dublin:--'No arithmetical skill will secure a correct result, unless the data are correct from which we calculate: nor does any one on that account undervalue arithmetic; and yet the objection against logic rests on no better foundation.' This is true, but is it true that arithmetic is on _this account_ to be imitated? If the arithmetician must take his data for granted, it is what the searcher after truth must never do--_he_ must use his eyes and examine for himself, in all cases, as far as possible, unless he intends to be deceived. And for want of such precaution as this, the arithmetician is at sea the moment he steps out of the narrow path of mechanical routine. Who is not aware of the failures of calculation when applied to the general business of life--to statistics, moral and political? Every day, facts have to be called in to correct the egregious blunders of figures.* The calculations are conducted in most approved form, but are of no use. Does not this demonstrate that when arithmetic, like logic, is applied to the business of life, general rules for securing the accuracy of data would be of essential service? Supposing, however, that arithmetic could do very well without them, does it follow that logic should, when it would be safer and more efficient with them? * 'In Art, in Practice, innumerable critics will demonstrate that most things are impossible. It was proved by fluxionary calculus, that steam-ships could never get across from the farthest point of Ireland to the nearest of Newfoundland; impelling force, resisting force, maximum here, minimum there; by law of Nature, and geometric demonstration--what could be done? The Great Western could weigh anchor from Bristol Port; that could be done. The Great Western, bounding safe through the gullets of the Hudson, threw her cable out on the capstan of New York, and left our still moist paper-demonstration to dry itself at leisure.'-- Thomas Carlyle, Chartism, pp. 96-7. Since our author's canons are held absolute in the schools, it may be useful to consider this last cited argument in another light. A stronger objection may be urged, one which particularly addresses itself to those who mistake mere pertinence for general relevance, and suppose that a single analogy decides a case. His Grace reasons, that, because arithmetic does not concern itself about its data, logic should follow the same example. But why overlooks he pure mathematics--a much higher science than arithmetic? Surely geometry, which through all time has been the model of the sciences, was better worthy than arithmetic to be the model of logic! Was it classical in the principal of St. Alban's College to abandon Euclid and cleave unto Cocker or Walkingame?