THREE:However, as we have seen, he is not above turning it against Mill. The drift of his own illustration is not very clear, but we suppose it implies that the matron unconsciously frames the general proposition: My remedy is good for all children suffering from the same disease as Lucy; and with equal unconsciousness reasons down from this to the case of her neighbours child. Now, it is quite unjustifiable to call Mills analysis superficial because it leaves out of account a hypothesis incompatible with the nominalism which Mill professed. It is still more unjustifiable to quote against it390 the authority of a philosopher who perfectly agreed with those who disbelieve in the possibility of unconscious knowledge,286 and contemptuously rejected Platos opinion to the contrary. Nor is this all. The doctrine that reasoning is from particulars to particulars, even when it passes through general propositions, may be rigorously deduced from Aristotles own admissions. If nothing exists but particulars, and if knowledge is of what exists, then all knowledge is of particulars. Therefore, if the propositions entering into a chain of reasoning are knowledge, they must deal with particulars exclusively. And, quite apart from the later developments of Aristotles philosophy, we have his express assertion, that all generals are derived from particulars, which is absolutely incompatible with the alleged fact, that all knowledge, all thought, rests on universal truths, on general propositions; that all knowledge, whether deductive or inductive, is arrived at by the aid, the indispensable aid, of general propositions. To Aristotle the basis of knowledge was not truths of any kind, but concepts; and in the last chapter of the Posterior Analytics he has explained how these concepts are derived from sense-perceptions without the aid of any propositions whatever.Writers on mechanical subjects, as a rule, have only theoretical knowledge, and consequently seldom deal with workshop processes. Practical engineers who have passed through a successful experience and gained that knowledge which is most difficult for apprentices to acquire, have generally neither inclination nor incentives to write books. The changes in manipulation are so frequent, and the operations so diversified, that practical men have a dread of the criticisms which such changes and the differences of opinion may bring forth; to this may be added, that to become a practical mechanical engineer consumes too great a share of one's life to leave time for other qualifications required in preparing books. For these reasons "manipulation" has been neglected, and for the same reasons must be imperfectly treated here. The purpose is not so much to instruct in shop processes as to point out how they can be best learned, the reader for the most part exercising his own judgment and reasoning powers. It will be attempted to point out how each simple operation is governed by some general principle, and how from such operations, by tracing out the principle which lies at the bottom, it is possible to deduce logical conclusions as to what is right or wrong, expedient or inexpedient. In this way, it is thought, can [6] be established a closer connection between theory and practice, and a learner be brought to realise that he has only his reasoning powers to rely on; that formul?, rules, tables, and even books, are only aids to this reasoning power, which alone can master and combine the symbol and the substance.
