A second advantage of the syllogism is, that it makes us fully aware of what an inference implies.  An inference must have some grounds, or else it is a mere prejudice; but whatever the grounds, if sufficient in a particular case, they must be sufficient for all similar cases, they must admit of being generalised; and to generalise the grounds of the inference, is nothing else than to state the major premise.  If the evidence is sufficient to justify the argument that camels are herbivorous because they are ruminants, it must also justify the major premise, All ruminants are herbivorous; for else the inference cannot really depend merely upon the fact of ruminating.  To state our evidence syllogistically, then, must be possible, if the evidence is mediate and of a logical kind; and to state it in this formal way, as depending on the truth of a general principle (the major premise), increases our sense of responsibility for the inference that is thus seen to imply so much; and if any negative instances lie within our knowledge, we are the more likely to remember them.  The use of syllogisms therefore tends to strengthen our reasonings.

A third advantage is, that to formulate an accurate generalisation may be useful to others:  it is indeed part of the systematic procedure of science.  The memoranda of our major premises, or reasons for believing anything, may be referred to by others, and either confirmed or refuted.  When such a memorandum is used for further inferences, these inferences are said, in the language of Formal Logic, to be drawn from it, as if the conclusion were contained in our knowledge of the major premise; but, considering the limited extent of the material evidence, it is better to say that the inference is drawn according to the memorandum or major premise, since the grounds of the major premise and of the conclusion are in fact the same (Mill:  Logic, B. II. c. 3).  Inductive proofs may be stated in Syllogisms, and inductive inferences are drawn according to the Law of Causation.

Sec. 7.  To assume that resemblance is a ground of inference, and that substance and attribute, or cause and effect, are phenomena constantly related, implies belief in the Uniformity of Nature.  The Uniformity of Nature cannot be defined, and is therefore liable to be misunderstood.  In many ways Nature seems not to be uniform:  there is great variety in the sizes, shapes, colours and all other properties of things:  bodies falling in the open air—­pebbles, slates, feathers—­descend in different lines and at different rates; the wind and weather are proverbially uncertain; the course of trade or of politics, is full of surprises.  Yet common maxims, even when absurd, testify to a popular belief that the relations of things are constant:  the doctrine of St. Swithin and the rhyme beginning ‘Evening red and morning grey,’ show that the weather is held to be not wholly unpredictable; as to human affairs, it is said