_Logical Synthesis_ is the exact opposite of Logical Analysis. In the latter we strive to separate and take apart; in the former we strive to bind together and combine the particulars into the general. Beginning with individual things and comparing them with each other according to observed points of resemblance, we proceed to group them into species or narrow classes. These classes, or species, we then combine with similar ones, into a larger class or genus; and then, according to the same process, into broader classes as we have shown in the first part of this chapter.
The process of Synthesis is calculated to develop and cultivate the mind in several directions and exercises along these lines will give a new habit and sense of orderly arrangement, which will be most useful to the student in his every-day life. Halleck says: “Whenever a person is comparing a specimen to see whether it may be put in the same class with other specimens, he is _thinking_. Comparison is an absolutely essential factor of thought, and classification demands comparison. The man who has not properly classified the myriad individual objects with which he has to deal, must advance like a cripple. He, only, can travel with seven-league boots, who has thought out the relations existing between these stray individuals and put them into their proper classes. In a minute a business man may put his hand on any one of ten thousand letters if they are properly classified. In the same way, the student of history, sociology or any other branch, can, if he studies the subjects aright, have all his knowledge classified and speedily available for use…. In this way, we may make our knowledge of the world more minutely exact. We cannot classify without seeing things under a new aspect.”
The study of Natural History, in any or all of its branches, will do much to cultivate the power of Classification. But one may practice classification with the objects around him in his every-day life. Arranging things mentally, into small classes, and these into larger, one will soon be able to form a logical connection between particular ideas and general ideas; particular objects and general classes. The practice of classification gives to the mind a constructive turn–a “building-up” tendency, which is most desirable in these days of construction and development. Regarding some of the pitfalls of classification, Jevons says:
“In classifying things, we must take great care not to be misled by outward resemblances. Things may seem to be very much like each other which are not so. Whales, porpoises, seals and several other animals live in the sea exactly like fish; they have a similar shape and are usually classed among fish. People are said to go whale-fishing. Yet these animals are not really fish at all, but are much more like dogs and horses and other quadrupeds than they are like fish. They cannot live entirely under water and breathe the air contained in the water like fish, but they have to come up to the surface at intervals to take breath. Similarly, we must not class bats with birds because they fly about, although they have what would be called wings; these wings are not like those of birds and in truth bats are much more like rats and mice than they are like birds. Botanists used at one time to classify plants according to their size, as trees, shrubs or herbs, but we now know that a great tree is often more similar in its character to a tiny herb than it is to other great trees. A daisy has little resemblance to a great Scotch thistle; yet the botanist regards them as very similar. The lofty growing bamboo is a kind of grass, and the sugarcane also belongs to the same class with wheat and oats.”
Remember that analysis of a genus into its component species is accomplished by a separation according to _differences_; and species are built up by synthesis into a genus because of _resemblances_. The same is true regarding individual and species, building up in accordance to points of resemblance, while analysis or separation is according to points of difference.
The use of a good dictionary will be advantageous to the student in developing the power of Generalization or Conception. Starting with a species, he may build up to higher and still higher classes by consulting the dictionary; likewise, starting with a large class, he may work down to the several species composing it. An encyclopedia, of course, is still better for the purpose in many cases. Remember that Generalization is a prime requisite for clear, logical thinking. Moreover, it is a great developer of Thought.