(18) “The uniformities we expect to find in the world take two main aspects, one of which is indicated by the term _thing_ and the other by the term _circumstance_.” Aikin’s Principles of Logic, 1905; p. 233. In the light of the two fundamental laws of universal causation and uniformity of nature explain and illustrate the quotation. (19) Explain the principle of teleology as related to analogy. Hibben, 1908; p. 317. CHAPTER 18. THE FIVE SPECIAL METHODS OF OBSERVATION AND EXPERIMENT.[13] =1. THE AIM OF THE FIVE METHODS.= The primary forms of induction have been divided into _simple enumeration_, _analogy_ and _analysis_ . Conditioning these forms are the two laws, _uniformity of nature_ and _universal causation_. Since these laws are always concerned with causes, we may refer to them as together expressing the fundamental “_fact of causation_.” Wherever there is a causal connection, no matter how slight, these laws obtain. Though “the fact of causation” probably conditions all forms of induction, it is most conspicuous in the third form; namely, Analysis. Here the main aim is to establish a causal connection of some kind; an aim which may be accomplished through the medium of observation and experiment. Incident to this notion, John Stewart Mill formulated five experimental methods of induction. These are known according to the following distinctive titles: 1. The Method of Agreement. 2. The Method of Difference. 3. The Joint Method of Agreement and Difference. 4. The Method of Concomitant Variations. 5. The Method of Residues. =2. METHOD OF AGREEMENT.= (1) Principle stated. As stated by Mill the principle of the Method of Agreement is this: “If two or more instances of the phenomenon under investigation have only one circumstance in common, the circumstances in which alone all the instances agree is the cause (or effect) of the given phenomenon.” This notion is given in clearer terms by Jevons and Creighton. Viz.: “_The sole invariable antecedent of a phenomenon is probably its cause_”; and “_The sole invariable consequent of a phenomenon is probably its effect_.” It is known that an antecedent is anything which _precedes_; while a consequent is anything which _follows_. To be regarded as a cause, an antecedent must be _invariable_, and to be regarded as an effect, a consequent must likewise be _invariable_. Antecedents and consequents which are in no way constant could hardly have any causal connection. (2) Method symbolized. Let P₁, P₂, P₃, P₄, etc., represent the phenomenon as it may appear the first, second, third, fourth, etc., times, and let A, B, C, etc., stand for the various antecedents, or the various consequents as the case may demand. These two forms may now be used to illustrate the two statements which summarize Agreement: First statement.