CO-EXISTENCES INDEPENDENT OF CAUSATION. 415 



portion only. We can not conclude (wlicre causation is not concerned), 

 because a proposition is true of a number of things resembling one another 

 only in being animals, that it is therefore true of all animals. If, indeed, 

 any thing be true of species which differ more from one another than either 

 differs from a third, especially if that third species occupies in most of its 

 known properties a position between the two former, there is some proba- 

 bility that the same thing will also be true of that intermediate species ; for 

 it is often, though by no means universally, found, that there is a sort of 

 parallelism in the properties of different Kinds, and that their degree of 

 unlikeness in one respect bears some proportion to their unlikeness in oth- 

 ers. We see this parallelism in the properties of the different metals; in 

 those of sulphur, phosphorus, and carbon ; of chlorine, iodine, and bromine ; 

 in the natural orders of plants and animals, etc. But there are innumera- 

 ble anomalies and exceptions to this sort of conformity ; if indeed the con- 

 formity itself be any thing but an anomaly and an exception in nature. 



Universal propositions, therefore, respecting the properties of superior 

 Kinds, unless grounded on proved or presumed connection by causation, 

 ought not to be hazarded except after separately examining every known 

 sub-kind included in the larger Kind. And even then such generalizations 

 must be held in readiness to be given up on the occurrence of some new 

 anomaly, which, when the uniformity is not derived from causation, can 

 never, even in the case of the most general of these empirical laws, be con- 

 sidered very improbable. Thus, all the universal pi'opositions which it has 

 been attempted to lay down respecting simple substances, or concerning 

 any of the classes which have been formed among simple substances (and 

 the attempt has been often made), have, with the progress of experience, 

 either faded into inanity, or been proved to be erroneous ; and each Kind 

 of simple substance remains, with its own collection of properties apart 

 from the rest, saving a certain parallelism with a few other Kinds, the most 

 similar to itself. In organized beings, indeed, there are abundance of 

 propositions ascertained to be universally true of superior genera, to many 

 of which the discovery hereafter of any exceptions must be regarded as 

 extremely improbable. But these, as already observed, are, we have every 

 reason to believe, properties dependent on causation.* 



* Professor Bain (Logic, ii., 13) mentions two empirical laws, which he considers to be, with 

 the exception of the law connecting Gravity with Kesislance to motion, " the two most wide- 

 ly operating laws as yet discovered whereby two distinct properties are conjoined throughout 

 substances generally." The first is, "a law connecting Atomic Weight and Specific Heat by 

 an inverse proportion. For equal weights of tlie simple bodies, the atomic weight multiplied 

 by a number expressing the specific heat, gives a nearly uniform product. The products, for 

 all the elements, are near the constant number 6." The other is a law which obtains "be- 

 tween the specific gravity of substances in the gaseous state, and the atomic weights. The 

 relationship of the two numbers is in some instances equality ; in other instances the one is a 

 multiple of the other." 



Neither of these generalizations has the smallest appearance of being an ultimate law. 

 They point unmistakably to higher laws. Since the heat necessary to raise to a given tem- 

 perature the same weight of different substances (called their specific heat) is inversely as 

 their atomic weight, that is, directly as the number of atoms in a given weight of the sub- 

 stance, it follows that a single atom of every substance requires the same amount of heat to 

 raise it to a given temperature ; a most interesting and important law, but a law of causation. 

 The other law mentioned by Mr. Bain points to the conclusion, that in the gaseous state all 

 substances contain, in the same space, the same number of atoms ; which, as the gaseous 

 state suspends all cohesive force, might naturally be expected, though it could not have been 

 positively assumed. This law may also be a result of the mode of action of causes, namely, 

 of molecular motions. The cases in which one of the numbers is not identical with the oth- 

 er, but a multiple of it, may be explained on the nowise unlikely supposition, that in our pres- 

 ent estimate of the atomic weights of some substances, we mistake two, or three, atoms for 

 one, or one for several. 



