Shepherd in the discussion prior to this passage has noted some passages in Locke that are parallel to some passages in Hume; in the process of arguing that Locke means something in these passages very different from what Hume means, she presents the following summary of the psychological process of causal reasoning.
To return to Mr. Locke, he merely meant to say, that nature in her regular and usual modes of operation, from Cause and Effect might form
irregular collections of qualities, not to be detected by mere appearances; and therefore unworthy
on that account only, of retaining the
names of regular species, which are
also named on account of their
tried Effects and properties. But every man acquainted with Mr. Locke's writings must consider him, as far from wishing to authorize in future times such a scheme as that of Mr. Hume's. Nor do I think he would dissent from my notions, that the method the mind takes to judge of the kind of objects which are present is:
1stly.--By tracing the
manner of their formation.
2dly.--By considering an invariable regularity in nature as reasonable to be depended upon, being itself an invariable effect from an equal Cause.
3dly.--By the application of various senses to the affections of the particles.
4thly.--By the consideration that the sensible qualities being similar is a presumption in favor of similar secret powers, as
truly similar objects would necessarily
appear the same.
5thly.--That in like manner when
Effects are
apparently similar a presumption is formed in favor of apparently similar causes, having given birth to
like secret powers in the EFFECTS, as well as
their sensible qualities.
6thly.--That the mind quickly and habitually surveys these things; so that the understanding being
accomplished in such latent, and constant reasoning; may uniformly blend and use it, although it may find a difficulty of analyzing it when called for.
7thly.--That after the application of an exact experiment, it is impossible to imagine a difference of qualities to arise under the same circumstances.
It is a strange that a system at once so unstable and confused, as Mr. Hume's, should ever have been built upon any notions of Mr. Locke, whose moral conclusions are so much at variance with his.