 This echoes Newton’s second rule of  reasoning,[5]  especially in its generalizing tendency, which Newton explicitly asserts in his third  rule.[6]  That is to say, in his fourth rule, Hume makes explicit what is implied by the simplicity of nature assumption in Newton’s first  rule:[7]  that the same cause always produces the same effect. Also, Hume’s fifth rule is an articulation of Newton’s first and third rules. Hume’s sixth rule is itself an extension of Hume’s fifth.