Mason Gaffney is being misleading when he quotes Locke's: 

"It is ambition enough to be employed as an under-labourer in .
removing some of the rubbish that lies in the way to knowledge, which
certainly had been much more advanced in the world if the endeavors of
ingenious and industrious men had not been much cumbered with the learned
but frivolous use of uncouth, affected, or unintelligible terms . . Vague
and insignificant forms of speech, and abuse of language, have so long
passed for mysteries of science . that it will not be easy to persuade
either those who speak or those who hear them that they are but the covers
of ignorance, and hindrance of true knowledge."  

As Gaffney notes this is from the Essay Concerning Human Understanding. 
Gaffney suggests that Locke is attacking "scientism." While I think there is 
a hint of anachronism in Gaffney's use of 'scientism,' it is worth quoting 
the start of the sentence to Locke's passage (ommitted by Gaffney):

"The commonwealth of learning is not at this time without master-builders, whose mighty designs, in advancing the sciences,
 will leave lasting monuments to the admiration of posterity: but every one must not hope to be a Boyle or a Sydenham; 
and in an age that produces such masters as the great Huygenius and the incomparable Mr. Newton, with some others of that strain, 
it is ambition enough to be employed as an under-labourer in clearing the ground a little..." 

(For those who wish to check: the passage is from the "The Epistle to the 
Reader.") 

In the passage, Locke is making a three-way distinction between:
a) the master-builders (some natural philosophers); b) the under-labourers 
(i.e., Lockean philosophers); c) those that speak uncouth (affected, etc) 
terms (presumably the Scholastics and maybe the Cartesians, too). Regardless 
of how we are supposed to distinguish between Locke's enterprise and that of 
the Master-builders (and I would be the first to admit that Locke's stance 
toward the activities of Huygens and Newton is more ambiguous than this 
passage suggests), I find it hard to see how we are supposed to infer Locke's 
criticism of 'scientism' from this passage.

Eric Schliesser