[3]Berkeley's argument is an attempt to show that materialism or a mind-independent world is logically impossible.
[4] Bertrand Russell among others believed Berkeley's argument "seems to depend for its plausibility upon confusing the thing apprehended with the act of apprehension":[5] "If we say that the things known must be in the mind, we are either un-duly limiting the mind's power of knowing, or we are uttering a mere tautology.
Thus when we realize the nature of knowledge, Berkeley's argument is seen to be wrong in substance as well as in form, and his grounds for supposing that 'idea'—i.e.
[4] Charles Sanders Peirce agreed with Berkeley that "what we think of cannot possibly be of a different nature from thought itself.
[7] Some claim that Berkeley was not making a master argument at all and that what he was actually trying to show was that the substance 'matter' was actually an abstract concept that passed itself off in peoples' minds as an object of immediate experience.