It is difficult not to notice a curious unrest in the philosophic atmosphere of the time, ... Life is confused and superabundant, and what the younger generation appears to crave is more of the temperament of life in its philosophy, even though it were at some cost of logical rigor and of formal purity. Transcendental idealism is inclining to let the world wag incomprehensibly, in spite of its Absolute Subject and his unity of purpose. Berkeleyan idealism is abandoning the principle of parsimony and dabbling in panpsychic speculations. Empiricism flirts with teleology; and, strangest of all, natural realism, so long decently buried, raises its head above the turf, and finds glad hands outstretched from the most unlikely quarters to help it to its feet again.(William James 1904)
In 1904 William James, the famous American philosopher and psychologist described his philosophy as "Radical Empiricism". Radical Empiricism holds that our minds are identical with our experience. They are nothing more and nothing less than this experience. James uses this identification of mind with experience to abolish the "subject-object" paradox:
"The first great pitfall from which such a radical standing by experience will save us is an artificial conception of the relations between knower and known. Throughout the history of philosophy the subject and its object have been treated as absolutely discontinuous entities; and thereupon the presence of the latter to the former, or the 'apprehension' by the former of the latter, has assumed a paradoxical character which all sorts of theories had to be invented to overcome." James (1904).
If our minds are our experience itself then there is no need for this experience to further perceive this experience. So far so good, but how can a mind perceive if there is not some notion of change where an object of perception becomes analysed? James tries to explain this by saying that "every later moment continues and corroborates an earlier one." Unfortunately in any of these theoretical, instantaneous moments perception is frozen so at any moment the subject would know nothing.
James' analysis is strange because in his "The Principles of Psychology" he writes that we experience whole durations of time and remarks that:
"First of all, we note a marked difference between the elementary sensations of duration and those of space. The former have a much narrower range; the time-sense may be called a myopic organ, in comparison with the eye, for example. The eye sees rods, acres, even miles, at a single glance, and these totals it can afterward subdivide into an almost infinite number of distinctly identified parts. The units of duration, on the other hand, which the time-sense is able to take in at a single stroke, are groups of a few seconds, and within these units very few subdivisions -- perhaps forty at most, as we shall presently see -- can be clearly discerned."
Perhaps when James talks of a moment he really means a short duration in experience taken in at "a single stroke". If this is the case then perception would not be a succession of frozen instants of no duration but whole sequences and actions. This is more like our experience.
If James' "Radical Empiricism" embraces durations, if his observer is extended in time, then Radical Empiricism is very similar to New Empiricism. Sadly it is difficult to find a clear exposition to this effect in James' statement of Radical Empiricism.
It is also extremely difficult to tease out James' ideas on "Natural Realism" and the location of the space of experience. In contrast with James' apparent natural realism, New Empiricism uses the existence of illusions, dreams, and modern fMRI studies to analyse experience as representational rather than Natural Realist.
In summary, the empirical content of Radical and New Empiricism is very similar but the analysis differs, modern data suggesting a representational rather than Natural Realist interpretation.
Field, R.W. (1983).William James and the Epochal Theory of Time
Process Studies, pp. 260-274, Vol. 13, Number 4, Winter, 1983
(Whitehead got it right, dimensional time and 'change' are two different things)
William James (1890). The Principles of Psychology. http://psychclassics.yorku.ca/James/Principles/prin15.htm
William James (1904). A World of Pure Experience. First published in Journal of Philosophy, Psychology, and Scientific Methods, 1, 533-543, 561-570. http://psychclassics.yorku.ca/James/experience.htm