In the Vienna of the late 1020s and 1930s there throve an internationally famous philosophical bunch called the logical positivists.... They said that a key ingredient of knowledge was "sense data," and proclaimed emphatically, in the words of... J. S. L. Gilmour, that sense data are "objective and unalterable." …Good guess, but no cigar!

Ch.7 A Trip Through the Perception Factory - Global Brain: The Evolution of Mass Mind from the Big Bang to the 21st Century (2000)