‘What was at issue here is perhaps easier for us to recognise now than it was for Gifford and his contemporaries. They had indeed learned both from the philosophical influence of the successors of Reid and Stewart and from the heirs of Kant, especially through the teaching of Sir William Hamilton, that what is given to perception and observation is always already informed by concepts and judgements. They did not believe in what Sellars has called the myth of “the given.” But it was part of what I am calling their unitary conception of rationality and of the rational mind that they took it for granted not only that all rational persons conceptualise data in one and the same way that therefore any attentive and honest observer, unblinded and undistracted by the prejudices of prior commitment to belief, would report the same data, the same facts, but also that it is the data thus reported and characterised which provide enquiry with its subject matter.
We by contrast have learned from Gaston Bachelard, Thomas Kuhn, and others that, relative to any particular type of enquiry, there are always two modes of conceptualising and characterising the data which constitute its subject matter, a pretheoretical (although not of course preconceptual) prior-to-enquiry mode and a mode internal to that particular type of enquiry which already presupposes one particular theoretical or doctrinal stance and commitment rather than another. So, to use Kuhn’s example, where those innocent of enquiry see and report a stone swinging from a line, a theoretically committed Aristotelian will observe an instance of constrained natural motion, an adherent of Galileo a pendulum. The criteria for the identity of everyday objects and persons are indeed pretheoretical, so that we are able to assert that it is one and the same swinging stone which is observed by both Aristotelian and Galilean physicists. But there is no way of identifying, characterising, or classifying that particular datum in a way relevant to the purposes of theoretical enquiry except in terms of some prior theoretical or doctrinal commitment (see Thomas S. Kuhn The Structure of Scientific Revolutions, second edition, Chicago, 1971, chapter X).’
p. 16-7. – Three Rival Versions Of Moral Enquiry, Alasdair MacIntyre, 1990.