Collingwood's examples of Absolute Presuppositions

We do not acquire absolute presuppositions by arguing; on the contrary, unless we have them already arguing is impossible to us. Nor can we change them by arguing; unless they remained constant all our arguments would fall to pieces. We cannot confirm ourselves in them by ‘proving’ them; it is proof that depends on them, not they on proof (An Essay on Metaphysics 1998: 173).

What is the difference between presuppositions and assumptions? C. Ribeiro states:

Collingwood (1940) made a distinction between presuppositions and assumptions. Presuppositions are non-justified implicit implications. They differ from assumptions because the latter are stated openly, are explicit, not implicit. We assume by an act of free will: ‘To assume is to suppose by an act of free will. A person who ‘makes an assumption’ is making a supposition about which he is aware that he might if he chose make not that but another. (…)’ (Collingwood 1940: 27) Presuppositions, however, work in the darkness. But they establish logical connections with the statements formulated in our explicit thought. 

Hyrkannen () p. 255 observes:

• Presuppositions, especially absolute ones, could thus be defined as tacit assumptions, something humans take, more or less, for granted, or which are normally left unscrutinized, unreflected on, unquestioned, untested or unverified. We might call this dimension of thought the dimension of beliefs.

Louis O. Mink

• absolute presuppositions are ‘widely as well as deeply shared; they are ways in which men may think alike as well as be alike in what they think’
• What men have done can be understood only in terms of what they have thought. What they have thought can be understood only in terms of the questions and problems to which they sought answers. And what their questions and problems were can be understood only in terms of the conceptual systems in whose absence those questions and problems could not even arise and be formulated.

Some examples of AP:

• all events have a cause
• the principle of the continuity of nature in time and space, 
• the existence of God
• the principle that mathematics is applicable to the natural world and hence that natural science is essentially an applied mathematics
• all events happen according to law (EM, 150).
• nature is uniform (Mill's EM, 152)

References

• Ribeiro, C. (2015) http://www.philosophica.ugent.be/fulltexts/90-3.pdf
• Hyrkkänen, M. (2009) All History is, More or Less, Intellectual History: R. G. Collingwood's Contribution to the Theory and Methodology of Intellectual History, Intellectual History Review,19:2, 251 — 263
• Mink, L. Collingwood’s Dialectic of History, History & Theory, 7 (1968), 3–37 (25)