First Principles

Midgley suggests that there is a feedback loop between our deep assumptions and their surface level manifestations. Messages move from the depths to the surface, and back again.

So whilst deep assumptions are likely conditioned by biological factors (i.e. certain types are more prone to certain beliefs) they are also affected by practical experience. This is essentially the nature/nurture, genotype/phenotype split. 

Value-judgements about importance determine, among other things, what limits we set to the self itself, how far we think it extends and how sharply we separate it from what is around it.

A self is not a given distinct object like a ball or a stone. For instance, the extreme individualistic model of selfhood - the social atomism which underlies social contract thinking - treats each self as independent, an object like a billiard-ball radically cut off from its fellows. But it does not do this on factual grounds. It is not a scientific discovery that selves are in fact shaped like billiard-balls.

It arises chiefly out of moral indignation at the oppression which has often resulted from a more organic, connected, hierarchical view of social relations. Social atomism flows from deciding that the bad consequences of hierarchical systems are so important that the conceptual scheme underlying them must be ditched and replaced by a more separatist one.

These general ways of conceiving the world obviously make an enormous difference, not just to our notions about how we ought to act but also to our views about which facts we ought to attend to and what methods we should use in thinking about them.

By affecting our selection of topics they alter our factual view of the world as well as our moral view about how we must deal with it.

[Mary Midgley]
Science and Poetry, p. 204-5