Let's start with the basic function:

y = f(x);

It formalizes a relationship between "x" (the 'independent' variable) and "y" (the 'dependent' variable).. This relationship is characterized by the "function" "f()". The fundamental principle is that, if we know "x" and we know "f()" then we know, now and for ever, under every conditions, "y". Time will not impact this relationship, nor will using the function in the past have any impact on the our expectations of what is to happen when we use it the next time around. This is the fundamental principle of Newtonian physics: "when kicking a stone ...." It is of such functions that I think when I talk about "causality."

The applicability of this kind of causal relationships to human interaction (and in fact all interaction between life forms) has been challenged repeatedly on similar grounds: every evidence suggests that the occurrence of an interaction between X and Y in conditions F() changes to some extent F(). How it does this is the fundamental question in the social sciences: what is the role of history in interaction?

Let's rewrite the basic function:

repeat until something happens
{y = f(x):
x = x+1;
}

Note that, in such a function, the value of Y would move up in a straight line. In human terms, it would mean that every time something got done, more of it would have to be done the next time around, and so on for ever or until breakdown.

Both for formal reasons, and on the basis of observation of any kind of life processes, the basic function has to be re-written further to include a correction mechanism that prevents the values from moving too far in either directions:

repeat until something happens
{y = f(x+1):
if (x < 10) x = x+1;
else if (x > 0) x = x-1;
}

In this case X will go up to 9, Y will go up to 10, then X will go down to 1, Y will go down to 2, and then the process will repeat itself. This is the basic model for an homoeostatic "system." In this instance the word "system" refers to the parts, the relationships between the parts, and the corrective mechanisms that keep variation within a certain range. (This could also be the formal definition of a "culture" as a man-made, temporary stable, organization of parts, relationships, and corrective mechanisms)

In human life (indeed in all life) something will always happen and the principle of such systems is that, however in self-correcting balance they may be, they are also "fragile" on the cusp of a transformation that may or may not be inscribed in the system itself.