Survivalism and Self-Sufficiency are linked sharing the common aim of self reliance: the first as a planned reaction to a sudden emergency, the second as an organised change of lifestyle.
The Survivalist can be compared to a hunter-gatherer, someone with the forethought to have planned and prepared for famine and change, possibly for a limited time.
It is tempting to believe that the desire for a more independent life-style causes the Survivalist to search for the rationale rather than the reverse.
The Self-Sufficiency enthusiast is for the longer term; preparing and providing for a self-sustainable life encompassing emergency planning as a natural part of the system.
But in some ways, the motivations behind Survivalism seem more educated and realistic, more public spirited and courageous than the milder rationale that encourages the drift to Self-Sufficiency.
There is no doubt that Empires, States and Societies do struggle and sometimes collapse suddenly and violently, either from external attack or from tensions within.
Against the background of human history, political and religious disputes are far more likely to cause chaos than the forces of nature - at least on the national scale.
To suggest that man is usually nastier than nature does not seem to be an extreme philosophy, even if the expression of any perceived danger can be bigoted and unpleasant.
The provision of a safe milk supply came home forcibly some years ago to the writer.
Chernobyl happened, far far away in the remote USSR, but very quickly in today's well connected world we knew that it was a major disaster likely to contaminate the land over a wide area.
The East of England was very unlikely to be troubled at such a vast distance - and against the prevailing westerly wind.
Nevertheless, as a precaution we kept the goats in their stables for a few days.
It later transpired that our care was unnecessary. As we expected, we were not contaminated by radioactive fall-out.
But our caution was well founded, a massive weather system took a swirl of air from far away Chernobyl, sluiced it around Scandinavia, before allowing rain to dump some fall-out to the west of us, over a small part of the Welsh mountains. They still have contamination in this area - and tests - with restrictions that are still in force.
So, it is not just having the skill to milk the goat, but actually having a goat to milk, housing, information about an imminent threat and the resources and wit to take appropriate action.