Short twitter lesson on the connections between Antifragility and Requisite Variety:

Living systems must be able to respond to the variety of their environment in order to survive. 1/9

For instance, if the environmental temperature becomes too cold for physiological processes to proceed, an organism must have means to warm itself, else perish. 2/9

But there is no a priori map of the variety of the environment, no list to reference of all the ways the environment might impinge upon an agent. 3/9

Moreover, there is only so much variety a finite system can produce -- it must select the variety that matches the most relevant environmental stressors. Hence, variety itself must be adaptive. 4/9

Antifragility is the way in which a system detects relevant variety, and then produces variety, and, critically, scales up the most relevant varieties (to the exclusion of other, hopefully irrelevant, varieties). 5/9

This is why, as @nntaleb says, the environment communicates to the system via stressors. Stressors give hints as to what varieties are relevant, and need to be counteracted. 6/9

An antifragile system "overshoots" the scaling of its internal varieties relative to the scale it has experienced to date as an anticipatory action. You haven't yet seen the tallest mountain. 7/9

The underlying assumptions are that (1) a variety is relevant due to the stress it caused during a particular experience and (2) the scale of an experienced variety does not represent the upper bound of the scale the environment might deliver. 8/9

Antifragility is the cybernetics of the cat, not the washing machine. 9/9

(patriotic cat courtesy of @GrantSSC )