"Every time we observe an IC system an intelligent agency is ALWAYS the cause."
If you take the above as a hypothesis, then it can be refuted
by any feasible sequence that could lead to the IC system
without the intervention of intelligence (in a common understanding
of that term).
If one can imagine ADDING components to an IC system that do not
impair it's primary output, but allow interaction with other
sub-systems to provide secondary outputs, then one cannot
rule out that those additions did not exist in the past,
and were lost.
If the system can then be broken into separate sub-systems
(neither of which perform the final task) then IC can be seen
as illusory at best.
Even in human design (where 'intelligence' is involved) some
designs are a matter of combining existing designs and then
removing some parts that are not required for the project in
hand. The result is IC, the route wasn't atomic.
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