[Alamo-Girl]

Thank you for keeping me in the loop on this sidebar!

We can never know how things really are – and that is (paradoxically) the only certainty we do know.

Precisely so. That is part of the "observer problem."

On the "if/then"s - I strongly agree with betty boop that they are causal per se, i.e. cause/effect.

Complementarities are more akin to the two sides of a coin. It's not a coin without both sides.

However, if it comes up "heads" when tossed, you might win something in which case the observed event is causal though heads/tails remain complementary.

[kosta50]

However, if it comes up "heads" when tossed, you might win something in which case the observed event is causal though heads/tails remain complementary

No, they are actually mutually exclusive (either-or). One wins, the other one loses. They eliminate each other.

If-then is conditionally complementary. They re-informce each other.

[betty boop]

Complementarities are more akin to the two sides of a coin. It's not a coin without both sides.

However, if it comes up "heads" when tossed, you might win something in which case the observed event is causal though heads/tails remain complementary.

Beautifully, cogently well-explained, Alamo-Girl!