[PatrickHenry]

I'm not sure that's a true counter-example. As you correctly pointed out, each causal sequence is correctly ordered, within its own frame of reference. It has a "furure-ward" time direction (from cause to consequence). The information about one such causal event travels to the other frame where it's observed; and vice versa. Neither event is a cause of the other. Although an observer may see the distant events "later" than he sees the events in his own frame, or perhaps they may appear to be simultaneous, this isn't a reversal of cause and effect. The observer he still sees the distant events in their proper sequence because he will see the distant cause precede the distant consequence. Perhaps I missed your point.

[longshadow]

Perhaps I missed your point.

Physicist's point (I think) is that not all temporally well-ordered events are causally connected, though surely all causally connected events will be temporally well-ordered.

This implies that the set of causally connected events is a subset of the set of all temporally well-ordered events.

I hope that's clear.... because there'll be a quiz next period!