Terry: Some actions considered to be bad by our society have favorable consequences.
Terry and Pat's Conclusion
Some bad actions are actually good.
Terry's Evidence
An action is good only if it has favorable consequences. ( good action → favorable consequences )
Some bad actions have favorable consequences.
Pat's Evidence
No actions considered bad have favorable consequences. ( bad action → ~favorable consequences )
Some good actions don't have favorable consequences.
Evaluate
You gotta love how erudite these two sound (), while totally botching conditional logic. It's also funny that Terry and Pat are two of the most androgynous names, so I'll randomly assign Terry a male pronoun and Pat a female one.
Whenever we're doing Flaw and see conditional logic trigger words (only if, no), then we should immediately suspect a Necessary vs. Sufficient illegal move, where the author does an illegal reversal or negation to get to their conclusion.
Terry is picturing these two ideas, some actions considered bad have favor conseq. favor conseq. → good and that's how he arrives at some actions considered bad are good
But of course we don't have a conditional that says "if favorable consequences, then good", we have the reverse of that.
Similarly, Pat is picturing these two ideas,
some good actions are not favor conseq. not favor conseq. → considered bad and that's how she arrives at some good actions are considered bad
But of course she didn't say that "if not favorable consequences, then considered bad", she said the reverse of that.
Goal
Since both authors are doing illegal reversals of the conditionals they provided, they are both confusing a Necessary condition with a Sufficient one.