A diet whose protein comes from fish is much healthier than one whose protein comes from red meat.
Opposing Point
A diet whose protein comes from fish is much healthier than one whose protein comes from red meat.
Evidence
If everyone were to adopt this healthier diet, most of the marine species on which it is based would become extinct, making it impossible.
Conclusion
We should not recommend the universal adoption of such a diet.
Evaluate
This argument advocates against making a recommendation that is good for someone on the basis that if everyone followed the advice, it would become untenable.