What was Justice Potter Stewart referring to when he said, "I know it when I see it"?

Using quasi-experiments to draw causal inferences in field experiments

A) may give us less than high confidence but will still give us more information than not experimenting at all. B) is more costly and more time consuming than answering the same question in the laboratory. C) is based on new statistical procedures. D) All of the above

In the case of an independent candidate, or a candidate representing a minor party, the most serious problem is to convince voters

A) that voting is their patriotic duty. B) of the importance of foreign policy issues. C) of the importance of domestic policy issues. D) to reject the major-party candidates. E) that pluralism is fundamentally flawed.