forum 7: week of 27 Feb - pragmatic encroachment
Personally, I have only minor qualms about 1 & 3. My problem with the second claim is the condition "if the stakes are high enough". I still don't buy that high-stakes situations should have an effect on "certainty", implying that it also has an effect on knowledge (or else what would that certainty pertain to). I'm inclined to agree with Ange that the entire argument seems to be about pragmatics rather than epistemics.
In support of the Jeremy Fantl and Mathew McGrath paper commitment to pragmatic encroachment, in the absence of certainty in knowledge, I offer the example of Winston Churchill.
In the book titled Troublesome Young Men The Rebels Who Brought Churchill To Power, author Lynne Olson describes how a group of young Tory members of Parliament, in May 1940, toppled the British Prime Minister Neville chamberlain, the leader of their own party, from power.
Chamberlain had an overwhelming parliamentary majority. He had declared war on Nazi Germany eight months earlier with the Nazi invasion of Poland. The young dissidents used a major British military setback in Norway, and the speech of the leader of their dissident group to motivate the British House of Commons to reassert itself as the guardian of democracy. The result was Churchill became Prime Minister May 10, 1940.
In the book titled Five Days in London May 1940, 1999, author John Lucas describes the five days Friday May 24, 1940 through May 28, 1940. On May 28, Churchill had won a struggle with his War Cabinet. He declared that England would go on fighting, no matter what happened. No matter what happened; there would be no negotiating with Hitler.
On page two, Lucas writes, “Then and there he saved Britain, and Europe, and Western civilization.”
In 1943 the United States War Department produced a factual film titled The Battle of Britain. In June 1940 the Nazi army had 100 fully equipped divisions lined 2,000 miles along the European coast, from Norway into France for the planned invasion of Britain. Britain had less than one equipped division. The Nazi air force out numbered the British air ten to one, both in aircraft, and in pilots.
I think Churchill satisfies  in no certainty,  in making a difference; and,  in justification with his personal commitment to resist the influence of his appeasers.
(3) if "option O will have the best outcome of all your available acts, then you are justified in doing O." It seems if it is a matter of doing something completely affecting yourself, seen in the Bank example, where staying in line would be the best option if stakes were high. If, on another example, say where your sister fell and broke her leg after falling through a crack in the middle of a frozen lake, the best option would be to bring her back before she freezes, taking the risk of walking across the lake (knowing there was a chance it would crack again). Even though stakes were high in this example, it seems the best decision would be to rescue her, whereas if it were a matter of walking across the lake individually, the best option would be to stay put. Perhaps I am missing the nature of the stakes, or the best option (or this may even be a question of ethics). Perhaps (3) is justified when only the individual is under consideration.