A recently published book brings hypotheses to bear on history. What if this country had not declared war (a majority in the cabinet were opposed) on Germany in 1914? What if we had lost the Battle of Britain 27 years later?
In a rather less serious conjectural vein, where would Manchester United be now if they had acted on a campaign launched against Alex Ferguson in 1990 by disaffected supporters?
Events make it easy for many among the Old Trafford faithful to forget that they once wanted rid of the man who is now established beyond all reasonable doubt as one of the great football managers.
Confirmation of this, by which I mean the disaffection that grew up around Ferguson, is contained in another recent publication, United We Stood by a 26-year-old educated type, Richard Kurt, who apparently gave up a teaching career to concentrate on facetious appraisal of Manchester United's fortunes.
An elongated fanzine that too eagerly embraces the genre's dodgy enthusiasm for urban xenophobia, Kurt's book carries the following reaction to Ferguson's most difficult season at Old Trafford:
"Winter approached, the nights grew darker; United got worse and the knives were getting sharpened. Of course, there were still odd moments of iridescence when some of the team's donkeys managed a good game and the team showed their potential... these were not common sights at the time. But what we were getting used to was watching United slip slowly down the toilet as the New Year hove into view. Possibly the worst was the game against Spurs at home; humiliated three-nil, we jeered them off the pitch and vented our rage at the manager and chairman."
As those awful football phone-in programmes have proved, you would not hang a dog on the word of a supporter but, to be fair, where was the cunning and wisdom that Ferguson brought to bear at Aberdeen when breaking the Celtic-Rangers duopoly in Scottish football?
Kurt continues: "The `Fergie Out' campaign had begun in earnest, seemingly started by a bloke in J-Stand who just couldn't take anymore and rapidly taken up by K-Stand and the rest; banners began to appear and `Fergie Out' hit the top of the terrace hit parade... we might as well admit it - most of us wanted Alex out.
"If the rest of the stadium needed further convincing, December did the job. Not a win in seven games; we failed to beat any of the four London sides we faced in consecutive games; Fergie dropped [Mark] Hughes for the Palace game and we lost it... that match seemed to symbolise the malaise we were in. Mystifying selection by a manager who had bought a load of expensive parts for a machine that he did not know how to assemble."
Looking back now, recalling the pressure Ferguson was under - one respected critic referred to his appointment as an unmitigated disaster - the probability is that a 1-0 victory at Nottingham Forest in the third round of the FA Cup saved him. "The sense of the time was that a knock-out by Forest would release the Edwards butcher's chopper," Kurt adds.
"Now, of course, everyone claims that there was never such a possibility, that the Cup run didn't save Fergie's career and that the board would have stood by him throughout. Pardon us for not swallowing that one whole."
Even when Manchester United defeated Crystal Palace in a replay of the FA Cup final, doubts about Ferguson still lingered. In common with all who had succeeded Matt Busby his task was not merely to produce a consistently successful team but maintain the sense of style for which the club was internationally famous.
Ferguson still had to run for daylight. Winning the European Cup-Winners' Cup in 1991 gave him room for manoeuvre but a great deal more was expected, most obviously the championship after almost 25 years. Then came the disappointment of finishing second to Leeds United in 1992.
Events since then have been testimony to Ferguson's perception and perseverance. Four out of five championships since the Premiership's inception, two more FA Cup victories, the Double twice.
Towards the turn of the year I put it forward that the signings Ferguson made last summer suggested more Scottish thrift than shrewdness. He took me to task over this, pointing out that he had tried to sign Alan Shearer. So what if the Newcastle and England forward had chosen Old Trafford over St James' Park? Would Ferguson now be reaching out for the one great prize that still eludes him?
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