This line of defence may, as against Home Rulers, be disposed of at once by an argumentum ad hominem.  No politicians have made freer use of prediction.  Every Gladstonian speech is in effect a statement that is a prophecy of the benefits which Home Rule will confer on the United Kingdom.  Gladstonian anticipations no doubt are prophecies of future blessings; but whoever foretells the future is equally a prophet, whether he announces the end of the world or foretells the dawn of a millennium.  And history affords no presumption in favour of the prophet who prophesies smooth things.  The prognostics of a pessimist may be as much belied by the event as the hopes of an optimist.  But for one prophet to decry the predictions of another simply as prophecies is a downright absurdity.  Even among rival soothsayers some regard must be had to fairness and common sense; when Zedekiah, the son of Chenaanah, smote Micaiah on the cheek, he struck him not on the ground that he prophesied but that his gloomy predictions were false.  Zedekiah was an imposter, he was not a fool, and after all Micaiah, who prophesied evil and not good, turned out the true prophet.

But an argumentum ad hominem is never a satisfactory form of reasoning, and it is worth while considering for a moment what is the value of prophecy or foresight in politics.  Candour compels the admission that anticipations of the future are at best most uncertain.  Cobden and Bright foretold that Free Trade would benefit England; they also foretold that the civilised world would, influenced by England’s example, reject protective tariffs.  Neither anticipation was unreasonable, but the one was justified whilst the other was confuted by events.  All that can be said is that on such anticipations, untrustworthy though they may be, the conduct no less of public than of private life depends.  Criticism on anything that is new and untried, whether it be a new-built bridge or a new-made constitution, is of necessity predictive.  But there is an essential difference between foresight and guessing.  The prevision of a philosophic statesman is grounded on the knowledge of the past and on the analysis of existing tendencies.  It deals with principles.  Such, for example, was the foresight of Burke when he dogmatically foretold that the French Constitution of 1791 could not stand.[108] Guessing is at best based on acute observation of the current events of the day, that is of things which are in their nature uncertain.  On January 29, 1848, Tocqueville analysed the condition of French society, and in the Chamber of Deputies foretold the approach of revolution.