To Joseph Priestley
London, September 19, 1772
Dear Sir,
In the Affair of so much Importance to you,
wherein you ask my Advice, I cannot for want of sufficient Premises,
advise you what to determine, but if you please I will tell you how.
When these difficult Cases occur, they are difficult chiefly
because while we have them under Consideration all the Reasons pro and con
are not present to the Mind at the same time; but sometimes one Set
present themselves, and at other times another, the first being out of
Sight. Hence the various Purposes or Inclinations that alternately
prevail, and the Uncertainty that perplexes us.
To get over this,
my Way is, to divide half a Sheet of Paper by a Line into two Columns,
writing over the one Pro, and over the other Con. Then during three or
four Days Consideration I put down under the different Heads short Hints
of the different Motives that at different Times occur to me for or
against the Measure. When I have thus got them all together in one View, I
endeavour to estimate their respective Weights; and where I find two, one
on each side, that seem equal, I strike them both out: If I find a Reason
pro equal to some two Reasons con, I strike out the three. If I judge some
two Reasons con equal to some three Reasons pro, I strike out the five;
and thus proceeding I find at length where the Ballance lies; and if after
a Day or two of farther Consideration nothing new that is of Importance
occurs on either side, I come to a Determination accordingly.
And
tho' the Weight of Reasons cannot be taken with the Precision of Algebraic
Quantities, yet when each is thus considered separately and comparatively,
and the whole lies before me, I think I can judge better, and am less
likely to take a rash Step; and in fact I have found great Advantage from
this kind of Equation, in what may be called Moral or Prudential Algebra.
Wishing sincerely that you may determine for the best, I am ever, my dear Friend,
Yours most affectionately
B. Franklin
Source: Mr. Franklin: A Selection from His Personal Letters. Contributors: Whitfield J. Bell Jr., editor, Franklin, author, Leonard W. Labaree, editor. Publisher: Yale University Press: New Haven, CT 1956.
