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Benjamin Franklin’s rule for decision making

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Ben Franklin had views on how to make a decision. In a letter to Joesph Preistley, he wrote

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

A fair bit of academic research has been done on the quality of Franklin’s rule for making decisions. See for example:

* Gigerenzer, G. & Goldstein, D. G. (1999). Betting on one good reason: The Take The Best heuristic. In Gigerenzer, G., Todd, P. M. & the ABC Research Group, Simple Heuristics That Make Us Smart. New York: Oxford University Press.

* Czerlinski, J., Gigerenzer, G., & Goldstein, D. G. (1999). How good are simple heuristics? In Gigerenzer, G., Todd, P. M. & the ABC Research Group, Simple Heuristics That Make Us Smart. New York: Oxford University Press. [Download]

For analysis of an even simpler, unweighted variant, see:

* Dawes, R. M. The robust beauty of improper linear models in decision making. American Psychologist, 1979, 34, 571-582.

Source of Franklin quote: There is a copy of this quote online at http://www.procon.org/view.background-resource.php?resourceID=1474 which cites:

* 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.

Image credit: http://en.wikipedia.org/wiki/Benjamin_Franklin_Medal_%28American_Philosophical_Society%29


  1. Johann says:

    For interesting discussion of Franklin’s method see http://bit.ly/aRWNGR

    August 21, 2012 @ 5:35 am

  2. Franklin's rule as a car salesman's tactic | Decision Science News says:

    […] response to last week’s post about Franklin’s rule, your loyal Editor’s mother sends along this passage from the story “Can I Just Sit […]

    August 23, 2012 @ 4:24 pm

  3. Jeanja says:

    Another difference is that Dawes had human experts determine the direction of a cue– a positive or negative unit weight– while the later papers used the data to determine direction (specifically cue validity > 0.5 meant a positive weight).

    August 23, 2012 @ 9:34 pm

  4. Benjamin Franklin’s rule for decision making | | Decision Coaching - Ursina Teuscher, PhDDecision Coaching – Ursina Teuscher, PhD says:

    […] taking Dan Ariely’s recent blog post as an opportunity to revisit a classic – a letter by Benjamin Franklin, in which he describes […]

    August 24, 2012 @ 2:50 pm

  5. Jamie Weiss says:

    Franklin’s method does have a couple of pitfalls –
    – It asumes that the Pros, or the Objectives, that drive the decision are as important as the Cons, or Risks, overall, and that, case by case, is not necessarily so. (A company in ‘Hail Mary Pass’ mode, just trying to survive, may have greater risk tolerance than a more established firm with more to lose.)
    – While “Weighting’ is a great idea, and the KT process uses it extensively, we use it differently, in terms of weighting the “Importance’ of the various objectives, where Franklin uses the Weights more as Scores of Performance, thereby opening the way for decisions in which an alternative scores well on the ‘bells and whistles’ but poorly against the handful of critical criteria that drive the decision. Since all criteria are equally important, no criterion is important;
    – Finally, weighing the Cons, or Risks, in how they ‘cancel out’ the Pros might make sense, but only if they are causally linked. If the Con of ‘this model of car tends to break down a lot’ cancels out the Pro of ‘excellent warranty coverage’, that’s one thing. But we feel you can get further with Risks by looking at their Probability and their Seriousness separately, since one will bias you toward Preventive Actions, to remove the threat, and the other toward Contingent Actions, which may mute its impact, giving you a more balanced risk management attack.

    August 29, 2012 @ 3:30 pm

  6. Benjamin Franklin’s rule for decision making says:

    […] a letter to Joesph Preistley, Franklin wrote: …To get over this, my Way is, to divide half a Sheet of Paper by a Line into two Columns, […]

    September 18, 2012 @ 9:01 am

  7. Mark says:

    … or you could just use this site where Ben Franklin’s method is implemented online.

    November 10, 2016 @ 9:00 pm

  8. shelby says:

    make them clearer to read
    Example: Have a title labeled RULES and them list them in bullet point.

    December 18, 2016 @ 2:33 pm

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