The fool never does what the wise judge wise, because he does not follow up the suitable means. He that is discreet follows still less a plan laid out, or even carried out, by another... let him that has not decided attend rather to what is possible than what is probable.
Baltasar Gracián, 1647 (tr. Joseph Jacobs, 1892)
Two cautions sit in this maxim. The first: do not assume your opponent will do the sensible thing, because fools do not follow the wise course and even clever rivals deviate to surprise you. Planning around what your opponent "should" do leaves you exposed when he does something else. The second is the deeper one: attend to what is possible, not only what is probable. Most people plan for the likely case and are undone by the unlikely one that they judged too improbable to prepare for. The discreet person keeps one eye on the possible, the low-odds outcome that would hurt the most, because it is the possibility you dismissed, not the probability you expected, that tends to arrive.
Practice
- Do not build a plan that only works if your opponent behaves reasonably; assume he may do the unexpected and cover for it.
- Alongside the probable case, list the possible ones, especially the low-odds outcome that would cost the most, and prepare a first move for it (maxim 151 rehearses the trouble).
- Keep your own method unpredictable; a plan the rival can anticipate is a plan he can counter (maxim 17 varies the mode).
Use this when
- Use this in negotiations, competition, and any adversarial situation where assuming rational opponents can leave you exposed.
- Use it in risk planning; the possible-but-improbable disaster is exactly the one most plans skip.
Ignore this when
- Don't drown in every conceivable possibility; prepare for the possible ones that would actually hurt, not for all of them (maxim 24 keeps imagination supervised).
- Don't treat allies as enemies to out-guess; this is for adversarial ground, not for the people you build with.
A picture of it
A small firm plans its pricing on the assumption that its larger rival will behave rationally and never drop below cost. It builds the whole year around that probable case. The rival, fighting for market share and not for profit, does the irrational thing and prices below cost for two quarters. The firm that had prepared only for the probable is caught flat; a competitor who had asked "what is the worst possible move they could make, and what would we do?" had a plan ready, a niche the price war did not touch, and came through the two quarters intact.
Plan for what the rival could do, not what he should. The possibility you dismissed is the one that arrives.