Where Logic Ends
Even after logical reasoning narrows down choices, multiple plausible options often remain; making a decision then requires additional axioms, heuristics, or time pressure.
THE IDEA
WHERE LOGIC ENDS
Even when we have decided on our logical starting points, or axioms, there might be situations where they don’t fully determine what decisions we should make. Imagine choosing from the following menu at a restaurant.
Marinated Roast Breast of Chicken – £18.50
with caramelised pineapple, coconut sauce and wild rice
Pan Fried Ostrich – £21.00
on a bed of ratatouille with a rosemary and redcurrant jus
Char Grilled Fillet Steak – £26.95
with stilton and red wine sauce
Smoked Haddock Fish Cake – £16.95
with spinach, poached egg, sorrel sauce and fries
Roasted Summer Vegetable Tart – £17.95
with truffle oil dressing
All main dishes are served with a medley of fresh seasonal vegetables
Perhaps you’ve decided that you can’t spend more than £20, and also you don’t like fish. This logically narrows down your options to the chicken and the vegetable tart, but beyond that, logic can’t tell you anything. It would be actively illogical to choose the ostrich at this point, but would it be fully logical to choose the chicken? I would call it logically plausible rather than fully logical.
One of the reasons that making decisions is hard is that in most cases logic narrows down the possibilities for us, but several plausibly logical choices still remain. Life is very complicated and much of it is unknowable, with the result that we often end up in situations that logic can’t completely decide for us, and it’s easy to get stuck in indecision.
To make the decision we can do several things. We can try to add more axioms to the system so that the logical choices are narrowed down to one. For example, we could decide at the last minute that in the absence of any other preference you’d like to try something you’ve never had, and that means caramelised pineapple. Or you might decide to have the cheapest thing that fits your needs, which would be the vegetable tart. Or you might decide to somehow think about which one sounds the most appealing, by seeing which one makes your mouth water when you think about it. Or you could toss a coin.
Sometimes I’m unable to decide until the very last second, when the server has taken everyone else’s order and if I wait any longer I’ll just be causing an obstruction. A time pressure is one of the things that helps or requires us to override logic, because logic is too slow.
When to use it
Choosing a meal when multiple menu items meet your dietary restrictions and budget.
Selecting a job offer when several positions are equally good on paper.
Deciding between two similar products that both satisfy your core requirements.
Picking a vacation destination when several options are affordable and appealing.
FROM THEORY TO EVERYDAY LIFE
In practice
Restaurant Menu Choice
After applying budget (under £20) and dietary preference (no fish), logic leaves two options: chicken and vegetable tart. Without further criteria, logic cannot decide between them. Additional axioms (e.g., 'try something never had' or 'choose cheapest') or a coin toss are needed.
Time Pressure in a Queue
When a server is waiting for an order and the decision must be made quickly, time pressure overrides the need for logical deliberation, forcing a choice even if it isn't fully reasoned.
A MOMENT TO REFLECT
Put it to work.
Think of a recent decision where logic narrowed down your options but you still felt stuck. What additional rule or heuristic helped you choose?
How does the presence of a deadline (time pressure) change the way you make decisions? Does it make you more or less satisfied with the outcome?
Can you recall a situation where you added an arbitrary 'axiom' (e.g., 'I'll pick the first one I see') to break a deadlock? How effective was that?
CONTINUE THE CONVERSATION
Source texts
- The Art of Logic How to Make Sense in a World that Doesn’t (Eugenia Cheng)