Why Logic Alone Won’t Lead to Good Decisions

When one businessman lost his ability to feel emotions, his work started to collapse. Neuroscience explains why.

Why Logic Alone Won’t Lead to Good Decisions
[Image: Flickr user Bob MacInnes]

As you may know from Star Trek, Spock is half-Vulcan and Vulcans are purely logical: they don’t let fluffy stuff like emotions get in the way of making coolly rational choices.


But here’s a counter-intuitive truth, care of neuroscience: emotions are essential to making rational decisions.

Highly illogical?


In his book Descartes’ Error, neuroscientist Antonio Damasio describes Elliot, a patient who had it all; he was a successful businessman, a good husband and father. Then he developed a tumor in his brain that had to be surgically removed. It resulted in damage to a part of the brain associated with emotion, called the ventromedial frontal lobe.

Soon, Damasio says, Elliot became an “uninvolved spectator” in his own life: Even though his marriage collapsed and each business venture folded, he remained controlled. Damasio spoke with Elliot for many hours, but he never noticed sadness, impatience, or frustration.

Nor did he see any decisiveness. Small choices like which pen to use, when to make an appointment, or which restaurant to eat at led to circling deliberations.

Which, curiously enough, sounds a lot like a decision-making meeting run purely on logic. As Damasio writes in Descartes’ Error:


In the high-reason view, you take the different scenarios apart… and perform a cost/benefit analysis of each of them. You infer logically what is good and what is bad. For instance, you consider the consequences of each option at different points in the projected future and weigh the ensuing losses and gains.

Sounds great, right? A Spock-like precision of decision-making, clean of the messiness of emotions. The only problem is that it won’t work. As Damasio continues:

At best, your decision will take an inordinately long time, far more than acceptable if you are going to get anything else done that day.  At worst, you may not even end up with a decision at all because you will get lost in the byways of your calculation.

This is because, he says, you will not be able to hold in your head all the pluses and minuses your deliberation demands. Because attention and memory have limited supplies.

So what could accelerate that process? What could make those cost calculations go faster? Why, it’s that stuff that the Vulcans are so reasonably unburdened by: emotion.

Why You Need Emotions To Make Decisions

It’s a function of your gut: when you’re looking a few possible courses of action, you get a feeling about one versus another.

Rather than scrutinizing every item of every menu, your feelings about what you’d like to eat allow you to skip over the pizza that you aren’t in the mood for. Similarly, your emotions help you with your career: if the thought of spending hours a day coding gives you the heebie-jeebies, then perhaps it’s best to avoid the developer bootcamps you’ve heard so much about.


In this way, emotions don’t get in the way of making smart decisions, they’re an integral part of that process. Another reason why emotional intelligence predicts job success.

Sorry, Spock.

Hat tip: Ed Batista

About the author

Drake Baer was a contributing writer at Fast Company, where he covered work culture. He's the co-author of Everything Connects, a book about how intrapersonal, interpersonal, and organizational psychology shape innovation.