The idea that you should “just trust your gut” – that is, make many life decisions solely based on intuition (as opposed to based on reflection) – is obviously very popular. But I think that there are pretty much only four types of situations where we’re best off relying on intuition alone: when a decision is Fast, Irrelevant, Repetitious, or Evolutionary (FIRE for short).

Case 1: Fast decisions
There is no choice but to make the decision quickly, so thinking it through is infeasible. In this case, intuition is your only option because it’s the only method of deciding that’s fast enough.

Examples:
– the car barreling towards you in the other lane has just swerved into your lane
– you’re in a job interview and are asked whether you’d still be interested in this job if it pays less than your prior job
– the train you’re thinking of taking is about to depart, and there is no other train for five hours

Case 2: Irrelevant decisions
The decision is of low importance, so minimizing time, effort, and indecisiveness is more important than optimizing for the best outcome. In this case, intuition is your best option because it’s the least costly.

Examples:
– you are trying to decide whether to put carrots on your salad
– you are trying to decide what TV show to watch tonight
– you are trying to decide which $5 product to buy among several similar options

Case 3: Repetitious decisions
You have lots of experience making decisions in that realm AND received reliable information on how the decisions turned out. In this case, intuition is trustworthy because it’s been honed through practice with feedback.

Examples:
– a heart surgeon who is conducting her 500th heart surgery (but not a heart surgeon who is conducting her 2nd heart surgery)
– a digital marketer writing email newsletter headlines who has been tracking the performance of each such email for five years (but not one who doesn’t track the performance of the emails)
– a chess player making a decision about which move to make after playing chess daily for years (but not a chess player playing backgammon)

Case 4: Evolutionary decisions

It’s the sort of survival-relevant decision that our ancestors had to make regularly 20 thousand to 200 thousand years ago, and hence we should expect that evolution built us to have reasonable instincts in this domain. In this case, our intuitions are quite reliable: our genes endow us with these intuitions precisely because they helped earlier copies of our genes survive.

Example:
– should you eat that foul-smelling old food?
– is that person who has been staring at you likely to have malicious intent?
– should you walk on that injured knee that’s causing searing pain?

So, to recap, I think pure intuition is the right solution pretty much only for FIRE decisions, that is, those that are:

(1) Fast (because you don’t have time for anything else)

(2) Irrelevant (because the costs of other approaches are too high)

(3) Repetitious (because with lots of practice, when we’re receiving reliable feedback, our intuition becomes well-honed)

(4) Evolutionary (because certain types of decision-related instincts are built into our biology)

In other words, if you weren’t born with the ability to make the decision intuitively (non-evolutionary decisions), you didn’t learn to make that kind of decision intuitively (non-repetitious decisions), the stakes are high enough that it’s worth using the best approach (non-irrelevant decisions) and you have time to use another approach (non-fast decisions) then you should indeed use another approach.

So if a decision is not FIRE, you’re probably best off thinking the decision through carefully, discussing the decision with others, writing out pros and cons, etc. Intuition still plays a very important role in those cases, but it plays a supporting role (e.g., to help you figure out things like what you value, to help you estimate likelihoods, to help you synthesize lots of information into an overall judgment, etc.) rather than playing the only role.

I’ll emphasize since it is so important: intuition almost always plays a critical role in decision-making. The question here is just whether you’re merely (1) “going with your gut” (for the whole decision), or whether you are (2) feeding your intuitions (which might include intuitions about what you value, what you predict is true, what you feel, etc.) into a broader decision-making process.

I think that using just your intuition on important non-FIRE decisions tends to produce bad life outcomes.

So don’t just go with your gut. Go with your gut when your decision is FIRE, and otherwise, let your gut be a really useful tool, rather than letting it be in charge of the whole process.

Acknowledgments
Thanks to Sam Rosen for his help improving this framework. 

This essay was first written on April 7, 2019, and was first released on this site on August 30, 2021.

There’s a huge difference between riding on the back of a motorcycle once, and buying a motorcycle to ride every weekend, or between buying a cookie and buying a box of 25 cookies, or between taking a boxing lesson once and sparring regularly.

Unfortunately, our minds don’t necessarily give this difference between doing something one time and doing something T times appropriate weight. In many cases, the risk of the decision actually scales up proportionally to our prediction for T, the number of times we’ll do the thing. The problem is that how “significant” the decision feels to us may NOT scale up proportionally to T. So the “weightiness” of risky decisions can easily be miscalculated. We may be too worried about doing a thing once, and not nearly worried enough about doing it T times.

Consider the basic mathematics of repeated risks. When we do something that has pretty low risk “R” each time we do it (say, a 1 in 1000 chance of being seriously hurt), and the risk each time is independent of the previous times, then if we do it once we have a risk of R, whereas if we do it twice, we have two chances for the bad thing happening, so the risk is about 2*R. Likewise, the total risk we take on when we do it T times (for T not super large) is about T * R. This is the basic risk formula you should keep in your mind.

[A semi-technical side note for the math-interested: when we do the thing twice the risk of the bad thing happening the first time OR the second time if each event is independent is actually R + R – R^2. The R^2 comes about from considering the possibility that the bad thing happens both of the times. For intuition on this point, consider two circles that are slightly overlapping. To find the total area of the circles (i.e., the total probability of the events represented by the circles) you can’t just add up the two areas (i.e., add the probabilities), because you’ll double count the overlapping part (i.e., the part representing the event occurring in both instances), so you’ll have to subtract something away (the R^2 in this case, which has this form due to the assumption that the events are independent). However, if R is small, then R^2 is super small, so we can ignore it by assuming it’s 0; hence the total risk ends up being about 2R = R + R – 0. Therefore, the math mentioned above breaks down if you’re doing a thing with really high risk, or if you do the thing a large number of times relative to the risk level – this makes sense because if you have a 50% chance of dying each time then clearly if you do it four times you don’t have a 450% = 200% chance of dying. Likewise, if you have a 1% chance of dying each time and you do it 200 times, you also don’t end up with 1 %200 = 200% chance of dying. But for small, independent risks that you do a moderate number of times, R * T is a good rule of thumb.*]

So if you’re about to commit yourself to do a thing 30 times, you’re taking on about 30 times the risk compared to if you decide to do it once! Does your brain properly appreciate that huge multiplier? Do you feel on a gut level that doing something 30 times more often is 30 times riskier? Probably not. As the risk R gets bigger, a decision, of course, becomes more significant, but the actual risk is about T * R, so R is not enough to consider. If we mainly just consider R, then we probably end up too risk-averse on one-off decisions, and not nearly risk-averse enough on repeated decisions!

Let’s consider motorcycles. According to the National Highway Traffic Safety Administration, in 2006, you had, on average, about a 1 in 26,000 chance of dying for every 100 miles spent riding a motorcycle. For reference, this is 11x the chance of dying than a 30-year-old male has on a random day or 24x the chance of death that a 30-year-old female has on a random day.

So if you are considering buying a motorcycle, and predict you will ride it 100 miles each week for the next five years, that’s about 52 weeks * 5 years = 260 times that you ride 100 miles, so your risk of dying is amplified by 260:

R * T = (1 / 26000) * 260 = 1 / 100

That means you’ve just taken on a (predicted) 1% chance of death by buying this motorcycle! Of course, injuries are much more common than death (about 20x higher it seems), so the chance of injury you’ve taken on is much higher than that. So this is a very weighty decision. It becomes weightier still if you think you’ll ride it for ten years instead of 5. But even in the five-year case, consider: how much money would you pay NOT to have to roll a 100 sided die where death occurs if you roll a 100, and injury occurs if you roll, say, an 80 or higher? That’s the kind of die roll you’re taking on by choosing to ride a motorcycle 100 miles a week for five years.

[Note: sometimes, the risk PER time that we do something goes down the more we do it because we become more skilled. For instance, when we swim in the ocean as a weak swimmer, we are more likely to drown than if we do it as a strong swimmer. But then again, as a strong swimmer, we may take greater risks by swimming on stormy days, and as a weak swimmer, we may be cautious and stay very close to shore, so the risk per time on average could increase as we do it more. It’s hard to make a general rule about how the risk per time varies as you do something more often.]

Part of the reason we can underestimate risk is that we convince ourselves that we can stop at any time. For instance, we can buy a motorcycle and then later just decide to stop using it. Sure we can, but the question is, will we? We need to make the decision based on what we predict will happen, not what could theoretically happen.

The point is here that doing a “risky” thing once is far less risky than doing a risky thing many times (about T times more risky!), but your brain won’t necessarily perceive the right relationship. For small independent risks, the total risk of a bad thing happening scales with the number of times T you do the thing. So remember the risk formula: R * T, and teach it to your brain.

So I urge you: be appropriately wary of repeated risks! There are many things that are fine to do once that are a bad idea to do T times, for moderately large T.

If like most people, you think of yourself as continuously having free will in the future, you may have thoughts like:
(1) “I’ll have an hour to do this project tomorrow, so I don’t need to do it now.”
(2) “Once I’m back from vacation, I’ll start going to the gym every day.”
(3) “I don’t need to make this decision about where to invest my money now; I can make it at any time.”
(4) “I’ll choose not to eat these delicious cookies that I’m leaving out on the kitchen table.”

When you start thinking of your future self as having free will only intermittently, you instead ask yourself things like:
(1) “Do I expect that during that hour I have available tomorrow I’ll do this project? What does my past behavior imply about whether I will actually do it?”
(2) “Based on what I know about myself, will I start going to the gym daily when I’m back from vacation? If I had to bet money on it, which side would I bet on?”
(3) “If I don’t make this investment decision now, when do I predict I will make it? Will it be later this week, or more realistically, months from now?”
(4) “Even if I successfully avoid eating the cookies on the table a few of the times that I pass them, do I expect that I will avoid it every time? Or will I eventually give in and eat them?”

Additionally, when you think of yourself as having a reliably controllable free will for only the next 5 minutes, and start, therefore, viewing free will as precious, you may say to yourself things like:
(1) “Since I don’t actually expect I’ll spend that hour tomorrow doing the project, I’d better do it now.”
(2) “Since I probably won’t start going to the gym daily when I’m back from vacation as things currently stand, I’d better use the next 5 minutes to begin tweaking the situation to increase my odds of success, such as by picking the gym I’ll go to, and asking a friend that lives nearby if he wants to go to the gym with me regularly “
(3) “Since this investment decision will never feel urgent, I know I’ll probably by default put off making it for a long time, but since I don’t have time to make the decision thoroughly right now, I should set aside 3 hours on Saturday to do it, which I can block off in my calendar right now.”
(4) “Since I am in control of the decision right now, I should put the cookies into a jar that is out of sight, so that I won’t be tempted over and over again every time I pass the table.”

A second way to think of this:

If you almost always drink more than you want to when you go out with your friend Don, you’ll almost certainly do it next time, too, unless something about you or that situation is significantly different next time around.

More generally, if you almost always do action A1 in situation S1, why would you assume you’ll now instead do a different action A2 in the same situation? The fact that you can “choose” to do A2 instead of A1 is not convincing because last time and the time before that, you could have chosen A2 instead, but you didn’t, you chose A1.

The causes of you doing A1 last time will likely cause you to do A1 again. If you want to do A2 instead of A1, then you should do what you can right now (while you have awareness and control over the next 5 minutes) to change the future situation from S1 to S2, where S2 is a new situation that pushes the balance towards you doing action A2 instead of A1. It could be that the change from S1 to S2 is a change you make in the surrounding environment (e.g., moving the cookies), or it could be a change in yourself (e.g., reminding yourself regularly about why you care about going to the gym), but, whatever it is, it had better be a change. Otherwise, you’re stuck doing A1.

A third way to think of it:

It’s often useful to predict the behaviors of your future self, much like you’d predict the behaviors of other people, adopting the “outside view.”

You have 5 minutes of free will available to you right now, at this moment, if you choose to use it. It’s precious. What will you use it for?

So why do we behave in these strange ways? Well, here’s my list of reasons we so often fail to act in our own self-interest. As you can see, the reasons are numerous.

Note: the items listed are neither mutually exclusive nor collectively exhaustive. Some reasons are connected, and sometimes multiple reasons apply in the same scenario.

(1) Misinformation – believing an action is in your self-interest when it isn’t, or that an action isn’t in your self-interest when it is (e.g., taking useless nutritional supplements daily, because you’ve heard they are helpful but are unaware of the significant risk they pose to your liver)

(2) Temptation – choosing a tempting, short-term benefit over a larger long-term benefit (e.g., eating the chocolate cake that you know you’ll regret tomorrow)

(3) Avoidance – avoiding a certain choice based on its short-term consequences, even though it could be better for you long-term (e.g., staying in an unhealthy relationship to avoid a painful breakup)

(4) Anxiety – avoiding a beneficial action out of fear of possible consequences (e.g., avoiding public speaking opportunities because they cause anxiety despite enjoying public speaking overall) [This is similar to Avoidance, but different because Avoidance is based on a real consequence, as opposed to irrational fear.]

(5) Altruism – acting in a way that is beneficial to a person or cause but harmful to you in some way (e.g., donating a substantial portion of your income to an effective charity) [this is a positive reason but included for comprehensiveness] 

(6) Forgetting – simply not remembering to act on something that is beneficial (e.g., forgetting to take your medicine)

(7) Confusion – not knowing how to carry out a beneficial action properly (e.g., you want to lift weights weekly to be healthier, but do not have sufficient training on the correct form to avoid injury)

(8) Distraction – intending to carry out a beneficial action but getting sidetracked during the process (e.g., sitting down at 6 pm for daily journaling but being called away to help your child)

(9) Delaying – pushing a beneficial action into the future since it has no clear deadline (e.g., you know you really should get treatment for your sleep problems that are ruining your happiness, but you’re busy and plan to address it next month)

(10) Helplessness – you’re convinced that attempts to take a beneficial action will inevitably fail, so lack the motivation to try (e.g., you feel that you’re dumb and will get bad grades no matter what, so you feel unmotivated to try in school)

(11) Unmotivated – knowing a certain action is good for you, in theory, but not feeling driven to do it (e.g., you know your current job is not a good fit for you but never feel motivated to search for a different one)

(12) Habits – you fall into harmful, subconsciously triggered routines of behavior or perpetually behave in a way that inhibits beneficial outcomes (e.g., you have a habit of fixating on negative traits of other people, and this makes it hard to develop deep friendships)

(13) Unequipped – you lack the ability or resources to carry out a beneficial action due to a lack of practice or training (e.g., you know it’s important to communicate honestly with your romantic partner, but struggle to put your thoughts and challenges into words)

(14) Love – making a sacrifice for a person with whom you have a close personal relationship (e.g., a parent who works an extra job so as to send their child to a better school they couldn’t otherwise afford) [similar to altruism, but more personal than acting out of general goodwill]

(15) Punishment – you punish yourself because you feel you deserve it, or to harm others indirectly (e.g., a teenager who engages in self-harm because they believe they are worthless or because they know it upsets their parents)

(16) Overwhelm – you have too many choices or too much information related to a certain action, so you shutdown or stick with the first or easiest choice (e.g., you know you should carefully select details of your 401(k) plan but, after reviewing three dozen options, you get frustrated and leave it at the default setting)

(17) Reactance – you resist outside efforts to control you (e.g., an employee who intentionally takes three cups of coffee per day in order to flout the two cup limit)

(18) Freedom – you choose to act contrary to your self-interest solely to demonstrate (to yourself or others) your freedom to choose (e.g., a person who makes a minor bad decision to show they could do so any time, if desired)

(19) Impulse – you feel a strong, subconscious-rooted urge to carry out certain harmful actions (e.g., a person who feels a strong urge to curse constantly)

(20) Expectations – you are expected to or pressured to act a certain way, and you are either used to satisfying expectations or desire social acceptance (e.g., an unbelieving person attends weekly religious services long-term solely because the community views them as devout) 

(21) Over-optimizing – you expend so much time, attention, or effort toward improving on a process or decision that you end up losing more than you gained (e.g., someone who changes projects every year because they want to find the very “best” project but actually accomplishes little because the projects are all left unfinished)

(22) Fatigue – you do not have the cognitive resources to make a good judgment at that moment [resulting from lack of sleep, burnout, drugs, etc.]

(23) Misjudgment – you misjudge the relevant probabilities or values involved in a choice and so choose the wrong one (e.g., making a bad stock market investment because of misanalysis of the relevant factors) 

(24) Uncertainty – you avoid options that are uncertain or ambiguous because certainty makes you more comfortable (e.g., someone who passes on a new interactive theatre experience, something they have no previous experience with, to instead watch a movie they’ve seen fifteen times)

(25) Inertia – you stick to the decision you previously made, or the path you’re already going down, even though it is clearly no longer beneficial (e.g., you’ve finished the first year of law school and, even though you don’t like it or want to be a lawyer anymore, you don’t withdraw) 

(26) Haste – you make a decision under time pressure and therefore don’t consider all the options or don’t consider the options thoroughly enough (e.g., a deer runs into the road, and you decide to swerve left even though it would have been a lot safer to swerve right)

(27) Prioritization – you expend effort or resources to make good decisions in some areas but not in those that are less important to you (e.g., a person chooses to focus their entire energy on getting healthy but neglects interpersonal relationships)

(28) Morality – you think it would be immoral to take the action that is most in your self-interest, or you feel guilty thinking about taking it (e.g., you really want a stereo and know you wouldn’t be caught stealing it, but you won’t take it anyway) 

(29) Emotion – you are experiencing intense emotions that alter your perception of what a good decision would be (e.g., you are really pissed off, so you punch the person that you’re talking to)

(30) Complexity – the decision is too complex for you to reason about effectively or too different from previous decisions you’ve made for your intuition to be reliable (e.g., you’ve just been elected president, and now you have to make decisions involving hundreds of factors and hard to predict second-order effects in areas that you’re not an expert in)

(31) Identity – you think of yourself as the sort of person who does X, so you choose to do X to maintain this self-identity or as a shortcut in decision-making (e.g., a person who thinks of themselves as a non-drinker and so doesn’t even consider the option of drinking in cases where they could potentially benefit)

(32) Attention – you make self-harming decisions because you want others to notice you, step in to help you or show that they care (e.g., a person who burns themselves with cigarettes so that others will notice the burns and feel concerned)

(33) Myopia – you think that your options are more limited than they are or you fail to fully consider what your best option is (e.g., you quit your job because you think of your options as either “stay” or “quit,” whereas you would have actually been better off renegotiating your role without quitting)

(34) Normality – you don’t want to take any action that may be considered strange, odd or weird (e.g., even though you are confident you would be better off having an open relationship rather than a monogamous one, you would not consider it because in your culture that would be a “strange” lifestyle)