6 signs you can’t trust someone

Lessons from a former FBI counterespionage chief.

by Robin Dreeke and Cameron Stauth
Last Updated: 30 Jan 2020

When dealing with new people, leaders will invariably need to interact with people they don’t trust, for the obvious reason that you can’t fully trust someone you’ve never met before.

This new person - a potential new hire, supplier or business partner perhaps - may have a great reputation, a sterling resume and a record of success, but these qualities can be contrived.

As a result, new relationships are often guided mostly by intuition, along with facts from the past and the opinions of others. 

The problem with this is that it’s hard to read people and accurately predict what they'll do. That’s not because we're all compulsive liars or have rapidly shifting personalities. It's because most of us hide or disguise the parts of our lives that we don't want others to see – particularly if there's something important at stake, like love, money, our careers or our reputations. Even good people feel the need to hide things, because nobody's perfect, and everybody's vulnerable. 

Fortunately, there’s a better way to determine quickly whether you can trust someone, based on the social science of behaviourism. It is a system that consists of six basic, rational principles that fit most situations and derive from one essential truism of trust: people will almost always want to act in their own best interests.

When you know what they want, you will generally be able to predict their behaviour. And when you can predict their behaviour, you can usually trust them to do what is in their own best interests. Trust in practice, therefore, is not a matter of morality, but of predictability.

The Six Signs that Reveal Predictable Behaviour:

1. Trustworthy people believe that their success is linked to your success

This is arguably the most important sign, because you can almost always trust people to do what's in their own best interests. But some people think that self-destructive acts are in their best interests. So for positive behaviour, sign #1 must usually be accompanied by sign #6 (below). If both signs are there, you can predict that they'll be trustworthy.

2. Trustworthy people believe that they will be with you for a long time

If they do, it's in their best interests to treat you well, because nobody wants a long-term adversary. We all feel more secure in relationships that last, so you can usually trust long-term associates, as well as family members, to stay loyal, just as they can trust you. At work or at home, the only thing better than a friend is an old friend. They are the most predictable people you know. So if what you see tells you that someone is considering a future that doesn't include you, watch out. You can predict a different relationship ahead. 

3. Trustworthy people are reliable: a combination of competence and diligence 

Too many people exaggerate their abilities and resources, even when they're not trying. Competence is a deal-breaker - you may trust your husband, but not enough to let him fly a plane - but competence without diligence is worthless. Diligent people are persistent, thorough, motivated and responsible. They come to work early and stay late. Work is the great equaliser: even when reliable people are struggling, you can predict that they'll soon thrive.

4. Trustworthy people show consistent past patterns of positive behaviour

Trust leaves a trail. If you don't see it in somebody, take another route. Actions speak louder than bragging (although bragging can sometimes get pretty loud). So when you're sizing someone up, call people they know, check their claims and find out if their closest allies also succeeded. If they didn't, you can predict a similarly rocky road for yourself.

5. Trustworthy people use key words and phrases that communicate trust

The language of trust that you're looking for is all about you, not them. Untrustworthy people might send you an email without any of these first-person words: I, me, my, mine and myself. The people you can trust are all about: you, your, yours and yourself. Once you get to know them, hopefully they'll say: we, ours and ourselves. They don't debate, get defensive, sound scripted, criticise others, or hide behind political correctness. They rarely use absolutes - such as never, always, every time or none - because absolute truths are quite uncommon. Sometimes you can predict someone's behaviour the first time you meet them, just by how they talk.

6. Trustworthy people are stable

They're hard to scare, impeccably rational, appreciative, generous, happy with themselves and those close to them, flexible, friendly, balanced and calm. They try to shine with solutions, rather than gain attention with problems. And they are almost never self-destructive. You can trust them to not bring themselves down, and take you with them. You can almost always predict that once you trust them, you will almost always be able to.

This system was created as a mechanism for revealing people who were involved in counterespionage activities, and also for recruiting trustworthy people. It has worked in a diverse range of situations within the US Federal Bureau of Investigation, and within many American corporations.  

If you need to depend upon someone, apply these six predictors of predictability, and you'll find that the process of probing people's personalities is not as difficult as it once may have been.

Former FBI agent Robin Dreeke and writer Cameron Stauth are the authors of Sizing People Up: A Veteran FBI Agent’s User Manual for Behaviour Prediction

Image credit: Noam Galai/Getty Images


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