Do you rely on proof or belief?

“It doesn’t matter what I believe. It only matters what I can prove.”
— Lt. Daniel Kaffee, A Few Good Men (1992)

In a court of law, and when dealing with the finance department, they’re only interested in what you can prove.

But if you’re operating in complexity, or creating something that doesn’t exist, you need to stand on belief.

Belief and Proof are both valid forms of understanding, but they come from very different places.

Proof feels safe and reassuring. Proof relies on external evidence, documentation, and artefacts. It shows up in project plans, dashboards, and reports, making it easy to show that progress is being made.

Belief on the other hand is subjective and relational. It comes from connecting with others. It is the ‘gut feeling’ about what is really going on. Belief is how you make judgement calls about a course of action even when the path isn’t clear.

Proof can be manipulated

Bent Flyvbjerg in Top Ten Behavioural Biases in Project management: An Overview warns that business cases, particularly for large projects, are profoundly compromised by a range of behavioural and political biases.

The apparently objective approach gets distorted by these unseen biases you can end up with overly ambitious targets and flawed timeframes. You’ve probably encountered situations where the numbers are made to create a good enough return that supports a decision to proceed.

And once the project gets going, the regular status updates can "prove" progress by ticking off tasks, but still miss whether the project is genuinely moving towards its intended outcome.

Numbers might feel reassuring, but they’re a poor guide when facing complexity. Just look at any project promising improved revenue numbers that went live in February 2020, just as the world went into lockdown.

Belief holds uncertainty

Belief is tacit, and we often don’t know why we believe something, but we trust our gut that it’s true.

For example, managers may disagree on whether allowing more sick leave would undermine productivity. Since neither side can definitively prove their case because the result depends on the reaction of the front line, the managers must stand on a belief of what the workers would do, shaped by assumptions about culture and intent.

You don’t have to completely resolve the questions because belief gives you the confidence to make decisions in ambiguity rather than being paralysed by the uncertainty of the situation.

However, belief requires judgement. It can feel scary. It takes time, patience and experience to build, and it depends on the situation and your connection to it. Any calls made without this relationship to reality are hubris or just a guess.

What do you prefer?

Proof can be logical and wrong. Belief can be debated.

Proof might not be as powerful as you think it is. The power of belief depends on who you are talking to.

Proof looks backward and tries to infer forward. Belief imagines a future.

So what do you prefer?

It is ineffective to make decisions in complex environments if you don’t have a sense for how the wider system operates. If you’re writing business cases for operational change but haven’t spent time in the operation (not just observing it, but breathing it in), then your assumptions will be unreliable.

In complex projects, you can’t wait for evidence before moving forward. You often act on belief and let the proof emerge over time.

The art lies in holding both – using proof where possible but recognising that belief is what sustains momentum.

This raises a few questions:

1. Are you waiting for proof that may never come?

2. Is there something you believe to be true but are not moving on?

3. Are you relying on metrics that provide a false sense of security?

4. Where do you need to build more connections to truly understand what's going on?

Find the balance

When making decisions, create space to include both methods of understanding.

Ultimately, proof answers "what is," while belief fuels "what could be".

Do your homework. Get the facts to prove your position because finance will always want that. But also get close to the action, immerse yourself in the frontline activities and environment so that you create the connections and build useful beliefs.