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MVP philosophy and the Justified True Belief


Lately I have been listening and reading about philosophy and I came across a theory that got me thinking about hypothesis driven development, Minimum Viable Product (MVP) and validation.

It is accredited to Plato from around 369 BC with the name of Justified True Belief. The writings about it goes into much deeper philosophical exploration, but I took the liberty to simplify it and bring to my Lean Inception world.

You can only affirm something to be true if:
– You believe that it is true
– You can validate that it is true
– It is true

´You believe that it is true.´ Basically you have to formulate the statement for a belief about something being true. For example: I believe I will sell more products if I change the color of the ´Buy Now´ button from blue to yellow.

´You can validate that it is true.´ Here is when you plan to validate it, You work your hypothesis so it can be proven with some evidence. For example, I perform AB testing with the blue and yellow buttons and collect metrics on how much sales are performed by each button color.

´It is true.´ The original belief (yellow bottom will sell more) has been validated. The collected metrics provides evidence on it.

I am by no means capable to carry on the philosophy explanation on this theory (in fact, you can find more philosophers, like Voltaire that took it further with great texts and thoughts around this topic).

But I like some of the Vein diagrams I found on the reading about this topic. So, I created my own to explain it in the lenses of Hypothesis driven development, MVP, and Lean inception (the workshop that triggers this kind of conversation).

Let´s get started.

Anything is either true or false. This is simple. Difficult to disagree. In the orange circle, everything that is true; outside of the circle, false.

Now let´s consider the beliefs. In the blue circle are the things you believe to be true. Outside of the circle are things that you believe are false.

Now let´s talk about validated things. In the pink circle are the validated stuff. Things that have been validated. There are numbers, metric, evidence that bring some light (validation) to it. Outside of the circle, things that have not been validated.

I hope I still have you with me. So far so good. Simple circles. It is either inside or outside. True or False. A Belief or not something you have formulated any belief. Validated or Not validated.

Now let´s look at some combination of two of these circles.

Some things you believe to be true are really true. Others are false. The point is how to figure out if something you believe to be true is really true or not?

If you don´t do anything about it, it is only an opinion, a supposition, your belief about something being true. You might be right, you might be wrong.

If it is really important to you, you have to find a way to validate it; which brings us to another combination of two of these circles.

You have your belief that something is true. And there are the results, the indications, the indisputable evidence that shows very clear: it is true or it is false.

You should find a way to validate your belief. In the Lean Startup, Lean Inception, and Hypothesis driven development world, it has a name: the Minimum Viable Product (MVP): the simplest way for you to validate your hypothesis, your belief.

In our example: I will build a simple feature that shows either a blue or a yellow ´Buy Now´ button on the product page (each time the product page is rendered, it shows a different button color). I will also build another feature that tracks the number of sales per button color

The result: a validated belief. You have built the MVP, the minimum thing to validate your belief. You got the results, the evidence. Now, and only now, you should bring the three circles togetehr (finally the Justified True Belief, the three statements presented earlier: I believe it, I validate it, it is true!)

Now let´s look at all of it together. These circles from a Vein diagram. They are all interconnected, and it will bring quite a few interesting areas for us to talk about.


H. Everything that is False.

G. Things that are True. You don´t believe they are true. And there is no validation about them.

E. Things that you believe to be true, but are false. Unfortunately, there is no validation of it.

F. Things that were validated to be false. Although you have never formulated any hypothesis or plan to validate them. You did not believe them to be true.

D. Things that you believe to be true, and are true. Unfortunately, there is no validation. You only have assumption, there is no evidence that proves you are correct

B. Things that you thought were true but are false. You were able to validate them as false. You have gained great knowledge. Your belief was wrong. you can change it. In Lean Startup jargon, you should pivot.

C. Things that were validated true. But they were validated by chance as they were not in your belief. You have never formulated any hypothesis or plans to validate them.

A. Things that were validated to be true, and you thought it would be true. You have formulated a hypothesis, a plan to validate them. You did it and now you got evidence on it. You have gained great knowledge (your belief was right. you should go deeper, explore it further!). Here is the so desired spot, the justified true belief. You believed it, you validated it, it is true. Well done!

But why did I get into this philosophical conversation and colourful vein diagram?

As a Lean Inception facilitator, I bring a group of people along to better understand their beliefs and how to validate it.

There is no silver bullet. It is not like you have a belief and magically you will prove you are correct, it is true. It is not like you have an idea and magically it will work, and your product or solution will be a great success.

You have a great idea, you have to formulate the vision and how you will validate it. You need to align and decide the MVP.

The MVP is exactly for this means. It helps you validate your idea. It will take you from the Belief only area (E) into the Validated Belief area (A and B)

You create the MVP and get the usage data, the learning and the metrics that help you validate your hypothesis. You get evidence if your belief is correct or wrong (areas A or B on the diagram). And this is exactly what you need to move forward. You must evolve your product and solution based on justified true belief.

You have a belief? Then you formulate the MVP, build it, and get evidence to validate your hypothesis. If the result is on the B area (ops it is not true), you pivot, you try again, until you get it in the center, in the A area (the justified true belief: belief, validated, true!).



Paulo Caroli

Paulo Caroli is the author of the best-selling book “Lean Inception: How to Align People and Build the Right Product” (the first on a series of books on business agility). He's also the creator of FunRetrospectives.com , a site and book about retrospectives, futurospectives and team building activities. Caroli writes on this blog frequently. Receive the next post in your email. Sign up here.
Lean Inception: Learn How to Align People and Build the Right Product

Lean Inception: Learn How to Align People and Build the Right Product

Lean Inception is a crucial agile methodology for aligning teams on effective product creation. Introduced by Paulo Caroli, it combines Design Thinking and Lean StartUp techniques to define strategies and Minimum Viable Product (MVP) scope. It is valuable for large projects, startups, and business innovations. Not suitable for discovery activities, prototyping decisions, or cross-team alignment. Active participants, stakeholders, and skilled facilitators are essential for the success of this collaborative process. Lean Inception is fundamental for guiding teams toward meaningful and efficient product outcomes.

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