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Company Brain and context

What is a Second Brain? Definition and examples

Also: Personal knowledge management, PKM

In short

A Second Brain is a personal system in which one person captures notes, ideas and knowledge to take the load off their own memory. It helps the individual. A Company Brain, by contrast, is the shared memory of a whole company.

Why it matters: Personal order is good, but a company's decisions need a shared memory.

Second Brain

For one person, private, unreviewed

Company Brain

For the company, shared, approved

Second Brain and Company Brain compared

Why does Second Brain matter for your company?

Many leaders keep a Second Brain in note apps such as Notion. It holds meeting notes, ideas and decisions. For the person that is valuable; for the company it stays invisible.

With AI the difference grows. A personal AI assistant knows its owner's Second Brain; the teams' AI agents do not. What a company has decided together therefore belongs in a shared memory, not in private notes.

Example: The CEO's notes

The CEO keeps a careful Second Brain. It records why the company focuses on the DACH mid-market and plans no US expansion. Her personal AI assistant answers questions about it; the team and its AI agents know nothing of it.

She moves the decision “Strategy 2027” with its reasoning into the Company Brain. Her private thinking stays in the Second Brain; the shared decision is visible to every person and AI agent. The two systems complement each other.

3 common mistakes to avoid

  • Turning a Second Brain into the company source

    Personal notes are neither reviewed nor approved. Teams should not work from one person's private collection.

  • Recording company decisions only privately

    What leadership decides belongs to everyone who works from it. In a Second Brain it reaches nobody.

  • Playing one against the other

    A Second Brain does not replace a Company Brain, nor the other way round. Personal thinking and shared decisions need different places.

Step by step

  1. 1

    Separate personal from shared

    Ask of every note: does this concern only me or the company?

  2. 2

    Share decisions

    Move decisions with their reasoning into the shared memory.

  3. 3

    Link instead of copying

    Your Second Brain holds a link to the shared state, not a copy.

Bring one important decision.

In 30 minutes with Marc or Simon we show where your work drifts from the decision today.

Meet the Company Brain

Read on in the PM Lab

Articles that go deeper.

Build · Live ViewClaude Code for Product Managers: the Setup That Turns a Chat Window Into a ColleagueMost product managers use Claude Code like a better search engine. What separates that from a real colleague isn't a better prompt – it's a set-up workplace: context, assignment, eyes, review, routines and permissions. This piece walks through the setup step by step.Read the article Define · PrioritisationBuild your own company brain: the enterprise AI playbook from Stripe's engineering teamStripe gave 10,000 employees powerful agents without turning them into AI engineers. The ten decisions behind Kai: one company layer, projects as governance, skills as company IP, sandboxes, and the infrastructure underneath. And what the same architecture looks like for a software product team.Read the article

Related terms

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