The Content Wrangler

The Content Wrangler

Glossary

What Is A Deterministic System?

How to document the rules, inputs, and conditions that cause software to produce a predictable result

Scott Abel's avatar
Scott Abel
Sep 10, 2026
∙ Paid

Deterministic system (noun)

A system whose rules produce the same output whenever it receives the same inputs under the same operating conditions.

About Deterministic Systems

Deterministic systems follow rules that determine what happens. Start with the same state, feed in the same inputs, and the system applies the same rules, resulting in the same result every time.

A calculator is the simplest example.

Enter 10 × 5 and you get 50, every time.

Software permissions work the same way. If access depends on a user's role, subscription level, and security settings, the system reaches the same decision whenever those values match.

Same inputs covers more than what our users type in. It includes things like account settings, stored data, software version, current time, feature flags, and information pulled from connected services. Change any one of those inputs, and our result can change too.

What Makes A System Deterministic?

User's avatar

Continue reading this post for free, courtesy of Scott Abel.

Or purchase a paid subscription.
© 2026 Scott Abel · Privacy ∙ Terms ∙ Collection notice
Start your SubstackGet the app
Substack is the home for great culture