Almost all software engineering systems are reversible. If a decision can be unmade later I find is a lot easier to accept committing to a decision despite not yet being 100% confident it's the best approach.

This works in collaborative decisions too: if someone still has doubts, ask them to "disagree and commit" to the new direction but promise them that you'll evaluate if it is working out in a fixed time period - drop something on the calendar in two weeks time for example.

Indecision paralysis is much more harmful to a project then picking an option that later turns out to be suboptimal.