How do you break a deadlock when both founders disagree on a major call?

Me and my partner always thought we’d just talk things through whenever big decisions came up.

But when we hit our first huge disagreement it completely stalled our progress for weeks.

It turns out agreeing on everything in the easy early days is dangerous if you haven't assigned who gets the final vote in specific areas like product vs business.

Do you guys set hard decision rules from day one or just resolve ties as they happen?