Instructions from your boss, the idea to build a new website, the new business model you have been gnawing at, that new product you wish to create – all have one thing in common. Gray.
You don’t know everything – rather, let me rephrase – you can’t know everything ab initio. There will be information black-holes as you set out on your endeavor. People develop different tolerance thresholds to tackle this phenomenon. They mentally set their GAB (Gray Acceptance Bar) as they navigate through the initiative and have made a-priori decisions of when to plunge and how much to commit. They will not break out of the inertia until their GAB levels are breached. This is natural.
It is useful to remember that ideas that spawn activities are rapidly reducing their gestation periods (the community website I am planning for different stakeholders in software product development has possibly germinated in another hundred minds as you read this). He who gets off the blocks sooner has a higher probability of learning-on-the-go and hence succeed.
Most people set their GABs rather high (different reasons – intertia is often not directly penalized, fear of failure, inability to make assumptions for critical yet missing information and the likes). My advice to Product Managers, Architects and entrpreneurs in general is to keep a low GAB and get ahead in the race.