About once every other week or so I am contacted by someone who wants to raise capital, but does not want to describe their business to me.  They're nervous about their idea being stolen. 

As you can imagine it's very difficult to decide to invest in an idea that you haven't heard, forcing either the entrepreneur to take a risk and give their pitch or me to pass on the opportunity (at least until the entrepreneur is ready to share).  If a VC and entrepreneur can't discuss the idea in relative detail, they'll be at an impasse - wasting both parties' time.  For this reason VCs generally expect entrepreneurs that reach out to them to be prepared to readily share information. 

The idea of sharing information with a VC that will not sign an NDA can present a significant quandary for an entrepreneur that needs money but is nervous about sharing their idea.  The good news for the entrepreneur is that this problem has been dealt with and overcome daily for decades.  The bad news for the entrepreneur is that the way to break this stalemate is for the entrepreneur to take a risk and share their idea with the VC.

There are a few reasons why an entrepreneur should feel at relative ease with taking the leap and pitching their idea to an investor that they may never have met before. 

1. This is the way business is done at the early stage.  The best VCs may be speaking to as many as several hundred entrepreneurs a month who are all pitching their ideas to the VC without having an NDA in place.  In a nutshell, this is a commonplace risk to take and a standard part of the the startup process.
2. Good VCs understand that the reputation and therefore their career as an investor relies on their adhering to a code of ethics. My post The Venture Police:  Reputation addresses the risk a VC faces for acting unethically.
3. VCs hear great ideas every day.  While an entrepreneur may believe that their idea is the greatest concept since the steam engine, VCs may hear ten other ideas of equal caliber that month.  If a VC were to steal an idea (which is very very rare), the odds are low that it would be yours.
4. Very simply, good VCs are not in the business of stealing ideas and are far too busy to do so if they wanted to.  Investors are in the business of backing companies, not running them.
   

With few exceptions, experienced entrepreneurs readily share their ideas.  In fact, not sharing information is traditionally viewed as a sign of inexperience.  By-in-large this is because experienced entrepreneurs understand the rationale listed above.

At the end of the day if you want to raise money you need to be prepared to share your business plan.  If you're not ready to do that yet, keep your head down and develop your company to the point where you are comfortable discussing it.