This question always spurs an interesting debate. Specially when the individual concerned has the skills to build a business himself, but realizes that getting another person to join in will help liquidate his/her stake in the company. I believe both sides can be argued for. A lot also depends on the circumstances, and type of business that one is starting. However, in most circumstances, I would tend to favor having a co-founder, rather than going it alone. Some major reasons for this are:
1. The ability to convince one, or more, smart individuals to help build your company, validates your idea to a certain degree. If you are a sole founder, this is something that you will not always be able to assess, which leaves one in a vacuum, assuming that the concept is going to be the next big thing!
2. By doing it all oneself, we sacrifice the ability to excel at one thing. Each of us has one or a few core strengths that we excel at. By having co-founders who complement us, we can develop our strengths, with our partners neutralizing areas we are not so strong in. This helps form a stronger and more cohesive team.
3. Building a company from scratch is extremely tough. We need someone there to lean on, often just provide support when the chips are down. When stuck in a predicament, a co-founder often helps us see the bigger picture, and bounce off ideas.
4. When you want to raise funding for your startup, VCs and investors strongly favor funding teams, rather than sole founders. From the investors point of view, a team has the potential to get a lot more done as compared to a single person. In addition, the pressures of a startup, make it a risky investment as a sole founder set-up only.
The main challenge is finding the right partners. Partnering with the wrong person, will negate all the above points , which will in turn start to work against us, placing us in far more vulnerable positions. I always follow my 8 point checklist when evaluating new partners. It has been a great help to me.
What do you think? Do you think going it alone is the answer? Why?