All you have to do is look at the empirical evidence. Successful single-founder startups are so rare that they're famous on that account.
I'm not saying that having a cofounder is so important that you should take someone lame, or someone you don't know well. Maybe if you can't find a cofounder you're just screwed; I don't have enough data yet to say for sure. But someone going into a startup as a single founder should be aware they're doing something that, for whatever reason, rarely works.
If you look at the empirical evidence, you will see that most successful companies are started by an individual. Now, of course, a successful company needs more than one person to be involved-- they need employees. And early employees can be very well rewarded and significant contributors to shaping the idea.
But leadership by consensus does not work, as anyone who has belonged to a high school club or organization knows. In a business environment, it is death- the founders never reach consensus and generally they constantly pull against each other, undermining each other and ultimately undermining the company.
Leadership by consensus is quite literally the absence of leadership.
When there is a leader, and that leader is capable, the company succeeds.
If you have a pair of people who work well together, then as you concede generally one of them will be the clear leader. Dividing the work and having each lead sections of the company is fine- if you know the person who you can do that with. But such people are generally quite rare.
Unfortunately, the advice that you must find a founder in order to start a company is bad advice-- in most cases this will lead to the company failing. There are, of course, examples of pairs of people who co-founded companies together and they are well known because they are the exception. But the vast majority of successful american enterprises are started by an individual with an idea and the dedication to pursue that idea.
Forming a company takes vision. It takes dedication and it takes certainty that there is something there- and opportunity to add value that has not already been seen and seized by other entities.
This is why leaders who start companies are far more likely to success than friends who decide to "do a startup" and "manage by consensus."
If you don't have a cofounder already- you shouldn't be looking for one. Hire some employees.
But you're far from screwed-- simply looking at the history of startups in America and you'll see that single men with vision are most often the ones who succeed.
Worked for us at Viaweb and Y Combinator. Works for most of the 58 startups we've funded.
And btw, you're misinterpreting my analogy about the plane, but I'm out of stock on "no, what I meant was" so I'll leave it as an exercise for readers who care to figure out how.
I'm sure concensus management has worked for you-- never said it didn't and haven't said its impossible. However, the problem is that you're saying people must have a co-founder, and that they must manage this way... and there's a big difference between having a cofounder you've known a long time and getting a cofounder because you foolishly followed the advice of a self styled guru.
If my response seems harsh, its because your tone is pretty strong. If you expressed your opinions in terms of preferences it would be one thing-- but you lay them down and defend them like they are religious law, and do not respond to the fact that this religious law does not work in all situations... which brings us back to the plane analogy-- its great for trying to make me look stupid, but its piss-poor (actually irrelevant) for arguing against what I was actually saying.
Secondly, while I agree with you that if you planned everything by yourself and are willing to do it alone, you shouldn't just look for co-founder when you can start implementing by yourself with some employees. But I got to warn you that's pretty extreme and may get you looking like a 70 year old when you are 25 very fast, because of the exhaustion it causes to run a big venture by yourself.
I don't know statistics either and I would like to put  everywhere I look on the internet but a two men team has more potential on the long run then an one man army because the two founders motivate each other, share problems and have a larger knowledge base to solve them, make it more fun and pleasing to work on a startup.
I like your post because you raze awareness regarding the importance of having good cofounders. Anyway some people like to work alone one and they do it better that way, but I think most men might fall apart on such high pressure, especially if they don't have previous experience in making startups.
One more thing is that it's very hard to find good employees that are willing to work at a startup, even harder to pay them while you don't have any revenues in site.
No need to warn me, I've seen the strife of having co-founders, and I've seen the harmony of having a solo found er and co-founder teams that lasted 20 years.
I don't think its a factor of finding "good" co-founders. I think unless you have known the person a long time, you can't know if they are "good" or not- its not whether they are good or not, as the most earnest, responsible, loyal and considerate founder may still be the death of your company. Its fundamental to the nature of trying to manage a company by consensus.
Consensus management doesn't work- or we'd be up to our ears in all the communes the hippies started in the 60s and 70s.
Q: In an underpowered twin, what is the role of the second engine?
A: It doubles your chance of engine failure, and it will fly you to the scene of the accident.
Most of the companies you've worked for had multiple founders - to be get big enough to hire someone is a measure of success. I think history likes to write stories about single men of vision - especially in the established business fields. I'd take such a look with a healthy skepticism.
But my point is that there has to be someone in charge. You can have "cofounders" so long as they know that the buck stops with you. (Or you can be a cofounder so long as you know the buck stops with someone.)
You can see why I might get that impression...
Can you point me to any studies about the failure rates of startups? anything that's not anecdotal or personal experience?
However, you can look at any list of the richest people, or any list of successful startups, and you'll note that most of them were founded by individuals. Though you gotta restrict your data to companies that have lasted a decade or so- otherwise you havent' given the founding teams time to split apart.
I can imagine a Kirk-Spock sort of startup, where one person excels at making decisions and doing the legwork, and another at providing information and skills.
I suppose, in practice, few people can trust someone else to make all the decisions, especially if it's their future on the line. What's your experience been?
I should hope not. There has to be a unified vision of some sort. I'd like to point everyone in the direction of the Fred Brooks presentation from OOPSLA: http://www.oopsla.org/podcasts/Keynote_FrederickBrooks.mp3
Doesn't the same argument apply to successful_ startups founded by 20-somethings? I.e. they are famous because they are so rare.
_My definition of successful is taking the company public.
Paul, would you agree that a co-founder makes many things easier, but the right single founder can find that support structure through other means (e.g., spouse and a few core employees with significant stock)?
Anything short of a Wozniak will not do it.
Anyone in disagreement can go and ask Jobs.
What do you have in mind that can be built almost entirely in Facebook and expanded later on? I suppose if I think hard enough I can come up with some long shot ideas that may or may not work out (product-rating apps which could be expanded to include other social networks, for one), but even something like this is going to require some kind of heavy backend analysis to be especially useful. Keep in mind that we're also ignoring the (very real) possibility of Facebook sweeping in and mirroring any successful application or approach to generating revenue.
On another note, what makes Facebook any easier for experimentation than Apache? Writing scripts that print pages to a browser is as easy as writing to standard output.
How many web 2.0 companies do you know that are pulling those numbers?
Facebook is the most viral platform in the history of man - making it easy to get a lot of users quickly makes it deal for experimentation.
Going back to amichail's original comment, the implication was that making Facebook apps is really easy, and therefore a cofounder might be less necessary. The only point I was trying to make was that any Facebook app that is going to be really easy to make is unlikely to be a big revenue generator. My assumption was that any app that was going to be big enough and useful enough to generate good revenue was going to require a significant backend external website to crunch numbers and store relevant info.
So what's the point of what I'm saying? I was trying to counter the idea that building a revenue-generating Facebook app would be any easier than building an independent site. In both cases, you have to build the backend, anyways. So then we're merely talking about the difficulties of building the interface, and I was saying that it's not that hard to do with Apache and a script in just about any language: just print what you want the browser to see to standard output. Even if building a Facebook interface is easier, that is fraught with other complications (such as worrying about Facebook itself doing its own, official version of your app).
So in the end, I'm saying that building a successful Facebook app is not much different from building a successful website, so if you need a cofounder for a website, then you also need one for the app.