There will come a time when your brightest, most beloved employee will want to leave. Reid Hoffman says you should let her go—or at least, in many instances. On July 8, the king of social networks himself, who founded LinkedIn and was an early investor in Facebook, will publish a radical book of advice for managers called The Alliance, and it’s worth a read. A follow-up to his 2011 blockbuster The Start-Up of You, this instructional manual makes a strong case that managers should rethink the very essence of the relationships they strike with employees. Along with co-writers Ben Casnocha and Chris Yeh, Hoffman argues that no one goes to work for one company forever anymore, and that managers shouldn’t pretend they do. Instead, employees and employers should agree upon short increments of work to accomplish together much like a military tour of duty. Once the work is complete, they should meet to reevaluate what happens next. I recently sat down with Hoffman, who joined the prominent Silicon Valley VC firm Greylock Partners in 2009, to discuss how his ideas translate into practice. Below, our conversation (edited for clarity):

You discuss thinking about increments of work as tours of duty, a term you take from the military. How do you convey that to employees?

You should actually have conversations with your employees to say, what would your dream job be, whether it’s here or somewhere else? How do we align our interests where it’s working for both of us that you are on your path?

That’s easy when an employee arrives knowing what she wants to do, but very often people don’t. They arrive wanting a job.

They want a job and they want success. They want some notion of, “I’m making progress.” You want to align that instinct to things that are very helpful to the company. The classic thing for decades was: Be a good company person. And sometimes it plays out that way. But what you want to do is say, we are much happier when you’ve made a huge amount of progress. If the consequence is you stay at the company, that’s okay. And if the consequence is, you move on, that’s okay too. We want to make that all very healthy.

So you’re encouraging potentially talented people to leave?

If that’s what’s right for them. One consequence: companies are generating a lot more young alumni than they used to have. It used to be that alumni were 65 and played golf. Now you have alumni who worked here from age 25 to 30 and are now doing other things. How do you stay engaged with those alumni and how is that helpful to you?

You talked about John Donahoe and eBay as a good example. How did that work and what have the results been like?

The eBay alumni network runs a set of services—the most prominent is events—where they invite alumni back to the events to keep a relationship going with the company. You never build a relationship with a “give me something.” You just build the relationship and good things come out of them. I think they have alumni referring new employees. They’ve gotten intelligence about how technology is evolving and how eBay should react. They’ve hosted a dinner with some of the Paypal folks, for example, to say, how do you think Paypal should evolve? Where are payments going?

You talk about attempting to codify the relationships that people in your organization have with outsiders. You give some examples of that. How does this work at Greylock?

We publicize in a huddle on Monday morning, who are all the different people that folks are meeting with this week? Then [if there’s a relevant fact or relationship to bring up] people say, “This would be something useful for you to know.”

There’s a constant pressure on workers to prepare themselves for the jobs of the future without abandoning the jobs they have; at the same time, because they stay in jobs for shorter periods, they often have less opportunity for professional development. How do people prepare?

In terms of professional skills it’s no longer useful to think about the industrial model. I train and train and then I am ready. Rather, it’s like agile programming—continual adaptation. There are two forms of continual adaptation. The first is picking up intelligence on the job. [And that can happen in lots of ways.] For example, you can expense a lunch meeting and bring intelligence back to the organization. The second way skills retraining happens is in more bite-size chunks that occur in a much more adaptive and ongoing way. Instead of, say, going to business school and returning, [employees can learn] in conferences and briefings…. Two-week classes, for example. You can easily see professional certifications happening via remote learning over the Internet.

Why did you write this book?

There’s an underlying broken notion in thinking about how an employer and an employee relate to each other. The breakage goes to two factors. One is, “well we’re still doing the lifetime employment of all the people we like”—wink, wink, nudge, nudge. In that conversation, the company and employee are lying to each other. Both know that’s not the modern world. We’ve swung to the opposite extreme of one-day employment contracts, where either side is ready and willing to cut off the relationship whenever convenient. The lack of trust hinders innovation and long-term collaboration.

What do you want people to take away from it?

Part of living in the networked age is there are always a bunch more smart people that you don’t know than you do know. The question is, as a manager, how do you navigate your group to take advantage of that fact. One trade-off of having some people move on is good: bringing in new blood. That brings in a whole raft of new information, network access, changes in what’s going on. It’s also good to have people you have good relationships with go to other places because when the relationship continues, that becomes an intelligence stream back.

The career, then, is a combination or products, not a series of titles. People have this model of thinking about the progression of careers as a ladder of titles. That ladder of titles now means a lot less. What actually matters is a sequence of projects. The Alliance says, here is a way you can manage groups and people on sequences or projects where you can accomplish great things.

So what as a manager can you do for your employees? You can’t guarantee them lifetime employment, but you can give them lifetime employability. That’s when you have been awesome to your people.