False. Libertarian "doctrine" agrees with the assertion of the Founders that our Rights (especially those to Life and Liberty) are unalienable. One always has the right to enter into contracts for services, but such contracts may also be terminated when and if they become unstaisfactory. A contract freely entered into, even for provision of long-term service, does not constitute slavery: one essential element of slavery is that it is involuntary from the slave's point of view.