Why is libertarianism so infallible?

Libertarianism is the inclusion of every sapient being into the decision making process and all that logically follows from that. Utilitarianism is the objective of ensuring the most happiness for all sapient beings and all that logically follows from that. Sometimes they compliment each other, other times they contradict.

Discuss.

I think that about covers it. Libertarianism is infallible as it is the product of politic science worked logically from empirical facts and clear inductive reasonning without unnecessary emotive language or cult-like ideals. The only argument against it is the same argument against scientific method, that it is not the certain truth but rather we have no choice but to be libertarian since that is the most logical conclusion given the facts.