Right-libertarians, the Fair Tax, and big government

I begin by identifying right-libertarians as individuals who believe, foremost, that legislators should reduce the size of the national government. A number of right-libertarians support a Congressional tax reform proposal, the Fair Tax. This support is surprising because the bill is revenue neutral : it therefore does not directly address concerns over increasing Congressional spending or growth of government. Are right-libertarians sacrificing their principles for expediency or is there some other explanation? I argue right-libertarians mainly support the bill because they (1) believe Congress would abolish the IRS as soon as it went into effect, increasing citizens' privacy in the process ; and (2) view it as a gradual reform that would lead to further legislation intended to reduce the size of government.