The article shows that different methods of valuing companies using cash flow give the same result. The disagreement comes from how tax shields are calculated. There are 7 theories on this, with Myers' method giving inconsistent results. The value of tax shields is not just the tax savings from debt, but the difference in taxes paid with and without debt. Taxes paid without debt are less risky. The formulas for valuation change when debt's market value differs from its book value.