It's hard to identify where to start this critique of such an absurd line of reasoning from those who hail from such prestigious institutions of academia. The initial premise of any "tax cut" is especially fallacious considering tax rates were being held constant on income were they not?
One must have a solid understanding and theory of property rights in order to first argue anything related to taxes. Individuals own the rights to their body and more importantly to the labor they employ to live the life they choose so long as such employment of using one's labor does not HARM others in the process.
When individuals employ the use of their labor to produce/transform material into goods or services, one can conclude individuals have inherent property rights to said goods based on the prerequisite the exchange and acquisition of property was voluntarily made and considered just (without theft or obtained through nefarious means).
The government, however, cannot acquire anything without first TAKING from sovereign individuals through taxation, borrowing from future taxation, or devaluing the monetary medium of exchange (otherwise known as inflation).
As Murray Rothbard correctly stated:
Taxation is theft, purely and simply even though it is theft on a grand and colossal scale which no acknowledged criminals could hope to match. It is a compulsory seizure of the property of the State’s inhabitants, or subjects. (The Ethics of Liberty, p.162)
A "tax" for all intents and purposes is always destructive since it much come from the productive and private sector. Taxation (especially taxation on one's income) is a coercive act executed by the government whereby already earned income of productive individuals is seized.
Thus, what the government chooses to SPEND through its various outlays is the only real COST the government need concern itself. If the tax revenue coercively taken by government fell by 50% and spending was cut by 50% (assuming a balanced budget), would the government NET have any budgetary issues? Of course not!
Yet, we are presented with the universal canard that income and property earned by private individuals first belongs to the government. Shame on those in positions of influence who continue to propagate such lies which are a direct threat to the individual/economic liberty and prosperity of free people.