What is the reason for taking your position on Abortion?

My father and I were in conversation, when it turned to the dark side for a few minutes.

"Why are you willing to side-step choice and force a woman to carry the child to term?" (me)

"You know, a million fetuses are aborted annually. And if the were born instead..." (him)

"Wait a minute.  That does not answer the question."

"Sure it does.  Abortions in this country reduces the number of taxpayers in the future.  If those  are not born, grow and develop, and pay their taxes, then the government cannot pay its debts."

I do not know what is worse; force a pregnant woman to carry to term or force a person, who was forced to be born, to pay taxes, to a government under which he or she lives." (me)

He was adamant.  What fallacy does he offer?

"Sure it does.  Abortions in this country reduces the number of taxpayers in the future.  If those  are not born, grow and develop, and pay their taxes, then the government cannot pay its debts." 

No offense to your dad, but this answer is almost comical for several reasons. First, viewing this issue without compassion for either the unborn or the woman - just as a financial transaction. Second, he completely overlooks the fact that abortions also reduce the number of resource consumers. As a non-economist, I can't make a well-supported argument as to why a smaller population is better, but I am quite confident the financial burden of unwanted children is far greater on a country than what they would pay in taxes.

I don't see a fallacy on your dad's part; just a wild opinion. I don't think your dad avoided the question; he did provide a reason (i.e., the tax-payer reason was why he is willing to side-step choice).

Appeal to consequences is the only fallacy that he may be appealing to.  The rightness or wrongness of the matter is being decided by it's consequences when these are not morally relevant.

I say may, because it may be that he does really believe the basis of morality is the interests of the State.  In which case it isn't a fallacy to appeal to consequences at all. 

Trouble is that appeal to consequences is more about truth than morality.

The anti-abortion argument here seems to be:

P1: Allowing abortions will reduce population

P2: Reduced population will have fewer tax payers

P3: Fewer taxpayers will reduce government income

P4: Reduced government income will mean government cannot pay its debts

P5: Government not being able to ay debts is a bad thing.

C: Therefore, we should not allow abortion.

To me, the logic seems OK, except that perhaps he's cherry picking when it comes to the potential results of allowing abortions – his examples all relate to the benefits of additional people and ignores any problems associated with more people.    

As well, I'm just not sure that I can buy into the truth of all of the premises.