The taking of a life is not immoral.

Humans are programed to want to forward the species, not the opposite. Therefore, it is immoral to kill because it is the opposite of human nature.

Fallacy Of Is To Ought

Just because humans are (possibly) programmed not kill each other, it does not follow that they ought not to.

There should be a market for organs (both organs of deceased and extra organs of living, like kidney)

It is an entirely non-consensual practice that would effectively force those living in poverty to surrender their internal tissues at steadily lesser prices.

Fallacy Of Slippery Slope

Its a fallacy to say that because poor people could sell organs that they would compelled to as well. Some certainly may choose that it would not be worth.

The US should repeal the 16th amendment to remove federal income taxes and instead implement the FairTax.

It forces the burden of taxes to fall equally on the poor as the super wealthy; and it is therefore a step backwards into further inequality. With great power comes great responsibility, and power is wealth in a capitalist society. Only progressive taxes are therefore just.

Appeal To Belief

Saying only progressive taxation is just implies the belief that the government has the moral support to tax in the first place.