Give at least four reasons why we should or shouldn't still have a
government and taxes?

For questions priced $10 and above, you don't have to say "please" (but most do).
Read the text book; there may be a summary at the end of the chapter(s).
Read your lecture notes.  (The four reasons I can think of might not
be the right ones.)
You are taking an "economics course".

I agree with myoarin there, but if you're still stumped, try to
brainstorm about possible reasons...

-Think of the functions of government. In fact, some of those
functions are clearly outlined in the US Constitution.  What might
happen in the absence of a government?

-Even though many have argued that taxes are a burden, what would our
economy look like without them? America didn't always have a national
income tax. Why do you think it became necessary to have one? While
many argue we could do with less government (what they really mean is
lower taxes), there are clearly many things that only a government can
provide, and taxes are the only sensible way to fund those activities.
 Just look at America's enormous defense budget. There is practically
no way to fund our defense without taxes.  Even if you take a "bare
bones" approach to government and argue that the sole purpose is to
provide for the common defense (and some have argued that), a country
would still require lots of taxes.  And even though lawmakers on both
sides of the political aisle have argued about just what is important
to fund and what is not, the fact is that there has never been a
budget that Congress approved that was smaller one year than the
previous. In fact, Congressional appropriations are really simply
incremental increases, the true debate being just how much to increase
the budget and where.  (Although individual programs may be cut, there
are always increases to offset those cuts and so budgets always
increase year-to-year).