You could adapt some of Hobbes's arguments from Leviathan to oppose anarchism. I suggest you go read the first book at the very least.

Now if we look at anarchism in the sense of a complete lack of state, where everyone acts out of a sense of unity. A very idealistic idea.

However, quite a few problems arise once you start looking into it. For example, the issue of justice. How will that be carried out on criminals? One way we could do it is to have the people decide. I don't think I need to tell you why that would be a terrible idea. The other way would be to have the people choose someone who can carry out the duties of justice. A little better, but that still doesn't guarantee his competence, nor the fairness of the sentences.

Another problem also arises. What's to stop people from coming together and establishing their own government. In order to ensure that gangs or vigilante armies don't arise, we would need a police force. But then who should we expect to join the police force? Certainly not volunteers. It would end disastrously. We can only hope to acquire qualified police officers. But then who would lead the police force? Will we have the officers choose? Perhaps that may work if they pick someone competent. But then, who's to say that leader won't abuse his power? We need someone to be able to keep an eye on him. And if he does do something horrible, who will be able to stop him? Will we have to rely on the other members of the police force to kick him out? What's to stop them from doing so regardless of what the leader was doing? We thus need someone to ensure that nothing terrible will happen in the police force. We thus need either multiple police institutions, or a higher power to keep them in check. In the first case, we would need to organize them. Who will organize them other than some form of government? If we pick the second option, we would need something resembling an army, or a national guard. Who would organize the men with weapons?

Then there's also the problem with the organization of the agricultural fields. Who would transport them? The farmers? Are we to except all the farmers living in the world TODAY to all use their own trucks to bring to a market? Perhaps that is viable, but it would be terribly unorganized.

Then there's the issue of trade. How would people acquire necessary goods? Surely with either money or traditional trade. If we were to use money, where would said money even come from? Without a governmental institution to keep track of the printing of bills, who could we rely on to stop us from reaching over-inflation?

Then there's the issue of national defense. Are we to assume that wars will simply stop if there's no government? Of course not, it would simply encourage them. What happens when people don'T have enough resources in an anarchist society? Do they simply let themselves die, or would they rather take what their neighbor has? Then who would defend the anarchist society? The people? Would we have them all live in constant anxiety of knowing that they're expected to risk their lives for petty squabbles between communes? I don't think that should be seen as an ideal.

Anarchism might have worked in a time where populations were small and economics were simple. But today, there's simply too many people in the world to assume that people would all be good in the name of ''unity'' and of ''the society''.