On this, realists and liberals agree. The anarchic nature of the international system strongly affects state behavior, and is unavoidable.

This again refers to the difference in what each school of though defines as the ultimate goal of states. Because realists perceive security, by way of power, as states' ultimate goal, they don’t desire cooperation: they simply want to maximize power relative to their rivals so as to increase security. Liberals, however, reject security by way of power as an ultimate end, and thus hold cooperation to be a virtue.

Realist international relations theorist Kenneth Waltz summarizes this difference well in Man, the State, and War:

This is a situation in which we have not just a pie to divide but the problem of how much pie to make as well. Under these conditions the game can tend to ward either of two extremes. (1) It may become a simple problem in maximization: all the players may cooperate to make the largest possible pie. In international politics this corresponds to the hypothetical case in which all states band together with nature as their adversary. (2) All the players may be so intent on the question of how the pie already in existence should be divided that they forget about the possibility of increasing the amount each will have by working together to make more of it. Instead of a simple maximum problem, the game then reverts to a zero-sum or constant-sum game. In international politics this corresponds roughly the the situation now prevailing, in which two sides have ormed and the gain of one side is often considered to be the loss of the other.

This is particularly true when there’s a handful of businesses with a GDP surpassing many countries'.

Realists deny the influence of such organizations mainly because they don’t maintain militaries, and realists often measure power in terms of military might. However, liberals don’t view power as the ultimate end which states seek like realists do, and thus this does not discredit the role of these organizations to liberals.

This is an important qualifier. Many Americans believe that the proxy wars fought during the Cold War were liberal, ideological wars “all about promoting democracy and human rights”. Realists argue that these proxy wars were merely part of a larger security competition with the Soviet Union.

Macroeconomist Dambisa Moyo researched and reported on this notion:

People now believe that democracy is no longer to be viewed as a prerequisite for economic growth. In fact… it’s economic growth that is a prerequisite for democracy. In a recent study, the evidence has shown that income is the greatest determinant of how long a democracy can last…

We should be worried about going around the world and shoehorning democracy, because ultimately we run the risk of ending up with illiberal democracies, democracies that in some sense could be worse than the authoritarian governments that they seek to replace.

The evidence around illiberal democracies is quite depressing. Freedom House finds that although 50 percent of the world’s countries today are democratic, 70 percent of those countries are illiberal in the sense that people don’t have free speech or freedom of movement. But also, we’re finding from Freedom House in a study that they published last year that freedom has been on the decline every year for the past seven years.

This line of reasoning can quickly create a vicious cycle: when one state is wary of another state’s intentions, it may begin to act hostilely toward the other state; then, the other state will mistrust the first state the first state, and also act hostilely. Thus, even if both states are originally benign, they can very easily become aggressive because of uncertainty.

Leading realist John Mearsheimer puts it this way in his book, The Tragedy of Great Power Politics (p. 31):

No state can be sure that another state will not use its offensive military capability to attack the first state. This is not to say that states necessarily have hostile intentions. Indeed, all of the states in the system may be reliably benign, but it is impossible to divine with 100 percent certainty.

In Leviathan, Thomas Hobbes presents his theory of the state of mankind in a true state of nature:

In such condition, there is… continual fear, and danger of violent death; and the life of man, solitary, poor, nasty, brutish, and short.

Although Hobbes was describing man’s position in an anarchic system, realists view the state’s position in the anarchic international system similarly. Because there is no truly sovereign supranational organization, states are always in danger of being attacked, and must act defensively (and often violently), just as humans would act if there was no functioning state.

Incidentally, this idea supports the realist approach to international relations. Realism contends, generally, that “State power is the key—indeed, the only—variable of interest, because only through power can States defend themselves and hope to survive”, and, “survival is the principal goal of every State”. Through this lens, states would be expected to prioritize “questions and arguments of power” over “common welfare and justice”.