In Cournot competition, firms decide on the quantity of output to produce independently and simultaneously. What is the primary assumption about how these firms behave regarding their competitors' output?

In Cournot competition, firms assume that their competitors' output levels will remain constant when they decide how much to produce. This means each firm makes its production choice based on the belief that the other firms will not change their quantities in response. For example, if Firm A thinks Firm B will produce 100 units, Firm A will choose its output to maximize its profits based on that assumption. This leads to a situation where each firm's decision influences the market price, but they are all acting independently. The key idea is that firms are interdependent, yet they make their decisions without knowing how much the others will ultimately produce.