Theoretical Economics and the Second-Order Economic Theory. What is it?

We consider economic agents, agent’s variables, agent’s trades and deals with other agents and agent’s expectations as ground for theoretical description of economic and financial processes. Macroeconomic and financial variables are composed by agent’s variables. In turn, sums of agent’s trade values or volumes determine evolution of agent’s variables. In conclusion, agent’s expectations govern agent’s trade decisions. We consider that trinity - agent’s variables, trades and expectations as simple bricks for theoretical description of economics. We note models that describe variables determined by sums of market trades during certain time interval Δ as the first-order economic theories. Most current economic models belong to the first-order economic theories. However, we show that these models are insufficient for adequate economic description. Trade decisions substantially depend on market price forecasting. We show that reasonable predictions of market price volatility equal descriptions of sums of squares of trade values and volumes during Δ. We call modeling variables composed by sums of squares of market trades as the second-order economic theories. If forecast of price probability uses 3-d price statistical moment and price skewness then it equals description of sums of 3-d power of market trades – the third-order economic theory. Exact prediction of market price probability equals description of sums of n-th power of market trades for all n. That limits accuracy of price probability forecasting and confines forecast validity of economic theories.