In Mises’s account, Catallactics analyzes market phenomena and action based on monetary calculation. It is narrower than Praxeology, the general theory of action, but is not limited to barter, physical products or computing a static equilibrium price.
Buying a book, repair or ticket creates a market relationship even when buyers pursue different ends. Mises does not define the field by whether motives are material, spiritual or selfish. The task is to explain exchange and its consequences, not first approve or classify participants’ wishes. [Mises — Human Action, XIV]
A buyer may prefer the product to the money paid, while the seller prefers the money to the product. A common exchange ratio does not create a common scale of satisfaction. For a particular trade distinguish expected advantage from the actual outcome and establish which alternatives both sides really had. [Mises — Human Action, XV]
Money prices allow offered inputs and a project’s expected revenues to be compared in accounting units. This calculation neither measures personal satisfaction nor guarantees correct forecasts. Catallactics therefore also examines how realized prices affect later offers and plans; a barter-only picture is insufficient. [Mises — Human Action, XIV] [Mises — Human Action, XV]
Mises’s account of a market economy emphasizes private control of production means and cooperation through exchange. A concrete analysis must specify rights, contracting possibilities and action constraints. Studying decentralized decisions means neither assuming a rule-free world nor treating coercion as voluntary consent. [Mises — Human Action, XV]
Hayek shows how price changes can prompt adjustments in resource use without everyone knowing the original cause of scarcity. This is a mechanism for conveying relevant information, not an omniscient report. A particular market requires examination of available offers, opportunities to respond and barriers to information transmission. [Hayek — The Use of Knowledge in Society]
Entrepreneurs compare anticipated revenues with costs and later face actual results. Loss can flag a mistaken plan, but an accounting number alone does not explain every cause. The process requires examining changes in knowledge, conditions and competitors’ responses; profit alone does not establish flawless coordination. [Mises — Human Action, XV] [Hayek — Economics and Knowledge]
Mises uses imaginary constructions to isolate relationships between variables. A model without further change or entrepreneurial uncertainty must not be mistaken for a living market. Hayek also distinguishes compatibility of plans from the process of learning; actual adjustment needs its own explanation. [Mises — Human Action, XIV] [Hayek — Economics and Knowledge]
A valid transaction can establish movement under network rules, not by itself buying motives, a correct price or counterparties’ satisfaction. Catallactics asks about offers, demands, constraints and subsequent changes in plans. Technical data are part of the evidence; without further support they cannot replace an explanation of a specific market. [Mises — Human Action, XIV] [Hayek — The Use of Knowledge in Society]
For the clearest picture, read this entry together with Praxeology, Human Action, Economic Calculation, Knowledge Problem, Entrepreneurship. The reverse links also lead from Praxeology, Subjective Value Theory, Human Action, Economic Calculation.