Empirical rejection of mainstream economics' core postulates -on prices, firms' profits and markets structure.

Mainstream economics relies largely on deductive assumptions –not resulting from a systematic gathering of observations. Among them, those assumptions on prices determination by firms, firms’ size relative to market demand, and the prevailing market structure regarding the competition/monopoly axis. The present paper is devoted to presenting the results of confronting these assumptions with the extensive empirical evidence about. As a result it is argued here that these core assumptions cannot actually be sustained; hence, the economics’ standard model built upon them is not a useful theory to explain the workings of market economies, teach economics at class rooms, etc.