Economists have often been characterized as a dry, calculating bunch, focusing on the allocation of scarce resources with carefully drawn supply and demand curves. The reason for this is that economics has, in Neoclassical theory and particularly within the writings of Lionel Robbins, emphasized choices and competition under conditions of scarcity. Mainstream economic theory, rooted in Neoclassical thought, has continued in this vein, with a focus on market efficiency as the rule. So, why do I have a problem with it?
Mainstream theory embodies decades of debate and rigorous application, but its focus on choice under scarcity has centered the study of economics on products, not people. The assumption that people are there to either consume or produce products moves away from any requirements for basic human well-being, as emphasized by Amartya Sen in his own criticism of Neoclassical economics, supposes that consumers and producers always want to buy or sell more goods, and fails to focus on aspects of nature (such as forests or coral reefs) as more than resources, such as entities with a right to exist without subjugation to the human race.
These assumptions are flawed and not universally held.