The concept of need is often looked upon rather unfavorably by economists, in contrast with the concept of demand. Both, however, have their own strengths and weaknesses. The need concept is criticized as being too mechanical, as denying the autonomy and individuality of the human person, and as implying that the human being is a machine which "needs" fuel in the shape of food, engine dope in the shape of medicine, and spare parts provided by the surgeon.

Political conflict rests to a very large extent on a universal ignorance of consequences, as the people who are benefited by any particular act or policy are rarely those who struggled for it, and the people who are injured are rarely those who opposed it.

Even personal tastes are learned, in the matrix of a culture or a subculture in which we grow up, by very much the same kind of process by which we learn our common values. Purely personal tastes, indeed, can only survive in a culture which tolerates them, that is, which has a common value that private tastes of certain kinds should be allowed.

As long as man was small in numbers and limited in technology, he could realistically regard the earth as an infinite reservoir, an infinite source of inputs and an infinite cesspool for outputs. Today we can no longer make this assumption. Earth has become a space ship, not only in our imagination but also in the hard realities of the social, biological, and physical system in which man is enmeshed.

The economy of the future might be called the "spaceman economy," in which the earth has become a single spaceship, without unlimited reservoirs of anything.

Reality, in its quantitative aspect, must be considered as a system of populations... The general study of the equilibria and dynamics of populations seems to have no name; but as it has probably reached its highest development in the biological study known as 'ecology,' this name may well be given to it.

Economists are like computers. They need to have facts punched into them.