Don Boudreaux at Cafe Hayek has recently had some excellent posts about what belongs in a well-taught introductory economics course. Calculus is not a prerequisite for understanding these concepts, nor is even much more than basic arithmetic and algebra (for the examples, not the concepts).
Note well that these ten points are different from the ten main points put forth by Greg Mankiw in his intro text.
And yet if I tried to argue that these points were the most important to emphasize in an intro course, I'd be hooted down by most economists who seem to think the most important thing to do in an intro course is to prepare students for advanced courses.
I disagree with that approach for the very simple reason that most students who take an intro course do not go on to take advanced courses.
Here is Professor Boudreaux's list:
[A] well-taught principles course ... is one that teaches, and teaches well, at least ten vital foundational lessons:
(1) the world is full of both desirable and undesirable unintended consequences – consequences that are largely invisible but that even a course in ‘mere’ principles of economics gives us great vision that enables us to “see,”
(2) intentions are not results;
(3) our world is unavoidably one of trade-offs and not “solutions,”
(4) market-determined prices
(4a) are not arbitrary,
(4b) connect millions of strangers to each other in productive ways that almost none of these strangers are aware of, and
(4c) cannot, save under the rarest of unrealistic circumstances, be controlled by government without causing consequences quite the opposite of those that are ostensibly desired,
(5) productive and sustainable complex economic order emerges without design or intention,
(6) individuals respond to incentives,
(7) individuals, and not collectives, choose and act,
(8) wealth is not fixed in amount (and it is not money),
(9) government officials are no smarter or better-motivated than are people operating in the private sector, and
(10) the economy is inconceivably more complex than someone with a poor understanding of economics realizes – so complex that the promises of social engineers are revealed to be fantastic delusions.
A good principles-of-economics course teaches us to appreciate the marvels of the spontaneous market order and, in doing so, teaches humility. Sadly, far too many advanced courses in economics teach the opposite: by their whiteboard rendering of economies as GDP-producing machines, such “advanced” courses instill the mistaken notion that economies are far simpler than they really are. It would be much closer to the truth to say that most of what you learn in Econ 800 is wrong, for in too many cases it dilutes or destroys the truths you learned in a good Econ 101 course.