There is no bubble. The return on investment for a college education may be less than what it once was, but the net present value of a bachelor's degree is still positive. That's an economic argument predicated on the proposition that an education's function is solely to develop human capital, thereby increasing productive capacity of the person and enabling that person to earn more for their services relative to what they would have earned without a degree.

This, of course, ignores another significant component of economic behavior regarding education. Specifically, in addition to it's vocational value, education is a service purchased to meet the human need for self-actualization. When you see a human-interest article in the local news about a 70 year old grandmother who has just completed her bachelor's degree, you are seeing evidence of economic demand for education that has no vocational basis.

I am not saying that the existing trend of the cost of tuition outpacing CPI can continue indefinitely. Clearly it can't. However, it is a mistake to label the present circumstance as a bubble.