Defined Benefit Pensions

Meaning that someone gets a known amount of pension after so many years and it doesn't depend upon any kind of investment as far as the pensioner is concerned.

Many pensions used to be that way but corporations soon discovered it was cheaper to do it another way---they got the defined contribution plan, and your pension would depend upon an investment as to how much you might get.

If you happen to work during a particularly bad investment time, your pension could be small. Also, the reverse could be true if things were wonderful in investments.

The real problem in either system is really that they allow people to draw too much pension in too few years! Heck some of us who served in the military from 17 years of age for 20 years could retire on half pay at 37! Full pay at 47. ( full pay not exactly the same as civilian full pays, however.

Fairness would dictate something like the following:
Use both systems and give the pensioner the best one at retirement.
Start the first one at 20 years working but for only one-fourth pay or at least what you invested, if anything.
The second tier of 30 years would pay 60%, and the third tier at 40 years would pay 85%.

There are a lot of other variables, like moving jobs, how much one contributes from salary, etc. but that can be worked out.
Social Security? Wouldn't be right to make more money after you retire than before, so use that for a health plan!