Anyone over age 50 knows that if they lose their job for any reason, the chances of finding another are much smaller than someone in their 20's (or 30's or 40's). We (yes, I am in this category) just can't compete particularly when handicapped by a physical or mental condition.
The Social Security Regulations recognize this. If your work was more physically and mentally demanding than - say - a job at a call center, or one sorting small objects while seated - and you are unable to do that job and you are overe 50, the Regulations acknowledge the "adverse vocational factor" of age and direct disability for the 50+ person, even when the person would have been able to do other similar work at age 49.
For example, a 49 year old office clerk who has to stand 6 of 8 hours, sit 2 of 8 hours, lift 10 pounds most of the day and 20 pounds up to 1/3rd of a work day gets hurt (back, knees, heart - whatever). The Agency is likely to say that worker can't do his past work, but can do other less demanding work - mostly sitting, lifting a maximum of 5 pounds. Thus the 49 year old person "is not disabled under our [Social Security] rules." However, when that person turns 50, the Social Security rules will direct a finding of disability even if nothing else is different.
Why 50? They had to pick something. It is just true that older people cannot compete in the work force. The rules get even easier for people over age 54.
Congress is considering raising the age to something greater than 50 years. This will make it much harder for those people to establish disability. It makes no sense.
Think of it this way. Many employers offer a retirement package. If a person can no longer work due to injury/illness, that person can receive "disability retirement." That is exactly what the Social Security Act does. Social Security benefits are there for retirement. However, if a worker can't make it to retirement age, they need something to live on. Workers pay into this system for every dollar they receive while working. When they can no longer work, whether it is because of age or disability they should be able to get something back.
If you are reading this, it is because you need help or are concerned about someone you care about who needs help. Now you know what the Social Security Act is supposed to do. If you want it to continue, you're going to have to contact your Congressman or Senator because wealthy people with private retirement/disability insurance are trying to take it away. Find your representative here: http://www.house.gov/representatives/find/