Investing in stock in a volatile environment

Should a young person invest hard earned savings in stocks in a volatile environment? The answer can be found here: http://money.cnn.com/2011/11/04/pf/expert/young_investors/index.htm?section=money_topstories&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2Fmoney_topstories+%28Top+Stories%29

I agree with the advice that money for the long term, e.g. for retirement, should be invested in stocks and that money needed for the short term, e.g. to make down payment for a home or other specific purpose, should be invested in a secure asset, such as an insured bank account.