The advice thread has gotten long and tedious. I think there are some who might be confused as to how a P/E is determined. Being no expert, rather a long-time observer, I'm sure there are others who can explain it better than I. (But that won't deter me from trying.)
My understanding is that the price of a company's share of stock is that which a buyer is willing to pay for $1 worth of dividends in the future; thus, price/earnings. It is that willingness to pay which is crucial to acknowledge, willingness often not based on facts. It is not the company who determines the price of the share of stock as most shares are sold by others owning the shares rather than company owned shares. Thus, movement up or down in the stock market is based largely on people's perceptions of a future event, an event which cannot be forecast to 100% accuracy.
The discussion has been not on the P/E of a particular company, but on the P/E of an index. Discussing whether the P/E of General Motors will go up or down is not what is being discussed in the other thread, but that of a basket of 500 stocks. Evidence is more likely to exist for the movement of a particular stock, but the movement of a basket of stocks is more likely to be influenced by human behavior, and human behavior has evidence in a historical perspective rather than current events.
That historical perspective tells me that people will be looking to make money buying stocks that they perceive as being cheap and it appears there are many who believe stocks are cheap now. Therefore, based on the law of supply and demand, stocks are poised to increase in price.
Elizabeth Richardson