In the wake of Google Inc.'s (NASDAQ:GOOG) earnings announcement last week, all the analysts who follow GOOG (which opened at $467 this morning) have tweaked their speadsheets and come up with revised, 12-month price targets. According to Henry Blodget, Slate's star analyst-turned-columnist, these targets range from $415 to $650, and none of them is worth a grain of salt.

Blodget has a piece in Slate today about the myriad problems with price targets. Blodget has been highly critical of the securities industry since he was banned for life, and you can see where he's coming from. After all, he knows how the sausage is made, and also how suspect price targets are because of their inherent paradox. Any investment professional will tell you that past performance is no guarantee of future results, but the metrics used to predict a price target (or future results) are all based on past performance. And since each metric is not much more than an educated guess, a price target is not much more than a composite guess based on guesswork. It's like a photocopy of a photocopy -- after a while, you start to lose resolution.

If you want to buy into GOOG, do it because it's a juggernaut, a core holding for anyone who wants a long-term investment in the future of the internet. Not because someone thinks it will be at a certain price at a certain time. Especially since, given GOOG's volatility over the past year, odds are that $650 price target will be revised many times before 12 months is over.