Henry Blodget’s Business Insider runs a column today from a prominent Silicon Valley venture capitalist arguing that there’s no new Web bubble. Blodget says on Twitter: “Anyone who disagrees, please refute logic. Don’t just huff and snort.”

Well, okay.

Here’s what the VC, Ben Horowitz, says is his reason No. 1 why there’s no new tech bubble:

In the great bubble of 1998-2000, the boom in public valuations mirrored the boom in private valuations. Similarly, in recent high profile private financing rounds for private technology companies with valuations over $1B, the valuation multiples were at or below corresponding multiples for publicly traded companies such as Google.

Alas, we’re not given any numbers on these new companies’ low, low valuations, we just have to take his word for it. And I don’t.

Google has a price-to-earnings ratio of 22 right now. Facebook, for instance, has a P/E of 125 based on its latest top valuation of $75 billion and BI’s own reporting of 2010 net income.

Google has a price-to-sales ratio of 6. Facebook has a price-to-sales ratio of 38. I can’t calculate Facebook’s price-to-earnings-growth ratio (i can’t find apples-to-apples numbers on net income and/or ebitda), but that one at least is probably in the ballpark of Google’s or lower. And growth is obviously a critical factor here, but it’s just one of the three metrics Horowitz points out.

But, also, Horowitz says this:

If publicly traded technology companies are not at bubble-like prices, then private technology valuations aren’t either because they are roughly equivalent.

Then he goes and makes a chart with four stocks of companies that survived the tech crash a decade ago. The fourth? Amazon, whose P/E ratio is at a sky-high 66. Another, Akamai Technologies, has a P/E of 40. But those aren’t “bubble-like prices”?

Again, that’s in his No. 1 argument why there’s no Web 2.0 bubble.

There’s another fallacy here: That valuations have to approach the jaw-droppingly stupid levels of 1999 and 2000 for there to be a bubble. That’s just not the case. No one I’ve seen has said that the current bubble is anywhere near as nutty as that one. This time around there are real earnings and real companies.

But March 24, 2011, is just a snapshot in time and the trend is all up—and fast. Already, Groupon has gone from turning down a $6 billion offer from Google to talk of a new $25 billion valuation.

That happened in the last three months.

And it’s the press’s job—as it would have been in 1998 with the tech bubble, or 2004 with the housing bubble—to be very, very skeptical of these things before they get too out of hand.

(UPDATE: I updated the headline to clarify what I meant. It originally said “Better to Be Skeptical Than Sanguine About New Tech Bubble.” Thanks to Blodget for pointing out that that was unclear.)

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Ryan Chittum is a former Wall Street Journal reporter, and deputy editor of The Audit, CJR's business section. If you see notable business journalism, give him a heads-up at rc2538@columbia.edu. Follow him on Twitter at @ryanchittum.