Porn and "Common Sense" Philosophy

Ross Douthat has an absurdist piece up at the Atlantic that appears to take seriously the idea that Pornography is a form of Adultery. The basic argument:

Start with the near-universal assumption that what Spitzer did in his hotel room constituted adultery, and then ponder whether Silda Spitzer would have had cause to feel betrayed if the FBI probe had revealed that her husband had paid merely to watch a prostitute perform sexual acts while he folded himself into a hotel armchair to masturbate. My suspicion is that an awful lot of people would say yes—not because there isn’t some distinction between the two acts, but because the distinction isn’t morally significant enough to prevent both from belonging to the zone, broadly defined, of cheating on your wife.

You can see where I’m going with this. If it’s cheating on your wife to watch while another woman performs sexually in front of you, then why isn’t it cheating to watch while the same sort of spectacle unfolds on your laptop or TV? Isn’t the man who uses hard-core pornography already betraying his wife, whether or not the habit leads to anything worse?

To which Brian Beutler tries to respond in characteristic philosopher fashion, by analyzing things:

sleeping with a prostitute may be like masturbating in front of a prostitute because both involve sexual acts with a prostitute, and masturbating in front of a prostitute may be like masturbating to porn because both involve masturbating, but that doesn't mean sleeping with a prostitute is anything at all like masturbating to porn.

This might be the case, but it doesn't actually matter.

What Douthat does to open up the argument is a thought experiment meant to appeal to our common sense intuitions about adultery, and then makes an argument based upon those intuitions. That's fine, as far as it goes, but this sort of argumentation ought to be reserved for things that we don't already have opinions about. My thoughts on pornography and adultery are already fairly well-formed — as are virtually everyone else's, I'd wager. This is not to say that looking at porn is or isn't adultery (although it isn't), but that a "Common Sense" argument like this is just a non-starter since we already have separate "Common Sense" thoughts on the issue at hand.