Usually I like Zach Weinersmith’s SMBC (Saturday Morning Breakfast Cereal) series, but this one is off the mark:
Well, of course feeling or receiving love and getting kicked in the cojones are subjective sensations, and we don’t yet know exactly how the nerve impulses become perceptions. But we do know two things. First, love and pain have emotional connotations, and when we think about them, they don’t seem like chemical reactions. And love, at least—albeit chemical—is one of the things that makes life worth living. Pain, however, does not, though it serves an immensely adaptive function: alerting us to damage to our bodies.
But I doubt that Weinersmith is just touting the emotional value of love here; rather, he seems to be dissing the very notion that love and pain are chemical reactions. But they are, and we have good evidence for that. You can affect the affections of people and animals by injecting them with chemicals.
Pain, too, is a chemical reaction, or at least has something to do with nerve transmission and is therefore based on molecules. We know this for several reasons. One is the existence of Congenital insensitivity to pain with anhidrosis (CIPA), a genetic disease that simply removes the ability to sense pain (as well as heat or cold) from its unfortunate victims. And they’re “victims” because, heedless of damage to their bodies, they get burned, infected, break bones, and continually hurt themselves without knowing that they’ve done it, and without seeking medical care. If you’re a CIPA sufferer and put your hand on a hot stove, you won’t remove it. The consequences are clear. And so are the implications: if a mutation in the DNA can remove the sensation of pain, and undoing that mutation can presumably bring back the sensation of pain, then pain must be a physiochemical phenomenon.
We know the same thing from local anesthetics, like the novocaine you get at the dentist’s. You’re conscious but don’t feel pain in the area where the chemical is injected. It clearly does something to the nerves or their transmissions that eliminates the subjective sensation of pain. The sensation thus has a neurological/chemical basis.
Unless Weinersmith sees “believing in love” as “finding value in love”, then the cartoon is profoundly antiscientific. But even if he isn’t, the existence of anesthetics and diseases like CIPA tell us that, at bottom, subjective sensation has a materialistic and physical basis. We all know that, but many religionists reject it.