This week’s guest blogger is Simon Laham, PhD, a social psychologist and a Research Fellow and Lecturer in Psychological Sciences at the University of Melbourne, Australia. His work focuses on the psychology of morality.

Matthew is playing with his new kitten late one night. He is wearing only his boxer shorts, and the kitten sometimes walks over his genitals. Eventually, this arouses him and he begins to rub his bare genitals along the kitten’s body. The kitten purrs and seems to enjoy the contact.

What do you think about this? Morally right or wrong? Well, if you’re like most, you think that Matthew’s behavior is not only pretty disgusting, but morally condemnable.

But now ask yourself why you think it’s wrong? No one is harmed here, after all; Matthew is having fun and it seems that the kitten isn’t too bothered. What about germs? Well, let’s say that the kitten has just been bathed and there is no chance of Matthew catching something. Still wrong?

When psychologist Jonathan Haidt presented participants in one of his studies with scenarios just like this (depicting harmless, but norm-violating behaviors, such as masturbating with frozen chickens and eating road kill), he found that many people relentlessly insisted that such behaviours were “just wrong,” even though they couldn’t muster any convincing justifications. These participants sat, “morally dumbfounded,” as Haidt put it, asserting simply that “it just feels wrong.”

When prodded, people’s moral foundations tend to wobble a little bit. Although many of us like to think that our moralities are firmly grounded in principles – thou shalt not kill, love thy neighbour as thyself – and that moral judgments spring from the logical application of such principles, it just so happens that many of our moral judgments aren’t driven by the rational, deliberative contemplation of moral rules at all. Rather they are driven by intuitions. We witness an action, experience an intuitive flash of disgust, or anger, for example, and, as a result, deem the action morally wrong. Matthew isn’t violating any lofty moral law with his kitten rubbing, he’s just doing something disgusting, and, thus, wrong.

Just where do these intuitions come from? It’s quite likely that they have an evolutionary basis. Put simply, we feel disgusted or angry about behaviors that somehow compromised the reproductive success of our evolutionary ancestors.

Take incest as an example. Those ancestors of ours who happened to have felt disgust at incest would have been less likely to commit it, and thus more likely to have produced viable offspring, passing on their incest-condemning genes to future generations. Certain moral intuitions conferred reproductive advantages in the past; those are the moral intuitions we feel today.

It’s quite sobering to realise that your moral outlook is shaped not by appeal to higher reason, but by the contingencies of your evolutionary history. Still more sobering, however, are results from other research which suggests that opinions about important moral questions are influenced by a raft of other, thoroughly irrelevant factors.

Consider this: if I had happened to write the Matthew scenario above in chiller font or blackadder ITC font or some other difficult to read font, chances are you would have found it even more morally wrong than you did originally. Some work from my own lab shows that when people have a difficult time processing a stimulus (because, for example, it’s hard to read), they are more likely to think it’s morally wrong than if they have an easy time processing it. The idea here is that “disfluent” processing feels negative, and this negativity seeps into our moral judgments, making us harsher moral critics.

Or consider this question: What entities in the world deserve our moral consideration? Apes? Dogs? Fetuses? This is not a trivial question. Your answers will form the basis of your attitudes towards vegetarianism, abortion, or animal experimentation, among other pressing moral issues. Yet even here we see the subtle influence of moral irrelevancies. When people are asked to generate a list of such morally worthy entities by selecting candidates from a longer list, they end up with fewer candidates than people asked to cross unworthy entities off a longer list. The size of your moral community, in other words, depends on how you happen to be asked to populate it.

The list of subtle shapers of moral judgment goes on: show people a clip from Saturday Night Live and they are more likely to make utilitarian judgments; have them make judgments in a dirty room, littered with used tissues and pizza boxes, and they become harsher moral judges; expose people to “fart spray” and they less likely to endorse marriage between first cousins…

It should give you pause to realize that your judgments of right and wrong – be they about euthanasia, incest, abortion, or kitten masturbation – are subject to a range on non-rational, gut feelings or intuitions rather than under the control deliberative, rational, reasoning processes. The belief that our moral compasses are guided by a set of well thought-out principles that we consciously and painstakingly apply to each new situation is simply inconsistent with the empirical evidence. This belief fails to capture the complexity of moral judgment and it ignores the now well-documented fact that our judgments of right and wrong are driven largely by intuitive and often irrelevant factors that reside largely outside of our awareness.