Descartes versus Spinoza
This argument about whether belief is automatic when we are first exposed to an idea or whether belief is a separate process that follows understanding has been going on for at least 400 years. The French philosopher, mathematician and physicist René Descartes (below, right) argued that understanding and believing are two separate processes. First people take in some information by paying attention to it, then they decide what to do with that information, which includes believing or disbelieving it.
Descartes' view is intuitively attractive and seems to accord with the way our minds work, or at least the way we would like our minds to work.
The Dutch philosopher Baruch Spinoza (above left), a contemporary of Descartes, took a quite different view. He thought that the very act of understanding information was believing it. We may, he thought, be able to change our minds afterwards, say when we come across evidence to the contrary, but until that time we believe everything.
Spinoza's approach is unappealing because it suggests we have to waste our energy rooting out falsities that other people have randomly sprayed in our direction, whether by word of mouth, TV, the internet or any other medium of communication.
So who was right, Spinoza or Descartes?
Daniel Gilbert and colleagues put these two theories head-to-head in a series of experiments to test whether understanding and belief operate together or whether belief (or disbelief) comes later (Gilbert et al., 1993).
In their classic social psychology experiment seventy-one participants read statements about two robberies then gave the robber a jail sentence. Some of the statements were designed to make the crime seem worse, for example the robber had a gun, and others to make it look less serious, for example the robber had starving children to feed.
The twist was that only some of the statements were true, while others were false. Participants were told that all the statements that were true would be displayed in green type, while the false statement would be in red. Here's the clever bit: half the participants where purposefully distracted while they were reading the false statements while the other half weren't.
In theory if Spinoza was correct then those who were distracted while reading the false statements wouldn't have time to process the additional fact that the statement was written in red and therefore not true, and consequently would be influenced by it in the jail term they gave to the criminal. On the other hand if Descartes was right then the distraction would make no difference as participants wouldn't have time to believe or not believe the false statements so they wouldn't make any difference to the jail term.
And the winner is...
The results showed that when the false statements made the crime seem much worse rather than less serious, the participants who were interrupted gave the criminals almost twice as long in jail, up from about 6 years to around 11 years.
By contrast the group in which participants hadn't been interrupted managed to ignore the false statements. Consequently there was no significant difference between jail terms depending on whether false statements made the crime seem worse or less serious.
This meant that only when given time to think about it did people behave as though the false statements were actually false. On the other hand, without time for reflection, people simply believed what they read.
Gilbert and colleagues carried out further experiments to successfully counter some alternative explanations of their results. These confirmed their previous findings and led them to the rather disquieting conclusion that Descartes was in error and Spinoza was right.
Believing is not a two-stage process involving first understanding then believing. Instead understanding is believing,
a fraction of a second after reading it, you believe it until some other critical faculty kicks in to change your mind. We really do want to believe, just like Agent Mulder.
Not only that, but their conclusions, and those of Spinoza, also explain other behaviours that people regularly display:
* Correspondence bias: this is people's assumption that others' behaviour reflects their personality, when really it reflects the situation.
* Truthfulness bias: people tend to assume that others are telling the truth, even when they are lying.
* The persuasion effect: when people are distracted it increases the persuasiveness of a message.
* Denial-innuendo effect: people tend to positively believe in things that are being categorically denied.
* Hypothesis testing bias: when testing a theory, instead of trying to prove it wrong people tend to look for information that confirms it.
This, of course, isn't very effective hypothesis testing!
When looked at in light of Spinoza's claim that understanding is believing, these biases and effects could result from our tendency to believe first and ask questions later. Take the correspondence bias: when meeting someone who is nervous we may assume they are a nervous person because this is the most obvious inference to make. It only occurs to us later that they might have been worried because they were waiting for important test results.
If all this is making your feel rather uncomfortable then you're not alone. Gilbert and colleagues concede that our credulous mentality seems like bad news. It may even be an argument for limiting freedom of speech. After all, if people automatically believe everything they see and hear, we have to be very careful about what people see and hear.