‘Sound message, faulty delivery’: Why good arguments don’t always work

Less could be more when it comes to making a persuasive argument.

The world is more connected than ever before, and unsurprisingly this means we’re having more conversations  — and arguments — in our workplaces, personal lives and on the internet.

There’s a premium on being effective, but there’s often a difference between a good argument and a persuasive one.

As Niro Sivanathan, associate professor of organisational behaviour at the London Business School (LBS), explained in a recent TEDx talk, a sound message isn’t necessarily influential.

“Far too often we see people speak up, but fail to influence others,” Sivanathan said.

“Their message was sound, but their delivery proved faulty.”

Whether it’s convincing your cousin the latest Aquaman movie sucked (hint: it did) or persuading a potential business partner to sign the dotted line on an important contract, a good argument poorly delivered is an opportunity missed.

Sivanathan has spent years undertaking phenomenological analysis of the way the human mind processes information and says weak arguments often err because people often pile on too much evidence.

Sivanathan contrasts diagnostic information, that which is of relevance to a decision being made, with non-diagnostic information, or that which is irrelevant or inconsequential to that same decision.

Research suggests the human mind averages diagnostic and non-diagnostic information presented to it, meaning increasing the quantity of information or evidence presented weakens whatever argument is being made.

Known as the “dilution effect” among behavioural economists, the phenomenon can have a drastic effect on how persuasive an argument is, regardless of how sound the argument itself is.

“In the world of communicating for the purposes of influence, quality trumps quantity,” Sivanathan said.

“By increasing the number of arguments, you do not strengthen your case, but actively weaken it.”

Understanding the dilution effect can improve how persuasive an argument is, but as Sivanathan explains, it has also been used in marketing by companies seeking to obfuscate information. This is similar to the well-known Red Herring fallacy.

In the United States, the Federal Drug Administration (FDA) forces pharmaceutical companies to list the side effects of drugs they advertise on television. Sivanathan uses the example of a sleep drug, which has side effects including heart problems.

While drug companies are required to tell customers about these side effects at the end of their ads, there’s no regulation dictating in what order they present those side effects. So, in a case where a drug may cause itchy feet, pharmaceutical companies list that side effect last.

This, as Sivananthan explains, utilises the dilution effect to lessen the negative risk assessment made by potential customers, even though the actual risk profile is unchanged by the manner in which they are presented in the ad.

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