What to think about second-hand information

The theory

A commenter on my last post about how information spreads pointed out the difficulties in deciding what to think about second-hand information: how much should you trust it? This is a very tricky part of the problem of doing good thinking.

There are a few questions that can help you decide how much to trust second-hand information.

• Does this person know what they are talking about firsthand? Do they know about the facts they are talking about because they personally witnessed them or discovered them? The more hops there are between you and the original facts, the more degraded the information will be.
• What is the nature of the information? Some things are harder to fake than others. Anybody can make up a story, even on the spot. A photograph can be easily retouched, but it takes time and effort. Retouching a video takes a lot more effort, and few people can do it.
• Is the information anecdotal or statistical? "Anecdotal" means that somebody is telling you one story about one person, in one place, at one time. "Statistical" means that somebody has collected data from a large number of people or situations, and added up the numbers. If you are interested in a general picture, rather than a single story, statistical information is always more reliable.
• How long ago did the facts happen? The longer it's been since it happened, the more chances that people have forgotten or twisted the facts since then.
• How much of what this person is telling you is about their feelings? The more the person talks about their feelings, the more they are likely to be mixing feelings up with facts, and altering facts in their mind to match their feelings about them.
• Who is this person trying to reach? People always tell things for a reason and with a specific audience in mind. Do you know why this person is telling you this? Does this person have reasons to try to deceive you or whoever they are talking to? Is this person trying to "sell" something? (literally or in the general sense). Is this person likely to want to hide something about this from their audience?
  
• Can you compare the facts this person is giving you with other independent sources? "Independent sources" means that you think it's unlikely that this person has talked with the other source and compared notes. If you can be sure that the sources are independent, this can be a powerful way of finding out the truth, because it's very likely that they're both telling the truth if they both say the same thing. This is why the police are very careful to interrogate suspects separately, and attempt to catch them before they have had a chance to agree on a story. They know that their suspects are usually the kind of people who lie often, but the chances of two liars coming up with exactly the same lie are slim.

If you ask yourself all these questions, you should have a clear idea of how trustworthy is this information.

The practice

Apply these questions to the following statements. Please research and find your own sources.

• Solar and wind power are the best sources of energy for the purpose of reducing carbon emissions.
• Using renewable energy will reduce our dependence on imports from countries that currently have very different interests from ours.
• Using more renewable energy will create more jobs locally.
• Electric cars will substantially reduce demand for oil.
  

What are your conclusions?