Overwhelming evidence can weaken credibility of case

Sydney, Jan 13 (IANS) Overwhelming evidence without a dissenting opinion can weaken the credibility of a case, or point to a failure of the system, a new study reveals.

A team of researchers took the example of an ancient Jewish law that said a suspect could not be convicted of a capital crime if all judges unanimously handed down a guilty verdict.

“It might sound counterintuitive to say that a unanimous verdict could be wrong, but this ancient law indicated that the system may be in error if there was complete agreement among the judiciary,” said Derek Abbott, from the University of Adelaide, Australia.

The team put three different scenarios to the test based on mathematical probability: The use of witnesses to confirm the identity of a criminal suspect; the accurate identification of an archaeological find; and the reliability of a cryptographic system.

They found in each case that there was a point at which “too much of a good thing” actually weakened confidence in the result.

“In our first example, we imagine there are 13 witnesses who all confidently identify a criminal suspect after seeing the suspect briefly,” Abbott said.

But, Abbott added that getting a large group of unanimous witnesses in these circumstances is unlikely, according to the laws of probability.

“It’s more likely the system itself is unreliable,” he said.

Abbott further pointed out that in the scenario, the probability that a suspect is guilty is strong after three positive identifications by witnesses.

“But our tests showed that the more positive confirmations you have beyond those three, the more it erodes our confidence that this is the right person being identified,” he explained.

“The ancient Jewish legal practice referred to in our work indicates a surprising level of intuitive sophistication for the time, when such statistical tools would not have been at their disposal. They knew that it was rare for everyone to agree,” Abbott said.

The paper will be published in the forthcoming issue of Proceedings of the Royal Society.

Leave a Reply

Please enter your comment!

The opinions, views, and thoughts expressed by the readers and those providing comments are theirs alone and do not reflect the opinions of www.mangalorean.com or any employee thereof. www.mangalorean.com is not responsible for the accuracy of any of the information supplied by the readers. Responsibility for the content of comments belongs to the commenter alone.  

We request the readers to refrain from posting defamatory, inflammatory comments and not indulge in personal attacks. However, it is obligatory on the part of www.mangalorean.com to provide the IP address and other details of senders of such comments to the concerned authorities upon their request.

Hence we request all our readers to help us to delete comments that do not follow these guidelines by informing us at  info@mangalorean.com. Lets work together to keep the comments clean and worthful, thereby make a difference in the community.

Please enter your name here