She had a choice - either go against surrounding her "senior management team desperate to protect their own reputations and that of the Royal Mail" or blame those lowly sub-postmasters. It isn't about "honestly believing", it is what people to side with - your own who is just like you or the very different others.

>They told her that there simply couldn’t be problems with the IT system on the scale that was being suggested

and thus they provided her with plausible deniability. Like that Enron CEO who supposedly didn't know the financial details and relied on what is told by his CFO/etc.

The whole article sounds like a whitewash of senior management responsibility by blaming it on the lower ranks who reports "rosy picture". No wonder that the author seems to be a successful consultant - i can see how his expert opinion may be helpful for such a whitewashing by establishing the existence of the "thermocline of truth" in the specific situations what he gets brought into and thus is liked by the upper management.

As an extra example of "thermocline of truth" - that EBay CEO discussed again just yesterday who supposedly didn't know how his security chief with the gang were criminally harassing the blogger to carry out the CEO's order to “take her down”.

I think approaches like RICO or SOX or plain old army principle that the CO is responsible for whatever happens under his command are the examples of the tools to pierce the "thermoclines of truth".

The article doesn’t blame the underlings that report a “rosy picture”, but rather blames the culture that heavily incentivizes reporting a rosy picture regardless of the facts on the ground, and punished everything else. And the people with the most power over this culture are the ones at the top, making them the most culpable for the thermocline.

setting aside how top managers weaponize anything into "blame others and excuse themselves", the blame is more clear in the original blog post linked in the article https://brucefwebster.com/2008/04/15/the-wetware-crisis-the-...

If you're "siding", you aren't "honestly believing". You're choosing what you want to hear and believe, rather than choosing truth.

IANAAccountant, but I have run systems that fed into G/L systems. If the G/L were set up halfway correctly, everyone in the executive suite would have known that Horizon was producing bad data. Most transactions at a post office would either have had effects on inventory (buying stamps or stationery) or on liabilities (if a customer paid to send a package, someone would have to actually deliver that package). "Duplicate" transactions would only escape notice for services provided immediately without reducing inventory, like a haircut. I doubt many people are getting their hair cut at the post office.

This whole episode calls to mind the authoritarian reaction to "impossible" hacks of the various chip'n'pin schemes rolled out in UK over the years. The credit cards were assumed to be perfect, so account holders were held responsible when they got hacked. [0] In general, individuals in conflict with giant organizations should have access to appeals outside those organizations.

[0] https://www.lightbluetouchpaper.org/2012/09/10/chip-and-skim...

> How could anyone honestly believe that mass collusion amongst a distributed and isolated group of people

This is pure speculation and I don't want to sound like I'm supporting the Post Office and Fujitsu's behaviour, which was despicable.

I wondered if their previous systems were, internally, considered to be very flaky. You then get a new shiny system with a very different set of results and instead of the response being "why is the old system and new system disagreeing so badly" you get the response "hey, this is great, the new system has revealed wrong doing the old system was not able to".

As I say it's a guess but I just wondered.

Occam's razor, you mean; Hanlon's razor is the one about not attributing to making what could be explained by stupidity