Will Storr is a man who deals in facts. As a journalist of more than 10 years, undeniable evidence and rational data are his bread and butter.
There are groups of people, however, who deny the irrefutable; who see cold, hard facts as mistruths or simply inconvenient.
Whether they are Holocaust deniers, creationists, or those who believe in UFOs - there are plenty out there whose view of the world defies centuries of scientific evidence.
So why are there intelligent, seemingly rational people like this, who are capable of such unreasonable logic?
The question is the subject of Storr's new book, which explores the 'beliefs of non-believers'. Put simply, he wants to know why 'facts don't work'.
He takes a tour of a Nazi death camp, goes on a UFO-spotting trip, and even a fossil excavation with a renowned creationist, all in the name of investigating outlandish belief systems.
Storr studies not only the thought process behind conspiracy theories, but also the unwavering rationalism of their opponents.
His result, 'The Heretics: Adventures with the Enemies of Science', has been described as hilarious and gripping in equal measure, owing to the characters he meets along the way.
Some of the 'heretics' are harmless oddballs, including a woman who says during a UFO-spotting session: "If a UFO lands, you must wait until it's stopped completely before approaching.
"Only invite the ETs to come closer if it is absolutely safe to do so. If anyone gets zapped, the first-aid kit is in the back of my tent."
On his quest to explore nonsensical logic, he also tours a Nazi death camp with former Holocaust denier David Irving.
Irving proclaims that a gas chamber they visit in Majdanek, Poland, is actually 'a mock-up of a gas chamber'.
Pointing around the room, Irving identifies a door with a handle on the inside, insisting Jews could have got out and that the site did not see any mass murder after all.
There is a door with a handle, but it has no opening mechanism and bolts on the other side - facts which are conveniently ignored by Irving.
Earlier on he meets noted creationist preacher John Mackay, who insists that fossils show no record of evolution and that the 9/11 attacks were God 'punishing' a sinful America.
Storr, 38, explained to Yahoo! News: "This man went to university and is clearly an intelligent person, so how does he come to these ideas?
"He says he is a creationist and can feel God in his body - and the book goes along with that idea.
"Despite all the evidence, no matter how convincing it is, he assumes it cannot be right."
Storr admits that some of the beliefs he came across were more offensive than others, but says 'confirmation bias' plays a large role in how we form our views.
This means that many people subconsciously only choose evidence which supports their views, while selectively rejecting evidence which goes against them.
Confirmation bias, he says, relates to the neurological 'hero maker' that we all share. Storr believes we are all driven by an inner narrative, 'where we are struggling through our days to make better lives for ourselves'.
He adds: "Our brain populates this idea with 'heroes' who support our views and 'villains' in our lives who we demonise - it's a very black and white process. This is the world we live in - the brain is a storyteller."
It is not just the likes of UFO-spotters and creationists who are susceptible to confirmation bias, however.
Storr notes that rationalists can be just as inflexible in their judgments as anyone else.
He attends a conference of 'sceptics', who insist there is 'no evidence for homeopathy'. When he asks the sceptics what scientific literature on homeopathy they've read to support these claims, many admit they haven't read any.
This isn't to say that homeopathy isn't legitimate - merely that many 'rationalists' dismiss it because they don't want to believe it in the first place.
It is the same principle - Storr says we don't base our opinions on evidence, we form opinions first, then seek evidence which backs them up.
Stories, Storr says, are a powerful driving force in shaping our beliefs.
As most of our thought processes are done unconsciously, this kind of natural irrationality sees us create narratives which shape beliefs.
"Stories completely control our understanding of the world," Storr says.
"You rarely read news reports based only on facts, you see stories which owe a lot to fiction - many are written around a narrative.
"It's mainly a book about stories - the ones these people are telling me, and how our whole lives are imbued with stories."
'The Heretics: Adventures With The Enemies Of Science' is available to buy now. More information on the author is available on the Picador website.