Spock often provided calculations to Captain Kirk
In Star Trek: The Original Series, Captain Kirk often relied on Mr. Spock for his calculations and even his speculations to get the Enterprise out of jams and to save planets. Kirk and Spock worked together liked a well-oiled machine, even when Kirk didn’t always listen to the advice of his second in command.
According to Julia Galef, the author of The Scout Mindset: Why Some People See Things Clearly and Others Don’t and co-founder of the Center for Applied Rationality, it was good that Kirk didn’t listen as Spock was wrong 83% of the time.
According to The Sun which first reported Galef’s findings, the noted skeptic said the Vulcan was wrong a lot of the time. In her quest to determine how often he was wrong, she plotted the times when he was right and the times when he was wrong on a graph. Her findings indicated that events Spock described as impossible happened 83% of the time.
Galef said she faulted him for making “these very confident-sounding predictions about what is going to happen. He will say things like, ‘Captain, there is a 97 per cent chance that we won’t survive’ or ‘The odds of finding survivors are 44 to one’.”
The author also claims Spock is irrational
But the author didn’t just question Spock’s calculations, she also questioned his rationality in an essay she wrote for Big Think called “Debunking Straw Vulcan Rationality.”
"“Spock tends to assume that other people will make decisions rationally and that’s one of the reasons that he ends up getting into trouble, because of course people don’t behave rationally. The human brain is not wired to be rational.”"
So because he knows humans are not rational, he should not expect them to make rational decisions. The fact that he does, according to Galef, makes him irritational.
I would like to point out, as we all know, that Spock was a fictional character, and not one fan has relied upon his ability to accurately calculate whether or not a planet would survive a supernova or anything else for that matter. We can enjoy a series, a movie, and a character without questioning whether or not that character is imparting 100% accurate information, especially in a time period that doesn’t yet exist. And, if we’re going to get technical about this, Spock wasn’t wrong about the calculations; the writers were. Still, that doesn’t make us enjoy the series or the character any less.