After Grevious died, they went to check if Palpatine would give up his emergency powers.
When Anakin told them Palpatine was a Sith, they should’ve just continue with the original plan. See what Palpatine would do and take time to gather evidence and more Jedi.
But they just went crazy like a teenager.
That was just dumb.
Ah yes, the folly of democracy. Or so-called....
shareIn the end? I'd argue that they were stupid the entire way through. Every time something dire came up-- a Sith showing up when they were all supposed to be gone, a clone army being ordered a decade in advance of a seemingly recent and spontaneous decision to form an army, Count Dooku leaving the Jedi, the clone planet disappearing from the library, and so much more-- Yoda and the rest acknowledged it, then seemed to immediately forget about it. They never followed up on any of it or investigated any of it. By the final film, when Palpatine may as well be wearing a t-shirt that says SITH across the front, they seem utterly unaware that he's evil, and only when it's too late do they react.
It's also worth mentioning that these magical space warriors, who we've seen single-handedly defeat armies, are easily disposed of by Stormtroopers, who manage to simultaneously kill 15,000 Jedi once Order 66 is given. Jedi, who can sense across a universe when something is amiss, are caught unawares, and fail to turn around or power up a light saber in self-defense, and are moved down with ease by the most inaccurate shooters in history.
Dumb doesn't even begin to describe how the Jedit behave throughout the prequels.