Captain Steve Thrust saw it first.

"Look out! A hostile alien robot armed with a disintegrator ray!"

Brains wobbled a little but remained calm. An alien sun gleamed on the polished hull of the spaceship. In the distance the silhouette of a mechanical alien could be seen advancing towards them steadily.

"I - I think there's something about this in the Starfleet Manual," Brains ventured. He pulled the little electronic book from a pocket in his utility belt and flipped it open. It responded to his eye movements, indexes and submenus flashing across the screen until the image stabilised. 

"Ah! Here it is: 'Hostile alien robots: use Epimenides' paradox. Say, "All Earthlings are consistent liars."'"

"How does that help us?" Steve Thrust was the kind of man for whom a blast with a ray gun from mid-air while executing a kung-fu move was better than thinking.

Brains continued: "Uh, quoting the manual, 'Then the robot will say, "If you are a consistent liar, then you must be lying now, therefore it is a lie that you are a consistent liar, so you must be telling the truth at least sometimes. If you are telling the truth now then it must be true that you are a consistent liar, therefore you must be lying now..." and so on. This will cause them to say "does not compute" at higher and higher pitch while their eyes roll about and steam comes out of their ears. During this time they will not be able to use their disintegrator rays. Then their heads will blow off.'"

"Good thinking Brains!" Thrust's jaw set in a steely heroic grin as the robot advanced within a few yards.

"Let nothing stand in my path! Resistance is feudal!" it said in a tinny voice with a distinct American accent.

Thrust leaned nonchalantly on the side of the spaceship and drawled, "All Earthlings are consistent liars."

The robot hesitated, then: "Hah! That - old - thing! It's just words. I work to uninterpreted strings, and this output only appears to have meaning for you, but to me, it has no meaning. So I shall now deliver you to Fang the Frightful!"

Brains frowned. "Uh - not logical, Captain," he said.

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