射手理論是科幻巨著《三體》第一部第3章：射手和農場主。
描寫男主角 汪淼的日常時提到的，原文說是“科學邊界”組織的學者們進行討論時，經常討論的一個縮寫詞：SF。源自兩個假說，都涉及到宇宙規律的本質。
一個是“射手假說”，另一個是“農場主假說“
射手假說：有一名神槍手，在一個靶子上，每隔10cm打出一個洞。構想這個靶子上生活著一種二維智慧型生物，它們中的科學家在對自己的宇宙進行觀察後，發現了一個偉大的定律：每隔10cm單位，必然會有一個洞。 它們把這個神槍手一時興起的隨意行為，看成自己宇宙中的鐵律。
農場主假說：一個農場裡有一群火雞，農場主每天上午11點來給它們餵食。火雞中的一名科學家觀察這個現象，一直觀察了近一年都沒有出現例外，於是它也發現了自己宇宙中的偉大定律：每天早上11點，就有食物降臨。 它在感恩節早晨向大家宣布了這個定律，但這天早上11點食物沒有降臨，農場主進來把他們都捉去殺了。
農場主理論的原型是羅素的火雞理論。如下。
The turkey found that, on his first morning at the turkey farm, that he was fed at 9 a.m. Being a good inductivist turkey he did not jump to conclusions. He waited until he collected a large number of observations that he was fed at 9 a.m. and made these observations under a wide range of circumstances … Each day he added another observation statement to his list. Finally he was satisfied that he had collected a number of observation statements to inductively infer that “I am always fed at 9 a.m.”. However on the morning of Christmas eve he was not fed but instead had his throat cut.
(The story by Russell is found in Alan Chalmers,What is this thing Called Science, Open University Press, Milton Keynes, 1982, p. 14)
