被放上桌的那塊石頭（名詞）
同一個畫面換個角度看：不是看那個動作，而是看被擺出來的那樣東西。英文常常讓動詞和它的產物共用一個字形，這裡就是這樣。
noun · C1
Something taken as true without proof, which an argument, a proof, or a piece of scientific work is then built on.
假設；基本前提
核心畫面
One way to hold this word: somebody puts a stone down on the table and says, let us all agree to start from this. Nobody has proved the stone is sound. The request is only that we accept it, so that something can be built on top. The verb is the putting-down; the noun is the stone. Everything else in an argument sits on it, which is why a bad stone brings the whole wall down.
可以想成這樣一個動作：有人把一塊石頭放到桌上，說「我們就從這裡開始吧」。沒有人證明過這塊石頭夠不夠硬。他要的只是大家…更多收起
可以想成這樣一個動作：有人把一塊石頭放到桌上，說「我們就從這裡開始吧」。沒有人證明過這塊石頭夠不夠硬。他要的只是大家先答應，好讓後面的東西蓋得上去。動詞是「放下去」這個動作，名詞就是那塊石頭。整套論證都壓在它上面——所以石頭一鬆，整面牆會跟著垮。From the word’s history
The supplied entry traces both the verb and the noun to Latin postulo, to request, with the noun from postulatum, the thing requested. The asking is still inside the modern word: you do not prove a postulate, you ask people to grant it.
來源說動詞和名詞都出自拉丁文 postulō（要求、請求），名詞來自 postulātum，也就是「被請求的那樣東西」。這層「請求」的意思到今天還在：你不是證明一個 postulate，你是請大家先答應它。
Wiktionary entries for postulate (noun, etymology 1; verb, etymology 2), source_refs kaikki:3f6f69a190036ae4:280353662 and :280378672, supplied in this packet
From the picture
Also in this word
verb · C1
To say that something is probably true or probably happened, and then use it as the starting point of an argument, a proof, or a piece of research, before it has been proved.
假定；提出（假設）