What is the meaning of 'proof upon proof' in the sentence: "Piaget and his many collaborators had seemingly collected proof upon proof of young children’s inability to understand arithmetic."

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    @Mari-LouA - This question doesn't mention 'evidence', nor does it request the meaning of 'proof' as a word on its own so I'm not sure how it is related to the other question. Commented Oct 19, 2015 at 12:10
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    @chaslyfromUK The answers describe the meaning of proof very well, I think. Do you know if the OP understands the term proof, I don't.
    – Mari-Lou A
    Commented Oct 19, 2015 at 12:17
  • It's proofs all the way down...
    – anemone
    Commented Oct 19, 2015 at 12:28
  • @mathallica, if you return: Please be explicit in questions about what it is that you do not understand (for example, here it appears to be upon, rather than proof), and please show evidence of what you have looked up, in order that others don't repeat a fruitless search.
    – Andrew Leach
    Commented Oct 19, 2015 at 13:02

1 Answer 1


"Proof upon proof" means a large amount of evidence (or proofs.)

layer upon layer/mile upon mile: used to emphasize that there are a lot of layers, miles etc.

Example: mile upon mile of golden sand

(Longman, the entry on "upon")


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