On page 118 of Thinking Like a Lawyer by Frederick Schauer, I found this passage:

If the purchase for changing a rule[,] is a perception of what the optimal result would be in the absence of the rule, and if every case in which the rule generates a suboptimal result is understood to be one in which the rule should be changed so that it no longer produces these suboptimal results, then it appears as if the rules are not operating as rules at all and that all of the work is being done by the rule-free determination of the optimal result.

I see that purchase is being used as a noun here, yet what does it mean?

None of these three Oxford Dictionaries definitions under noun seem to apply to this context.

I’d guess its meaning here as “reason, rationale”, but I don’t know.

  • In that context I think 'purchase for' of being used in the sense of 'advantage of'.
    – Philip
    Commented Jul 21, 2014 at 9:58
  • Three noun senses is nothing. The OED has 16 main senses for the noun purchase, with numerous subsenses adding up to 25 attested historical senses. I very strongly suggest that you acquire access to the OED.
    – tchrist
    Commented Jul 21, 2014 at 13:26
  • What does "some book" mean? Is there some secret?
    – fdb
    Commented Jul 21, 2014 at 13:51

1 Answer 1


It's meaning 2, 'firm contact or grip', but in a metaphorical sense (i.e. not literal, since there is no physical contact) coloured by the original meaning of the verb 'seek to obtain'. Literal usage, as shown by the examples, typically conveys a sense that the contact is firm only through significant effort (that is, it is something that was 'sought to be obtained').

The author is implying that the optimal result might seem a good reason to change the rule, but that the person seeking to change the rule set out with that as their object and only subsequently identified the optimal result as a post hoc justification - indeed, a 'rationale'.

  • Thanks. Would you please explain and enlarge on this 'metaphorical sense' here? I don't understand how purchase applies here, but thanks to you, I do understand what the quote says.
    – user50720
    Commented Oct 27, 2014 at 6:56
  • Will you please to respond in your answer, and not as a comment?
    – user50720
    Commented Oct 27, 2014 at 6:57

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