It is common to use proper names as adjectives. However, the right use is not always clear to me. To illustrate the question, I'm considering the examples below:

  1. In Newton's theory, objects have mass.
  2. In the Newton theory, objects have mass.
  3. In Newton theory, objects have mass.

According to me, 1. and 2. are correct, above. I am not sure about 3. Are there systematic rules on this matter? Also, there might be additional difficulties when a sentence is started with the proper name:

  1. Newton theory was developed...
  2. The Newton theory was developed...

I am undecided. We could also have an additional adjective as follows:

  1. The preferred Newton assumptions are...
  2. Preferred Newton's assumptions are...

Not to be confused with Newton's preferred assumptions.

[EDIT] What happens when two proper names are combined, with for instance, something like:

  1. In the Lebesgue-Kolmogorov theory
  2. In Lebesgue-Kolmogorov's theory

1 Answer 1


I second Chappo's comment, and would add that regarding 6 & 7, the work Newtonian would be useful.

Definition of Newtonian

1 : of or relating to Sir Isaac Newton or his doctrines

m-w source

  • Great idea for "Newtonian"! I had not thought about it.
    – pluton
    Sep 26, 2018 at 6:07

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