generalize from

generalize from (something)

To reach a conclusion about someone or something despite a lack of supporting evidence or information. I know you don't like Rosemary, but I think you're just generalizing from your limited interactions with her—I've always known her to be a very sweet woman.
See also: generalize
Farlex Dictionary of Idioms.

generalize from something

to assume a general pattern in something from specific observances of something. You can hardly generalize from only two instances. You can't generalize anything from the testimony of a single witness!
See also: generalize
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • generalize from (something)
  • come to a conclusion
  • come to a/the conclusion
  • wishcast
  • wishcasting
  • speculate
  • speculate about
  • speculate about (someone or something)
  • speculate in
  • speculate on
References in periodicals archive
If the writer had argued that he could generalize from his study of these two elite dynasties of rice planters to rice planters in general in the low country during the nineteenth century, we might be able to take his conclusions more seriously.
Them Dark Days: Slavery in the American Rice Swamps
First, responding is assumed to generalize from the sample and comparison stimuli in the reinforcement histories of Table 1 to the unfamiliar sample and comparison stimuli arranged in studies of stimulus equivalence.
A traditional account of stimulus equivalence