if all you have is a hammer, everything looks like a nail
from Wiktionary, Creative Commons Attribution/Share-Alike License
- With limited tools, single-minded people apply them inappropriately or indiscriminately
- If a person is familiar with a certain, single subject/has with them a certain, single instrument, they may have a confirmation bias to believe that it is the answer to/involved in everything.
Likely traditional. In this form, perhaps from Abraham Maslow, The Psychology of Science, 1966, page 15 and his earlier book Abraham H. Maslow (1962), Toward a Psychology of Being: (Wiktionary)