It appears that, from the early 1870s, Kronecker was opposed to the use of irrational numbers, upper and lower limits, and the Bolzano - Weierstrass theorem, because of their non-constructive nature.
Ito ay lumilitaw na, mula sa maagang bahagi ng 1870s, Kronecker ay tutol sa paggamit ng mga hindi makatwiran numero, itaas at mas mababang mga limitasyon, at ang Bolzano - Weierstrass teorama, dahil sa kanilang walang-liwanag ng kalikasan.