[8] An application of the principle may involve Hume's skepticism, which holds that it is not possible to know the induction hypothesis needed to determine the derivative knowledge that P from what is already known.
[10] While major philosophers of the past (Plato, Aristotle, Augustine, Shopenhauer) endorsed the principle, in the beginning of the 21st century the acceptance of the KK thesis widely varies between the epistemologists.
[2] Timothy Williamson presented a "very influential" attack on the KK principle in 2000 in his book "Knowledge and its Limits".
[13] In response to the critique about the implausibility of the KK thesis, Hintikka stated that it is not an important point because what matters is that the principle is able "to capture a strong sense of knowledge".
[14] Modern formulations of the thesis sometimes include qualifications requiring, for example, "normal conditions for psychological self-knowledge".