The Difference in How the Public and Scientists Use "Theory"

The formal scientific definition of theory is quite different from the everyday meaning of the word. It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence. Many scientific theories are so well established that no new evidence is likely to alter them substantially. For example, no new evidence will demonstrate that the Earth does not orbit around the sun (heliocentric theory), or that living things are not made of cells (cell theory), th...

 AI Fails Because it Uses the Wrong Kinds of Computers

My own opinion is that AI has failed to fulfill its promise because we are using the wrong kind of computers. We are using digital computers, and the human brain is probably analog rather than digital. So my guess is that AI will succeed only after we move from digital to analog computing. This is a tough intellectual problem that cannot be solved just by spending a lot of money.

 Nothing is Known by Guess

Nothing is known in our profession by guess; and I do not believe, that from the first dawn of medical science to the present moment, a single correct idea has ever emanated from conjecture: it is right therefore, that those who are studying their profession should be aware that there is no short road to knowledge; and that observation on the diseased living, examination of the dead, and experiments upon living animals, are the only sources of true knowledge; and that inductions from these ar...