• Leonard Peikoff
    “X is possible” means: in the present context of knowledge, there is some, but not much, evidence in favor of X and nothing known that contradicts X.
  • Leonard Peikoff
    When you say “maybe,” you are saying there is at least some evidence, some reason to suspect X. This is a claim that must be justified. There are many fantasies that are outrightly impossible, because they contradict already known facts. And there are other fantasies that are mere arbitrary inventions; even if you cannot specify facts which contradict these inventions, you have absolutely no basis to hypothesize them.
  • The Objectivist Forum

    It is possible, the skeptic argument declares, for man to be in error; therefore, it is possible that every individual is in error on every question. This argument is a non sequitur; it is an equivocation on the term “possible.”

    What is possible to a species under some circumstances, is not necessarily possible to every individual member of that species under every set of circumstances. Thus, it is possible for a human being to run the mile in less than four minutes; and it is possible for a human being to be pregnant. I cannot, however, go over to a crippled gentleman in his wheelchair and say: “Perhaps you’ll give birth to a son next week, after you’ve run the mile to the hospital in 3.9 minutes — after all, you’re human, and it is possible for human beings to do these things.”

    The same principle applies to the possibility of error.