I've been interested in philosophical skepticism lately as I've just recently learned about the close relationship between certain schools of ancient skepticism and fallibilism, which I'm told is the most common epistemology of modern science. I've also learned about one particular philosopher among the ancient skeptics, Carneades, who originated the modern concept of probability. According to, for instance, The Internet Encyclopedia of Philosophy Carneades made use of the concept of probability, or in his tongue to pithanon, as the answer to the common response to skeptics that it is simply impractical to live while denying the existence of knowledge. While neither reason, ideas, nor perception can form the basis of knowledge, they all grant us probabilities that we can use to investigate our other impressions of reason or the senses, at least enough to get along with our practical affairs. Am I paraphrasing his philosophy wrong?

So while I used to see philosophical skepticism as entirely different than scientific skepticism, or our modern scientific worldview in general, now I wonder if they are perhaps much more alike than I realized. Maybe it is simply that the concept of "knowledge" has changed over the centuries. For instance, whereas before maybe knowledge was identical with certainty and absolute truth, and now days our concept of knowledge is so infused with fallibilism and pragmatism, that in the ancient context we would find ourselves far more at home in the skeptic school than in any of the others.

Basically, from the position of modern science, were the ancient skeptics right all along? Would it make sense to begin our epistemology of science with them?

  • Makes sense as any new theory that casts doubt on existing knowledge is usually considered and tested and if it holds up existing models and theories revised or accepted as approximations.
    – Andy Boura
    Aug 3, 2014 at 9:42

1 Answer 1


There are indeed affinities between ancient skepticism and modern empiricism. The idea that all knowledge is grounded in observation (rather than pure intuition or rationality) casts doubt on the possibility to know anything about reality beyond phenomena, hence Hume's skepticism on the reality of causation or of laws of nature, for example.

Perhaps an important difference lies in the scope of the skepticism involved. Ancient skepticism seems broader than empiricism, in that modern empiricists would not generally deny that we have knowledge of directly observable objects. They would only deny that we have infaillible theoretical knowledge of unobservable entities (or they would attempt to reduce such alledged knowledge to knowledge about observable entities only).

Philosophy of science was dominated by empiricism in the 20th century. However I wouldn't say it's still true today. There was a renewal of scientific realism and metaphysics in the late 20th century building on the difficulties of logical empiricism and Kripke/Putnam's thesis in the philosophy of language for example. It is much more common nowadays to accept that we actually have scientific knowledge of the world, be it approximate or partial knowledge, and that there is some form of continuity and progress even when our theories change.

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