Profiles in skepticism: Carneades

The philosopher for whom belief comes in degrees

Marble head of Carneades by Osama Shukir Muhammed Amin, image from Wikimedia.

One of ancient skepticism’s towering figures was without a doubt Carneades of Cyrene (214-129 BCE), who became scholarch of the Academy little over a century after Arcesilaus turned Plato’s school in a skeptical direction. Like other skeptics associated with the Academy, Carneades’ driving idea was to go back to Socrates’ dialectical approach to philosophy and to his famous admission that he didn’t know much. Socrates, according to the Academics, was the original skeptic.

Arguably, Socrates had devoted himself to the pursuit of three aims: (i) making people realize that, despite their assumptions to the contrary, they believe a lot of things that are not true; (ii) subtly hinting at the most likely answers to the various philosophical problems being debated; while (iii) hiding his own convictions so not to unduly influence his interlocutors. Carneades followed this same three-pronged approach to philosophical dialectics, one that is practiced still today under the broad term of “Socratic method.”

Carneades, like Arcesilaus before him, focused his criticism on the dominant school of the time: Stoicism, and particularly on Stoic epistemology, the branch of philosophy that deals with how we know things. More precisely, he rejected the Stoic idea of “kataleptic” impressions, that is impressions that somehow bear a mark of truth that can be detected by a sage.

Recall than an “impression,” in Stoic-Skeptic lingo, is an immediate judgment that is prompted in us either by a sense experience or by an internal thought. For instance, “I see my brother across the street” is a sense-generated impression. Notice that I am not just stating a fact, but rather a fact+judgment. The fact is that I perceive something out there that looks like a person. The judgment is that I believe that person to be my brother.

Impressions can also be internally generated. If I think “the square root of nine is three” I am also having an impression, which is not triggered by a sensorial experience. Just like in the case of my brother, I may also turn out to be correct or incorrect in my judgment that the square root of nine is, indeed, three. If I agree with the initial judgment I am “assenting” to the impression. Otherwise I am denying assent to it.

Now, the Stoics thought that some impressions are special because they bear a mark of truth that definitely separates them from false impressions. Moreover, that mark of truth can be recognized by sages, that is by human beings who have achieved perfect reasoning ability. I know, it sounds far fetched, but bear with me just a bit longer.

These special impressions were named “kataleptic” by Zeno of Citium, the founder of Stoicism. Katalepsis means “to grasp,” indicating that we can grasp the truth of such impressions—again, if we are sages.