From the Mailbag: The Modes of Aenesidemus

I've been asked to say more about ancient skeptical arguments. An old friend, Charlie Black, writes:

I was wondering when you planned to write more on skepticism. In particular, I am interested in the modes in the early part of Sextus Empiricus' Outlines and whether you can update them into analytic idiom.

Part of the reason I've avoided writing more about the skeptical arguments (in spite of some past posts) is that many are fairly bad.¹ This, for me, makes them less exciting than if they were good. I'm still mainly interested in advancing the lot of philosophy or, at least, showing that it can't be advanced.

Aenesidemus's Modes

One form of argument that shows up again and again in the writings of skeptics is that of the Aenesideman² modes. According to the Aenesideman modes, whenever x appears F to y in situation S, x appears ~F to z in situation S*, x can't be both F and ~F, and there is no reason to prefer the way x appears to y to the way x appears to z, we should suspend judgment over whether x is F or ~F.³

Skeptics illustrate their argument in various ways. For example, in the mode from species, they argue from the different ways x appears to animals of different species to epoche. They, in other words, makes the different “situations” of y and z their each being a different species.

As a second example, they might further argue that even if there is some reason to prefer the way things appear to some species over others, those same things often appear contradictory ways to physically different members of the same species. To put it differently, they might make the different “situations” of y and z their having physical differences within one species.

As a third example, skeptics might argue that even if there is some reason to prefer the way things appear to some members of a species over others, those same things often appear contradictory ways to the different senses of individual members of a species (e.g. Picasso's Portrait of Bibi la Purée appearing smooth to someone's eyes but rough to his touch). They might, in short, make y identical to z and the different “situations” of y and z his perceiving x with different senses.

As a fourth example, skeptics might argue that even if there is some reason to prefer the way things appear to some senses over others (e.g. eyes over noses), those same things often appear contradictory ways to the same senses of individual members of a species in different conditions (e.g. my car might appear different to me after spending a night with la fée verte than before). That is, they might make y and z identical and the different situations of y and z his perceiving x in different conditions or states.

As a fifth example, skeptics might argue that even if there is some reason to prefer perceptions made in some conditions to perceptions in others (e.g. sober ones to drunken ones), those same things often appear contradictory ways to individuals in one condition in different locations (e.g. a cathedral ceiling that appears flat from one position but concave from another). They might, in other words, make y and z identical and the different situations of y and z his perceiving x from different positions relative to x. Through the various examples (and discussions of these modes often amount to little more than long lists of such examples), we're meant to conclude that we can perceive nothing of the true nature of the world. Things appear to us certain ways, but we can have no idea whether this reflects how they really are.

Replies

Dogmatists can reply several ways. They can, for instance, reply that if our sense organs are working properly, we're perceiving under normal conditions of lighting, weather, and so on, and we're perceiving from the right spatial position, our senses must tell us how what we're perceiving really is. Skeptics, however, will argue that they're begging the question by assuming the falsity of the “no reason to prefer” premise in situations fulfilling their conditions rather than arguing for it.⁴

More generally, no one can defeat the Aenesideman modes by simply insisting we prefer perceptions made in some situations over others.

Dogmatists can also reply by adopting a form of dispositionalism. They could, for instance, argue that when we perceive the Baroque ceiling as concave a different array of dispositions is acting on our sense organs than when we perceive the Baroque ceiling as flat. (Is shape really a disposition?) They could then claim that we can learn about the true nature of reality by inferring dispositional properties of things from our perceptions of them.

There are other replies, some of which require venturing into either relativism or Berkeley's subjective idealism⁵, but “brevity is the soul of blog” (Vallicella) and I have other things to do today.

Footnotes

¹. Others are good, but have passed into the philosophical tradition as problems of epistemology (e.g. the modes of regress, hypothesis, and reciprocity are well known problems for foundationalism, and the first and second aetiological modes deal with contrastive underdetermination) and are probably better taken up as part of contemporary debates.
². Aenesidemus is the philosopher who broke from the Academy to form Pyrrhonism. He was probably reacting to the increasing influence of dogmatizers like Philo, over that of skeptics like Arcesilaus and Carneades (both of who were, as I interpret them, genuine skeptics rather than what Sextus would later call “negative dogmatists”).
³. Sextus often gives his arguments in what R. J. Hankinson calls “concessive form”—if not a₁, then a₂; if not a₁ or a₂, then a₃; if not a₁, a₂, or a₃, then a₄; and so on. I've followed this form in my examples.
⁴. The same goes, mutatis mutandis, for those who wish to privilege the results of scientific investigation over other empirical results.
⁵. The relativist and subjective idealist replies are arguably two sides of the same coin: whereas the relativist collapses appearance into reality and says the thing is simply presenting itself to us in different ways relative to our perceptual situation, the subjective idealist collapses the reality into appearance and says we're perceiving distinct sense impressions in each situation and that there is therefore no contradiction. Those interested in the latter should seek out Richard Popkin's “Berkeley and Pyrrhonism”.