Taking a Fresh Look at Antiochus' Criterion of Certainty


Introduction to Antiochus

With Antiochus of Ascalon (c.125-88 BCE) Platonism took a dive back to its roots – or at least, it claimed to do so. Antiochus’ teacher was Philo of Larissa, who was the last of the Academics who were associated with the actual Academy of Plato. Anitochus is considered to be the first major philosopher of the Middle Platonism period. Significantly, Antiochus’ Platonism was no longer anchored to Athens – the city that brought forth Ancient Greece’s greatest philosophers – and instead became associated with Alexandria and Syria (where Antiochus died). His famous students included Cicero, Ariston, Dion, and Varro.

Antiochus' philosophy was an attempt to dogmatize Platonism, and thus opposed the scepticism for which the Academy had become famous. He did this by trying to merge early Platonic philosophy with Aristotelian philosophy - saying that they were both Socratic at core - along with the sophisticated Stoic philosophy of his day.

Some of his ideas included:

  • Happiness depends on both virtue and, to a limited extent, bodily and external goods
  • Ethics revolves around the Stoic conception of "self-conciliation" and the need to adapt to natural purposes
  • Matter is qualified into our world by the Reason of God, aka World Soul - Forms (or Ideas) exist in the mind of God


Antiochus and confident impressions

Antiochus rebelled against the Academy’s skepticism, and was far more sympathetic than his Platonic predecessors to both Stoic and Peripatetic philosophy. Important in his ‘dogmatic’ revival of Platonism was a concept he called kritêrion tês alêtheiasthe criterion of certainty.

Antiochus joined the Stoics in saying that certain impressions must be true, and sometimes we can know that an impression is true because of its feeling, a feeling of absolute certainty1. This is problematic. In a nutshell, the principle problem of epistemology – the study of knowledge – is quite simply “How can we know?” So when Antiochus answers “We know by sensing certainty,” we're not quite convinced. But let’s join him for a bit anyway.

First of all, Antiochus says, we cannot deny that certain simple sense impressions are true: dark, loud, soft, and so forth2. These are seen in combinations, so we see lines and squares and movement, and hear a repeating tone or a sound become louder. When the senses see these in combinations then we grasp objects – like horses and dogs. Objects too can be grasped in combination, and thus we are led to general perceptions, such as “Human beings are rational and mortal”.

Let us begin therefore from the senses, whose verdicts are so clear and certain that if human nature were given the choice, and were interrogated by some god as to whether it was content with its own senses in a sound and undamaged state or demanded something better, I cannot see what more it could ask for. (Academic Priora)

No doubt you noticed Anitochus’ leap from simple sensations to objects. It's not his only one.

How can Antiochus defend this thesis? It’s one thing to say that I’ve absolute certainty about a simple sense impression, but it’s quite another to insist that I have the same certainty about something more complicated, like an object, or a series of objects and their relations. But! it’s only a problem because we’ve made certain assumptions, assumptions which are pretty universal today – whether justified or not. Importantly, we assume that there’s a significant difference between the senses which see the dog and the mind which identifies it as the dog. Presumably, I might say, my eyes take in the colours of the dog and then the mind sticks it together and identifies it as a dog based on previous experiences.

Right there, gloats Antiochus, you’ve split mind and the senses. It’s the chasm between the two, as you conceive them, that’s responsible for introducing fallibility into the system. Antiochus follows the Stoics in saying that the senses are the source of all information, and that mind is a type of sense superior to the other five. The mind is the sense that can recall memories and perform analogical inferences.

This is not as naïve as it may sound, and if you’ll step into my DeLorean with me I’ll show you why.


Your eyes vs the mind’s eye

What sort of information gets into your eye? Technically, all of it. But not in the way that you’d be inclined to imagine. Have you ever opened up a random file with Notepad? Get an image file and open it with your image program of choice. It’s a picture, right? Now open it up with Notepad. Not only is that mess still a picture, it’s the same picture as before. That raw(ish) data you see in the text file is what comes into your eye.

A lot of processing in the brain is needed just to get the raw light data into simple patterns: contrasting colours, lines, planes, relative lightness and darkness, you get the picture.

The question that needs to be addressed here is what do we actually perceive. We obviously don’t perceive the raw data, but how much more processing occurs before we see what we see? If we contort Antiochus a bit then this question becomes relevant. Antiochus assumed that when a simple perception is consistent then we can’t disagree with it. Fallacies arise from misjudgments, and hence anything that doesn’t depend on our judgments can’t be false3. If objects and classes and even higher notions can be formed before we perceive them, then they can’t be false.

Let me ask you, do you see faces as faces, or do you see the sensory data of faces (lines, colours, shapes, shades) which you recognize as faces? For faces, famously, the former is true to an exceptional degree. We employ highly-specialised face-recognition pathways preconsciously. A face is perceived as a face before we can even judge it as a face.

What about other objects – what about dogs and horses? Are they produced by judgment (per the old Academics), or are they the product of the mind’s eye (which the Stoics identified to be a sense)? I believe it’s true to say that most of consciousness depends on preconscious processing. It is before you’re capable of making any judgments that the mind’s eye takes in the raw visual data and transforms it into lines and shapes, and eventually transforms even that into an object, and at some remote stage, transforms that into a particular object class. The more abstract this processing becomes (from our point of view) the less we understand it – for now.

Nonetheless, Antiochus’ criterion of certainty starts to make more sense, and can be anachronistically defended.


Restoring Antiochus in 2010

Insofar as reality exists it can be categorized and described by principles of Bayesian inferencePersonally I suspect this to be a metaphysical underpinning of the world: the world is the sum relation of all things, the patterning of which can be described with absolute accuracy by appeal to infinite sets of regularities which can fit those relations. Which is to say: to say that something is a thing, is to observe that there are commonalities which span multiple identities. Or again: to say that something is a dog is to know that that thing would still be a dog if a second dog were found.

Still not clear, I know. The brain operates by Bayesian inference. At an abstract level, what the brain does is take in data and formulate it into patterns with the purpose of needing less and less energy with each intake of data. It achieves this by remolding its patterns with new data, to make integrations easier. Essentially this is why we expect things, or why new things surprise us, or why we can divide the world into categories of things – like dogs and horses. It also forms the basis for long term potentiation - the molecular mechanism for forming memories.

If reality and consciousness can both be described by the principles of statistical regularity, then Antiochus might be right that I can defend my ideas by saying that they’re clear. By "clear" I have to mean that they are not imposed on by my own judgements.

The problems that remain in 2010 are problems that Antiochus in his own day too failed to resolve: How abstract can our thoughts become before our judgments impinge on them? And how, for that matter, can we know whether our preconscious conceptions have been tainted by consciousness?

I would add another problem, and a tentative solution: If cognitive processes are dependent on preconscious necessity of deriving patterns from the world’s data, then how can we be sure of the data we’re receiving? We can’t, we’re innately limited. Our only criterion of certainty is the world in its entirety. And so, to seek to know the world is our only choice.



1 Straight off the bat Antiochus makes sure to exclude experiences like dreams and hallucinations by defining them as abnormal. This brings a whole host of assumptions and problems of its own, which I won’t go into here.  Food for thought: what does it mean that waking consciousness is “normal”, and if that is the case, then what does it mean for normal consciousness to be distorted by a dream? Do we perceive dreams or are we distorted by them?

2 As with the problem of dreams, Antiochus here too makes sure to exclude problematic cases. The famous “Oar in the Water” and similar cases are not considered relevant since they are deceptive, but only insofar as they provoke us to investigate them. These cases encourage us to alter our perceptions until we can gauge them better and properly.

3 With all the obvious exceptions excepted; see the above footnotes from what sorts of experiences Antiochus excluded. Misjudgements are possible in the Academy's Platonism because the Mind acts on the Senses. It’s not clear to me what Antiochus’ source of misjudgements is – perhaps something to do with Will overstepping the senses' boundaries.

A final note: Why is this writeup focused on Antiochus and not the Stoics? Two reasons: (1) I did not initially appreciate the extent to which Antiochus' criterion was a copy of the Stoic criterion of cognitive impressions. (2) When later I did realise, I tried to see if there was a way to keep the writeup on Antiochus, and came up with the following: Insofar as I can tell, Antiochus' proof of his criterion of certainty depends on an appeal to the senses, and so fits in with my argument better. I've inserted the relevant primary quote (taken from Dillon) into the text above. Basically the implication is that Antiochus' criterion depends on the argument that the function of the senses is analogous to the mind's eye (nb. this is my phrase not his) and hence as reliable as the senses. Similarly, my "update" of Antiochos depends on the suggestion that the same principles of neural processing that make possible "simple" perceptions (like line and shade) are also what make possible the perception of objects and object classes.


Check out The Middle Platonists by John Dillon, The Bayesian Brain by D.C.Kill and A.Pouget (2010) Trends Neuro, and Vision as Bayesian Inference by A.Yuille and D.Kersten (2006) Trends CogSci.

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