This paper aims to discuss Sextus Empiricus’ third mode in Outlines of Pyrrhonism, Book I. I will first analyze the progression of Sextus’ argument in reaching the final conclusion, then moving on to investigate the strength of his argument and provide the mantis shrimp example to support Sextus’ conclusion.  

In Outlines of Pyrrhonism, Sextus concludes that we should suspend judgment when perceiving an external object, as the senses each person possesses are most likely not the most accurate and complete representation of the qualities of its nature. Sextus reaches this conclusion through the following steps of argument: 

First, Sextus claims that the same object can appear to have multiple properties to us because of the senses we have. The nature of an object doesn’t change, but the senses which an individual possesses may affect our impressions of the images of the object in our minds. Therefore, we can only say how each object appears to us in the present, rather than that we know the object’s true form. (Book I, 92-95)

Next, Sextus illustrates an example of a blind/deaf man who is unable to perceive and comprehend the existence of visual/audible objects. Sextus argues that, similarly, people with all five functioning senses may also lack other sense organs that could allow us to “apprehend the sense objects which come through them.” Is it completely possible that there exists other senses which would allow us to perceive new objects in ways we cannot comprehend with our current senses — just as how it is impossible to explain what objects look to a man born without sight. (Book I, 96-97)

Thus, we are unable to determine what the nature of the apple really is because “it is possible that only those qualities which we seem to perceive subsist in the apple, or that a greater number subsist, or, again, that not even the qualities which affect us subsist.” (Book I, 99)

What makes Sextus’ argument convincing to most readers would be his success in providing strong evidence to support his premises — more specifically, how the human senses may be capable of making us perceive more or less properties of the object than there actually is because there is an equal possibility of (i) us perceiving more qualities of the object than there actually are because of the senses we possess or (ii) us lacking other senses, which inhibits our ability to perceive objects that we cannot comprehend with our current sense organs. 

Additionally, the examples which Sextus employs to strengthen his evidence includes objects whose qualities most people are familiar with. For instance, to illustrate premises (i), Sextus uses the examples of honey, sweet oil, rainwater among others. Honey is pleasant to tongues but not to eyes; sweet oil is pleasant to nose but not to tongues; rainwater is beneficial to the eyes but not for our lungs, etc. 

Sextus refers to the man who lacks sight and hearing since birth to further support premises (ii). He draws a comparison (from the perspective of someone with all five functioning senses) between those like the blind man and those like himself. On the other hand, though it is impossible for us to compare ourselves to humans with extra senses, there are other organisms which have sensory organs that humans don’t possess. The mantis shrimp, for instance, has 16 color-receptive cones in contrast to humans’ 3 cones, which means that they are able to see more colors than us. Our minds have no way of comprehending what objects appear to be like for mantis shrimps: we may see that an apple is red, but what do mantis shrimps see? They could also see it as “red” in the same definition as us; it is also completely possible, at the same time, that they perceive the apple to be in a color which is not defined in human language.  

In conclusion, Sextus’ argument of the third mode that we should suspend judgment due to the unreliability of our senses is convincing in that he is able to provide the common objects in an undeniable, factual way. In doing so, his argument appeals even to those who may not necessarily share his viewpoint.