Saturday, May 24, 2008

Seeing yellow II

Thank you all. Some very helpful info:

Gábor writes:

Hi, I was reading your blog on seeing yellow. Here is what Sherlock and Dooley write in their Diseases of the Liver and Biliary System: 'In deep jaundice, the ocular fluids are yellow, and this is considered to explain the extremely rare symptom of xanthopsia (seeing yellow)' (10th ed., Blackwell, 1997, p. 207). 'Extremely rare' I think is telling; I wonder if it is not a way of saying that we are not quite sure whether this symptom really exists, but there is this whole tradition.... I also vaguely remember the Geoffrey Lloyd wrote something about it in 'Observational error in later Gr. science.'

...and then...

'I checked and there is a long footnote on this issue in 'Observational error...' (fn. 2 on pp. 303f in the reprint in Methods and Problems...). By a survey of some authoritative medical books (he does not mention the one I was quoting) Lloyd shows that whenever there is a change in the wording of the successive editions, authors become more and more tentative about the existence of the symptom, but on the other hand, many books keep referring to it. Lloyd concludes: 'The repetition of this idea is remarkable testimony to the tenacity and conservativeness not just of popular belief but of medical opinion. Mr W.N. Mann, who confirms that he has not encountered a case of xanthopsia in jaundice, has remarked to me (personal communication) that it is striking that the matter has not been tested by a post mortem examination of jaundiced subjects to establish whether the media of the eye (aqueous, vitreous) and/or the lens is discoloured.'

I wonder whether such an examination has been carried out since 1982.'

So, there you have it. There is a weight of antiquity and, perhaps, simple prima facie plausibility behind this thought sufficient for it to be repeated as true and therefore not tested. Of course, for the Cyrenaics' point (which is why I originally wondered about the phenomenon) it only needs to stand as one example of a set intended to make the general point that it is reasonable to think that the way things appear to one is sometimes mistaken. You'd think that nevertheless they would be best served by examples which are familiar from general experience...


Clerk said...

Sextus reports on the Cyrenaics:

...but that what is affecting them is yellow or red or double is considered [νενόμισται] false, so it is also overwhelmingly reasonable that we are able to grasp nothing more than our own pathē.

You gloss their use of the jaundice case this way:

it only needs to stand as one example of a set intended to make the general point that it is reasonable to think that the way things appear to one is sometimes mistaken.

But the point that Sextus reports is rather different. If the Cyrenaics thought that this example demonstrated the possibility of erroneous πάθη, then they wouldn't claim that the πάθη were κριτήρια and especially not that they καταλαμβάνεσθαι καὶ ἀδιάψευστα τυγχάνειν! Rather, they're making an ad hominem argument (νενόμισται) by equivalence. Those who admit some other κριτήριον than the πάθη think that certain πάθη are erroneous (the visual πάθη of the jaundiced are an example of the ones that such people consider erroneous). Such a πάθος is not, on such people's account, criterial for the nature of its cause. But those people have no principled way of distinguishing the purportedly erroneous πάθη from the veridical πάθη. (This seems to beg the question by assuming that they have no other reliable κριτήριον, so my reconstruction may be thought uncharitable to the Cyrenaics here.) So, if the targets of the argument want to maintain that there is any κριτήριον, then they are committed to considering all πάθη to be criterial, though not of the nature of their causes--the Cyrenaic view. (Skeptics run a similar argument in order to cast doubt on the claim of the πάθη to be considered κριτήρια at all. Another passage that might be interesting in this relation is the section in Outlines where Sextus contrasts skeptics and Cyrenaics--but I don't have it handy.)

JIW said...

I think the Cs' point is not to distinguish between two kinds of pathê but to point out precisely that we can apprehend that we are experiencing a certain pathos (i.e. we cannot be mistaken about the fact that we are being 'whitened') whereas the agreement that it is possible for this pathos to be caused both by something white and something non-white shows that we cannot apprehend by means of the pathos that the object which causes it is of a certain nature.