COGITO ergo sum. I think therefore I am. Rene Descartes’ classic aphorism is widely known and he first wrote it in his native French to reach a wider audience – je pense donc je suis. That sounds softer to me than the rather stark Latin we know it as today. But what does it mean and why was it important to Descartes?
He first used it in 1637 in a piece about how our senses deceive us. We are quite happy to say that the sun rises in the morning and sets in the evening, but that’s only how we see it of course.
As a 12-year-old schoolboy, Descartes was stunned when he heard of Galileo’s new finding that Jupiter had moons orbiting it. Copernicus has published his heliocentric model putting the sun and not the earth at the centre of the solar system just before his death in 1543 but his complex mathematics made it unreadable to all but top-class astronomers.
What was needed was a simple illustration that not all objects in the night sky revolved around the earth. Jupiter’s moons gave just that view of the universe. Suddenly Descartes realised that what seemed obvious to his senses – that the earth is standing still and that the sun and moon are rising and setting – was wrong.
If we can’t be sure of what our senses are telling us, what can we have as our foundation? Just that I am thinking, said Descartes, that is all that I can be sure of.
“Well,” you say, “that is all very interesting in the deep philosophy of the early Enlightenment, but what does it mean for us today?”
Let me pass another Latin phrase by you. Post hoc ergo propter hoc: after this, therefore because of this. I’d like to be able to tell you who first said that but even Wikipedia couldn’t help me there.
What it did give me was a useful example of the phrase: the cock crows just before the sun rises. But nobody in their right mind would suggest that the sun rises because the cock crows, would they?! Where is this going, you ask…
A few weeks ago a friend of a friend asked me by e-mail if I could see their cat with a nasty eye. They provided me with a virtual image of the animal with a red eye with blepharospasm and third eyelid protrusion.
My differentials were trauma, foreign body, chlamydophila, mycoplasma, feline herpesvirus…that was about it. I just needed to call the cat’s normal veterinary surgeon to get the OK to examine the animal and then we could easily arrange an appointment.
And thus it was the next morning when I was on the phone to the veterinary practice when lo and behold a second e-mail came winging its way through the ether.
The cat, a rather lovely Siamese, was now after a good night’s sleep completely normal. A second image confirmed it – my services were no longer required. And that got me thinking. If I had seen the cat the day before and prescribed an eye-drop: trifluorothymidine maybe for FHV-1 or a topical nonsteroidal perhaps. Or maybe if I had given a systemic antibiotic per os.
Any treatment that gave this remarkable turnaround would be wonderful, wouldn’t it? I would most likely have put the improvement down to my treatment regime. It stands to reason, doesn’t it? I give treatment and then the animal recovers – success! But here all I did was leave the cat for a night and hey presto – a result!
Post hoc, ergo propter hoc? Just because the animal recovered does not mean it was because of what I had treated it with. And that’s the importance of doing a controlled clinical trial of a new treatment rather than amassing a set of clinical cases where the drug worked and expecting it will give the same evidence – data is not the plural of anecdote!
In fact a surprising number of animals I see as referral cases have recovered by the time I get to examine them. I tell the owners that this is David’s Distance Healing Ministry and that unfortunately the ministry does come at a cost! Most take the joke well and we just share the pleasure that the animal has healed itself.
I did have one owner who asked me how far the healing ministry extended – he had a friend with a dog suffering from cataracts in New Zealand; could my powers reach that far? After several minutes trying to persuade him it was a bit of fun I realised that the only way was to be perfectly serious and admit that the distance healing wasn’t international!
That reminds me of a time in London when my ophthalmic clinic included a useful dog eye chart with one large lamp-post, two smaller cats, four even smaller postmen and six diminutive bones.
It was a jolly addition to a rather drab wall in the clinic but I took it down when too many owners honestly thought I could assess their dogs’ vision with it. So I should have learnt my lesson when on our internet ophthalmology listserve an e-mail came asking who Finhoff was, he of the Finhoff transilluminator, a simple device producing a beam of light for ophthalmic examination.
Not knowing who he might be, I wrote a piece on Finhoff the Norse god of the dark, banished to the underworld by Thor for having an affair with his wife Sif. Finhoff roamed this nighttime land, so I said, with only a single beam irradiating from his forehead to light his way, hence the Finhoff transilluminator.
The trouble is that internet humour seems completely lost as it traverses the Atlantic: I spent much more time than the joke had taken to compose, trying to dissuade the Americans from being quite so impressed with my apparent knowledge of ancient mythology!
And the way I started this perambulation might have made it sound as if I am quite an expert on Rene Descartes. But Professor John Cottingham is the real expert – his great biography is only a penny on Amazon new and used.
Dave Robinson’s Introducing Descartes – a graphic guide is similarly priced but a darn sight easier to read – those books will help you sound as if you know Descartes back to front.
I will tell the students who come to study in October that they have six years to learn enough jargon to persuade pet owners that they know what is wrong with their animals. That in itself is a bit of a joke, of course, but if you have read these little offerings before you will realise that with me that’s quite to be expected!
