I think, therefore -

Central to Descartes' philosophy is the clear and distinct idea.  If we perceive something with a real clarity which admits of no doubt, then we may accept its truth.  Provided, of course, that there is a God whose perfection necessarily guarantees that He is no deceiver.  God's existence we can deduce from that sense of perfection which complements our innate sense of imperfection.  And that innate sense is rooted in Descartes' most famous proposition: 'cogito, ergo sum' - I think, therefore I am - a privileged concept which must be true, no matter how deceived we are in all other respects.  If I am deceived, I exist.  And so on that one bedrock certainty, the edifice of Cartesian philosophy is built.

The clear and distinct idea may seem, paradoxically, to be far too vague a method with which to construct that edifice.  And yet we have probably all experienced the reality and power of that feeling in studying mathematics.  Indeed, it was from the pure and perfect certainties of mathematics that Descartes drew the original inspiration for his clear and distinct idea: he was gripped by the unique sensation of understanding the steps of a theorem - truly seeing them with a blinding clarity as if gazing directly at the countenance of reality.  He was doubtless also struck by the concomitant sense of grasping the totality of a mathematical proof.  When we fully understand a proof, it is not just the individual steps which we see clearly: we also hold the sum of them in a simultaneous vision.

It is an exhilarating feeling.  I shall never forget half a day I spent at university trying to comprehend, to hold in my head, the steps of a particularly profound but recondite theorem in General Relativity - Hawking's so-called Second Law of Black Holes.  Gradually each part fell into place.

Then, as the last lemma in the demonstration was lit up by my strained understanding, for a few glorious moments the whole amazing proof stood present in my mind - not as a series of hard-won and tiny illuminations, but as a complete and single blazing truth.  It was like unbolting a long series of doors, and then placing myself so that through their aligned openings I could see a vision of paradise. The sensation lasted for a few minutes only, as if the mental energy required for this feat was too great to be sustained for longer.  The alignment was lost, and the doors began to close.

It is not just in the rarefied atmosphere of mathematics that we encounter these manifestations of the Cartesian clear and distinct idea - or its absence.  How often in reading do we find the words suddenly drop out of focus, convey no meaning as we lose the thread, as our concentration vanishes?  And talking with someone we can in an instant find ourselves in the middle of a sentence without any idea of its destination, lost amidst a babble of sounds.  To talk and write meaningfully and transparently we must have within us that sense of the step-wise progression building to an overall argument.  Losing that sense is terrifying, because it threatens a loss of our selfhood's defining function of a coherent viewpoint; but running with it, either in speech or in writing, is to experience and embody consciousness at its most clear and distinct.
 
(25.11.89)

See also Moody Sonnets - AI’s Secret

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