‘Philosophy’ has neve been Wisdom. Chaper 6: Descartes on Knowledge

It is another example of the pottiness of Philosophy. This first page down to the first horizontal line gives the nub: 


In about 1637 AD, he wrote, ‘Cogito ergo Sum’ – ‘I think, therefore I am’. 

Did he really think as an adult person that he couldn’t believe he existed until the logic of words proved it?  

Furthermore, ‘Cogito ergo Sum’ only led him to the conclusion that his mind, which was doing the thinking, existed, not his body.  You see, his senses may be fooling him that he had arms and legs.  They had sometimes fooled him in the past.

It was only from the logical certainty that his mind existed, that he could arrive at any other truths, and by way of logical deduction.

Descartes was too sceptical to trust any of the philosophizing of the previous 2000 years! Didn’t he consider the earlier philosophers to have been as rigorous as he was himself?  None of it gave him absolute certainty.  He wished to start all over again with a self-evident axiom and then work further from it by deductive logic to establish other certainties as in mathematics.  This was his ‘methodological scepticism’, or what he called his ‘mathematical method’. 

But Descartes later did a volte-face, jettisoned his Cogito ergo sum, and came to trust his senses, that he existed among other things!

He started moving toward trusting his senses by the most amazingly feeble arguments that God existed!

The main one was pretty much Anselm’s of 600 years earlier: ‘God exists in my mind as the Greatest Being.  Existing in reality must be a quality of the Greatest Being.  Therefore God must exist in reality.’1

This quality of argument is dignified by the title ‘Ontological Proof of the Existence of God’.   I can only think it is called ‘ontological’ because it goes back to Parmenides’ Ontology which says, ‘If you can think it, it is….’.2

That was a proof of God! and it led Descartes to trust his senses! This was because he couldn’t for some reason of the time believe that God was a Great Deceiver who would deceive Descartes about what his senses told him.  It was God after all who had given Descartes his senses!

So Descartes could now accept that his mind existed, and discard Cogito ergo Sum entirely!  Brilliant!

It was from a proof of God, and such a one, that Descartes came to trust his senses!

Descartes has gone down in the history of Western philosophy for ‘methodological scepticism’, for ‘epistemological idealism’, and for ‘Cartesian Dualism’; and as ‘the first modern philosopher’, and one who ‘provided a foundation for the natural sciences’.   My mind boggles.

(The following 3 pages expand on the above.  Take them easily.)


So Descartes, in his Cogito phase, couldn’t trust his unreliable senses.  He wished to establish what was definitely true by purely rationalistic means in his head. 

A famous example by Descartes of his senses proving wrong was that honey was runny when warm, solid when cold, yet was still hon ey!  Descartes also reasoned that it was possible that what came to him through his senses might be in a dream; or that God or a wicked demon might be deceiving his senses.

But, as I think Ayn Rand (an enthusiast for Philosophy) sanely pointed out: we all rely on our senses to correct the few occasions when our senses deceive us.

To my mind, believing what comes to one by logicking, rather than by the senses, is crazy.  This applies to the logicking of Parmenides’ Ontology in about 475 BC (see my chapter on the pre-Socratics) just as much as to Descartes.

My unphilosophic mind also fails to see that Descartes in the early 17th century turned over a new leaf for Philosophy. It seems to be the same old ‘Rationalism’ (in its special philosophic sense) as opposed to ‘Empiricism’.


It is amazing that Anselm had had the nerve to put forward his proof of God.  Parmenides’ idea was potty in 500 BC, Anselm’s in 1078, and Descartes’ in 1637, but subsequent philosophers have still thought it worthwhile to take it seriously. 

It is said that Descartes wished to be able to deduce that God existed, because he was really a believer deep down, and because he needed to avoid Church persecution.

Descartes, it seems, used a number of other arguments too for the existence of God.  There was one similar to Aristotle’s argument that there has to be a First Cause for anything that exists or happens.  Also a ‘Causal Argument’ — that if one has an idea of something, then there must be a cause of this idea at least as real as the idea itself.  This latter argument may have come from Augustine’s neo-Platonism, although it seems to me similar to Anselm’s.  There was yet another argument, similar perhaps to another of Aristotle’s, but I haven’t quite got hold of it. 

These proofs of God rested on a priori metaphysical arguments, not on the a posteriori sensory evidence which is taken seriously today. 

Descartes could also now believe that he did have a body with arms and legs, and that the outside world did exist, and that he hadn’t really needed his Cogito ergo Sum and his Methodological Scepticism to start with.3  Brilliant!   

I found it difficult to credit what Descartes seemed to be saying in his Cogito phase, and how he got to his second.  This was partly because I had thought that Empiricism (trusting one’s senses in their observing and experimenting) had by 1637 AD taken over from purely Rationalistic logicking as the way to Knowledge.    But perhaps scientific method had only recently started, and only started influencing Philosophy in Britain.

It is said that Descartes could have given the ‘naturalistic’ argument ­­­-­­­- that the orderliness of nature is evidence of a Creator — but he didn’t.  He might have seen it to be a circular argument in that the perception of nature was by the senses that God had given him, so he would have had to believe in God to start with!

A big thing is made of Descartes’s ‘clear and distinct’ perceptions by the senses. But I don’t know what he meant by it or whether he said it in his Cogito or post-Cogito phases. 

Some philosophers point out that Descartes’ proof of God’s existence contained ideas that Descartes assumed to be ‘clear and distinct’ which already assumed the reliability of the God-given senses.  So he proved God’s existence by assuming God’s existence!.

I also don’t quite understand Descartes’ statement that, even if a demon were deceiving his senses, his mind would still have to exist for this demon to be deceiving it.4

These thoughts of Descartes seem to me so pottily rationalistic to the point of irrationality that I may well have got his further thoughts and their sequence not exactly correct in what follows.


According to the Cogito as conceived above, Descartes thought of it as a logical deduction from the fact of his thinking to the existence of an agent doing the thinking.  

But some philosophers say that Descartes also thought of Cogito ergo Sum as meaning ‘the certainty of first-person experience’ or ‘intuition of his own reality’ or ‘logical self-certification of self-conscious awareness in any form’. 

It seems that Descartes himself wrote that ‘I am’, that he exists, is an immediate intuition, and not the result of a line of logic about which he could be deceived; therefore it is certainly true, presumably because it was a result of his senses perceiving his mind and body.5

But Descartes wavered: he later wrote that his Cogito is a syllogism whose premises are ‘I think’ and ‘Whatever thinks, must exist’. 

But, even granting it to be logic, some later philosophers were worrying whether it is logical to conclude that if thinking is occurring, there has to be an ‘I’, or anyone or anything else, doing the thinking!

How idiotic that all this, including my own tiny arguments, can be considered as Search for Wisdom!

It has been pointed out that Descartes in his Cogito could be defined as an ‘epistemological idealist’ in that he was certain only that his mind existed, and that the external world was just an idea or picture in that mind and may not really exist on its own.  (Phew, that’s Philosophy!)


It is said that one consequence of Descartes was that thinkers could now investigate the world by deduction or by sensory perception without fear of the Church.  This was apparently because Descartes had proved that God existed and that He wasn’t a Great Deceiver, and that one could trust the senses that He had given us.

So it became theologically permissible for thinkers to investigate the world by thought or by scientific method using their senses, because they had already accepted God’s existence.6

(Had the Church previously frowned on investigations of the world, because it implied dissatisfaction with what the Bible said on the world?)

But it seems that Descartes also helped Philosophy become an enemy of Religion.  Here is an excerpt from George Heart’s Christianity: Dogmatic Faith and Gnostic Vivifying Knowledge that I edited myself:   ‘Philosophy was independent when it began, but then Christianity appropriated it for defence of the faith, showing faith to be in accord with Reason.  Reason/Philosophy was seen as a helper of religion.  This came to a peak with Scholasticism.  Descartes broke philosophy free from religion.  That is his importance as Father of Modern Philosophy.  Reason on its own could now understand God, universe and man.  It had its own validity apart from divine inspiration.  Philosophy became an enemy of religion.’

(Is this then why Descartes is regarded as so important, which is so puzzling to my unphilosophic mind? – that he broke Philosophy free of Religion?)

Did Philosophy become independent of revealed Religion partly at least through Descartes showing that Reason could prove the existence of God without the revelations in the Bible?  (But Descartes’ proofs by Reason were ludicrously feeble.  And the God he proved was a deistic one of Reasoning, not specifically the personal God of Bible and Church.)


To help me to justify my view of the kind of mind Descartes had, I note that he contributed original work to mathematics and to science.7,8

He invented analytic geometry, provided the basis for calculus and ‘thus for much of modern mathematics’, and did seminal work in optics. So he was a towering figure in maths and science, let alone Philosophy.

Yet, (against my disdain for philosophers as having logicking, mathematicking and scientificking minds) he said, in his Discourse on the Method, that: early in his life, he ‘abandoned the study of letters.  Resolving to seek no knowledge other than that which could be found in myself or….in the great book of the world, I spent the rest of my youth travelling, visiting courts and armies, mixing with people of diverse temperaments and ranks, gathering various experiences, testing myself in the situations which fortune offered me, and at all times reflecting upon whatever came my way so as to derive some profit from it.’  He was even a military mercenary. 

Anyway, that’s what he said about himself.



Descartes’ dualism, the difference between mind and body:

Descartes proposed that some things such as the brain are material, and others such as the human mind and God are spiritual.  You don’t say!

It was the one fraction of his thought that later philosophers weren’t impressed by.  I cudgel my brain to understand why.  It was given the title ‘Ontological Dualism’ or ‘Cartesian Dualism’.

For me, it has always been a telling error to think that the verbal logicking of philosophers can solve the conundrum of the relationship between brain and mind.  It is part of the wrong-headedness of Philosophy to think it can.

For all that, ‘Cartesian Dualism’ became the basis for ‘The Mind-Body Problem’9. Why is it a problem?  Didn’t philosophers think it ‘clear and distinct’ that the brain is material and resides in the skull, and that the mind (consisting of feelings, thoughts, dreams, nostalgias, behaviours, desires, cultures, civilizations, tastes in reading, tastes in carpets, ironies and responsibilities) isn’t material.  Yes, it resides in the brain, develops from it in the course of evolution and of the individual’s life, is damaged if the brain is damaged; but is itself a great ethereal bubble that can’t be described in material terms.

Did philosophers seriously believe that everything is material, and that the mind or ‘self’ is just the brain?

Were these only the grim materialists of modern times but earlier philosophers too?  To me, the idea that all these constituents of the mind or self will one day be explained as electrical impulses in nerve cells, is the product of minds with an impoverished self-experience of mind and self.

Some thinkers, for example Paul Dean on Leavis10, think that ‘the mistaken equation of “brain” with “‘mind”  is one of the most insidiously misleading examples of modern sophistry’.   That he thought it worthwhile to say so, makes me think that modern minds do on the whole think that the mind is just the brain that scientists study.  My mind boggles.

I met a boy at college long ago, who expressed the thought that one day all thoughts and feelings would be analyzed down to electrical impulses in nerve cells.  My mind boggled that anyone so benighted could get into college.  But I was wrong: This was exactly the kind of mind that Academia valued.

It seems that Descartes’ theory that mind is basically different from body and brain was a revolutionary idea in his time, even though science had barely yet started to influence general ideas about the mind.  He hoped that his dualism would satisfy the Church that it could continue to act in the spiritual world of Mind and God, and leave scientists to do empirical investigation into the material and mechanistic world11.

Some moderns think that Artificial Intelligence is like the human mind!   I too feel it is, to the extent that so many modern peoples have a mechanical intelligence with banal ideas of human life.

Yet the legal systems of countries still assume the self to be mostly independent of biological or physical causes, and to be responsible for most of what it does, and therefore can be found guilty and sent to jail.

Because Descartes was so materialistic and mechanistic, he needed to find an exact spot where material brain and spiritual mind interacted.  He picked on the pineal gland (a small comma hanging off the bottom of the brain) as that spot where intentions from the Mind crossed into the Brain to give rise to muscular movements, and where pain sensations from the brain crossed into the mind.

Later philosophers didn’t think much of the pineal gland as being where Brain and Mind interacted, and thought up other theories such as Materialism, Idealism, Behaviourism, Occasionalism, Epiphenomenalism, Pre-Established Harmony, and Double Aspect Theory.  Look these up; they are amazing.

To pick on the pineal or anywhere else is the sort of thing a rationalistic mind would do to providee an answer to something unfathomable.

Descartes, very wisely for a change, wrote late in his life that ‘the union of mind and body is best understood by not thinking about it, and that it is just one of those mysteries that has to be accepted without being comprehended’12.  Exactly!  But moderns think that neuro-science will one day solve it.

Philosophers use logic to try to solve what are imponderables to logic, but these imponderables remain imponderables by the very nature of imponderables and of logic.

It seems that Descartes believed that our minds carry on after our brains have died.  Modern scientists don’t.  They believe that brain is mind.


  1. http://www.philosophypages.com/hy/3f.htm
  2. https://en.wikipedia.org/wiki/Ontological
  3. http://www.netplaces.com/philosophy/ren-descartes-the-father-of-modern-philosophy/descartess-agenda.htm
  4. https://www.britannica.com/topic/cogito-ergo-sum
  5. https://www.britannica.com/topic/cogito-ergo-sum
  6. https://www.philosophybasics.com/philosophers_descartes.html
  7. http://www.edinformatics.com/great_thinkers/descartes.htm
  8. https://www.famousscientists.org/rene-descartes/