René Descartes (1596-1650)
Descartes is often considered the founder of modern philosophy; he was the first philosopher whose work was affected by the new scientific breakthroughs, in physics and astronomy, of the time.
Having travelled across Europe, enlisting in various armies to try and gain insight into life through action, he settled in Holland in 1629 where the right to freedom of speculation allowed him, as well as Hobbes, Locke and Spinoza, to think, write and publish work freely and without persecution.
In 1637, he published “Essais Philosophiques” which looked at geometry and optics and in 1644 he published a book setting forth most of his scientific theories: “Principia Philosophiae”. He also wrote “De la formation du foetus” in which it is regarded that the bodies of men and animals are machines. Whilst animals are “automata” and governed by physics, devoid of feelings, men have souls (residing in the pineal gland in the brain). According to Descartes, this soul comes into contact with ‘the vital spirits’ and, through this, there is interaction between soul and body. This theory was abandoned by his schools as the conservation of momentum disproved this – as the total momentum in all direction must remain equal, it is not possible for the mind or soul to physically interact with the body without altering this, therefore mind and body must be separate.
His books “Discourse on Method” (1637) and “Meditations” (1642) are purely philosophical yet largely overlap, according to Bertrand Russell’s “History of Western Philosophy”. From these, we get ‘Cartesian doubt’ – “I think, therefore I am” or “Cogito ergo sum.” According to this, everything can be doubted to exist except some form of yourself; as you can doubt your own existence or the existence of other things, you must exist so that you can doubt it - even if you only exist in the mind of someone/something else, you still exist in some form. Therefore knowledge can only come from the mind, not the senses as what is observed can be doubted as it could be imaginary. So, when something is not being observed, does it exist? In my mind, physics states it must as everything is made of fundamental particles which cannot be called in and out of existence at will. However, as particles are only known as they observed, they cannot be considered to be known, so theoretically may not exist, though Descartes states that geometry and physics can be known, which, to me, creates a paradox.
Also, if there are two different ideas of something, “the one which comes directly from experience must be the less like it of the two” and in the example there is the example of the Sun “as it appears to the senses and the sun in which astronomers believe” but, as the ‘knowledge’ that astronomers believe about the sun has come from observation (a sensory experience) it too can be doubted, which makes me wonder if there is any difference in the two ideas’ closeness to the truth.
Baruch Spinoza (1632-77)
Spinoza’s family moved from either Spain or Portugal to avoid the inquisition. He was excommunicated by the Jews and abhorred equally by the Christians. He was offered 1000 florins to conceal his doubts but refused (much like Socrates, who refused to stop teaching philosophy so, instead, took the death penalty). After he refused to conceal his doubts, there was an attempt to assassinate Spinoza and, when this failed, he was cursed to be attacked and killed by a she-bear, which never came true.
The political theory in his books “Tractatus Theologico-Politicus” and “Tractatus Politicus” is, in some respects, derived from or in agreement with Hobbes in that both agree:
1) The state of nature contains no right or wrong as there is no law to disobey
2) That the State is to stop beliefs being forced upon citizens (i.e. religion is subordinate to state)
Spinoza argues, in his book “Ethics” that there is just one substance – God or Nature (unlike Descartes’ idea that there are three – God, mind and matter) as thought and extension are attributes of God, who has an infinite number of attributes. This is known as Spinoza’s monism, which is to say that the one fundamental substance is neither mind nor matter but is capable of becoming either. He says that substance is that which:
1) Is a cause of itself
2) Can be conceived of by itself (i.e. “I think, therefore I am”)
3) That which need only itself on order to exist
These principles mean that substance must be intelligible without relations to other things and so must exist in order to be independent and therefore must exist alongside everything else which exists and be part of one thing, i.e. God/nature.
Gottfried Leibniz (1646-1716)
Leibniz was born two years before the end of the Thirty Years’ War and his father was a professor of Moral philosophy. In 1666, Leibnitz gained a Doctor’s degree in Law.
His theory of ‘monads’ can be found in “Monadology” and “Principles of Nature and Grace”. Monads “are to the physical world what atoms are to the physical/phenomenal” – they are the ultimate elements of the Universe. They are “substantial forms of being” that are:
1) Eternal
2) Indecomposable
3) Individual
4) Subject to their own laws
5) Un-interacting
6) Reflecting the universe in “pre-established harmony”
These ideas had been developed from Descartes. They suggested that it was a centre of force or that “substance is a force whilst space, matter and motion are phenomenal”. This means that monads have no special or physical characteristics, unlike atoms, therefore they do not have to be small. Also unlike atoms, monads follow “instructions” so only appear to interact; God wills the pre-established harmony which these monads follow. This creates a problem with free will. However, Leibniz’s “principle of sufficient reason” states that, as nothing happens without a reason, the reason for a “free agent’s” actions are “without necessitating” which means that whilst these actions have motive and reason, they do not need to have a logical necessity.
From this, there can be 4 arguments in which metaphysics can ‘prove’ God:
1) Ontological – whilst “essence” (personal qualities) do not imply the existence of humans, it does imply the existence of God, as the most perfect Being as, if he does not exist, he cannot be the best possible Being.
2) Cosmological (first cause) – everything finite has a cause, which itself has a cause, which itself had a cause, and so on. This chain cannot be infinite, so the first thing must not have a cause and therefore, must be God.
The world/universe is ‘contingent’ and logically possible not to exist and, even if it always existed, there is nothing to show why. As everything must have sufficient reason, it must be outside the universe and therefore it must be God.
3) Eternal truths – some statements are always true (e.g. 2 +2 = 4) As all truths are part of a mind, an eternal truth must be a part of an eternal mind, i.e. God
As there must be a reason for the contingent world, and this reason cannot be contingent but sought from eternal truths, a reason for what exists must exist, therefore external truths must, in some way, exist and can only exist as thoughts on the mind of God.
4) Pre-established harmony/design – everything in the world cannot have been created by chance and therefore was designed for a purpose by God
