George Berkeley ... is important in philosophy through his denial of the existence of matter—a denial which he supported by a number of ingenious arguments. He maintained that material objects only exist through being perceived. To the objection that, in that case, a tree, for instance, would cease to exist if no one was looking at it, he replied that God always perceives everything; if there were no God, what we take to be material objects would have a jerky life, suddenly leaping into being when we look at them; but as it is, owing to God’s perceptions, trees and rocks and stones have an existence as continuous as common sense supposes. This is, in his opinion, a weighty argument for the existence of God.
                                                          —Bertrand Russell, in A History of Western Philosophy (1945)


When discussing how Berkeley's philosophy appeared to be self-evidently false, but impossible to refute, Dr. Johnson kicked out at a nearby stone, exclaiming "I refute it thus!"

How utterly absurd. I could reiterate my point from last week that philosophers sometimes go to extreme ends when trying to hold on to a single idea and avoid the cognitive dissonance that arises from that, or I could elaborate on the point that after Descartes dualism was rejected by Spinoza's monism it was sort of inevitable that someone would come down on the side of "no, everything is immaterial," but it's a beautiful Friday and I am going outside to soak in the pleasures of the physical world that I find myself in and for which I've been evolved to enjoy. Let's therefore make this quick so we can turn our attention away from Berkeley and watch him disappear…

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George Berkeley (1685-1753 CE) was an Anglo-Irish philosopher whose primary achievement was the advancement of a theory he called "immaterialism," later referred to as "subjective idealism" by others.

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Needs to Adapt

Gone Extinct
Berkeley’s theory of immaterialism contends that individuals can only know directly sensations and ideas of objects, not abstractions such as "matter.” The theory also contends that ideas are dependent upon being perceived by minds for their very existence, a belief that became immortalized in the dictum, Esse est percipi - to be is to be perceived. Over a century later Berkeley's thought experiment was summarized in a limerick by Ronald Knox and an anonymous reply: There was a young man who said "God / Must find it exceedingly odd / To think that the tree / Should continue to be / When there's no one about in the quad." // "Dear Sir: Your astonishment's odd; / I am always about in the quad. / And that's why the tree / Will continue to be / Since observed by, Yours faithfully, God.” Well that was fun. Abstractions such as matter are categories. They are definitions we can use to group actual objects together in order to study and understand them better. We created and defined the abstractions. They do not exist in the physical sense of the word, but we can know them for what they are. Also, the physical universe happily went on before us and wouldn’t care if we went extinct.
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In Leibniz, a vast edifice of deduction is pyramided upon a pin-point of logical principle. In Leibniz, if the principle is completely true and the deductions are entirely valid, all is well; but the structure is unstable, and the slightest flaw anywhere brings it down in ruins.
     —Bertrand Russell, A History of Western Philosophy (1945) p. 644.

Take a look at that picture and see if you can't guess where the flaw was in Gottfried Leibniz's vast edifice of deduction... Last week I profiled Isaac Newton, one of the most gifted scientists in history who secretly wrote more about theology and and alchemy than he did about gravity, optics, and calculus combined. Sadly we're in for a repeat of a similar story here. Leibniz had a beautifully ordered mind that is credited with independently inventing calculus at the same time as Newton. He also made important discoveries in physics and technology. And while those contributions remain intact and ensure Leibniz a prominent place in history, his vast writings are littered with a philosophy that is as consistent as one would expect from a formidable mathematician and logician, but is undermined by his stubborn insistence on building it around an unproven entity.

In psychology, the term cognitive dissonance is used to describe "the excessive mental stress and discomfort experienced by an individual who holds two or more contradictory beliefs, ideas, or values at the same time. This stress and discomfort may also arise within an individual who holds a belief and performs a contradictory action or reaction. For example, an individual is likely to experience dissonance if they are addicted to smoking cigarettes and continue to smoke despite knowing how seriously it jeopardizes health. Stress and discomfort increase in proportion to the importance of the beliefs, ideas or values that are contradicted." And while Aristotle said that "It is the mark of an educated mind to be able to entertain a thought without accepting it," it's important to note that educated person is merely entertaining the thought, not clutching it tightly. Many people live their lives holding on to unexamined thoughts, and this causes great stress in their minds. Are you one of them? Try this Philosophical Health Check to see what kinds of contradictions might underlie some of your own beliefs. It's just a 5 minute test comprising 30 agree/disagree questions. Go on. Give yourself a checkup.

Finished? How'd you do? The test designers told me I had one contradiction in my beliefs, but that this contradiction could be cleared up if I had a good argument for it. Well, I do. So I consider myself to be tension free. Hooray! Whether or not this test is perfectly designed, I did like its explanation of what cognitive dissonance might feel like. Did you catch that description at the end of the test?

It may help to think of the idea of 'tension' in terms of an intellectual balancing act. Where there is little or no tension between two beliefs, no particular intellectual effort is required to balance them. But where there is a lot of tension, either one has to "jump off the highwire" by abandoning one belief; keep one's balance by intellectual effort and dexterity; or else "fall off the highwire" by failing to deal with the tension.

So I suppose I'm avoiding cognitive dissonance through a little "intellectual effort and dexterity," but that is nothing compared to the work that Leibniz went through to avoid jumping off the highwire and abandoning his belief in one of the central tenets of Christianity—that God is all good, all wise, and all powerful. In the opening passages of Leibniz's Discourse on Metaphysics, he presented the following tenets as his theological stake in the ground:

“God is an absolutely perfect being”; “power and knowledge are perfections, and, insofar as they belong to God, they do not have limits”; “Whence it follows that God, possessing supreme and infinite wisdom, acts in the most perfect manner, not only metaphysically, but also morally speaking…”

This is not a departure from anything the Christian church has taught for two thousand years, but Leibniz tried desperately to square this belief with the world as it is and somehow account for the evil we find in it. Leibniz asserted that "the truths of theology and philosophy cannot contradict each other, since reason and faith are both 'gifts of God' so that their conflict would imply God contending against himself." He therefore reasoned:

I do not believe that a world without evil, preferable in order to ours, is possible; otherwise it would have been preferred. It is necessary to believe that the mixture of evil has produced the greatest possible good: otherwise the evil would not have been permitted.

Yuck. Talk to any number of victims of evil in history and see if they thought their suffering was necessary to produce all the good we have in this world. Talk to anyone with a utopian vision and see if they can't easily conceive of a world with far greater good in it. Leibniz was either fantastically unimaginative, unspeakably callous, or just irrationally determined to somehow do more than simply entertain his conflicting ideas. Despite being known as "the last universal genius," a man who perhaps "read as much, studied as much, meditated more, and wrote more" than any other man, someone who was tutored by Huygens, given access to unpublished manuscripts of Descartes and Pascal, spoke with Spinoza about the masterpiece Ethics that he was working on, and exchanged letters with over 1100 different people across Europe over the course of his life, Leibniz—despite all of this—shoehorned every bit of it into his religious worldview. He stands as a monument to the importance of questioning all of your beliefs as you build up the philosophy by which you live. Let's look quickly at the rest of what Leibniz constructed as I evaluated him in my survival of the fittest philosophers.

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Gottfried Leibniz (1646-1716 CE) was a German philosopher, polymath, and mathematician. He invented infinitesimal calculus independently of Newton, and his notation has been in general use since then. He also invented the binary system, the foundation of virtually all modern computer architectures. Leibniz invoked seven fundamental philosophical principles.

Survives
1) Identity/contradiction. If a proposition is true, then its negation is false and vice versa. Basic logic.

3) Sufficient reason. "There must be a sufficient reason for anything to exist, for any event to occur, for any truth to obtain.” Yes. Nothing happens spontaneously or supernaturally.

Needs to Adapt
2) Identity of indiscernibles. Two things are identical if and only if they share the same and only the same properties. This is frequently invoked in modern logic and philosophy. The "identity of indiscernibles" is often referred to as Leibniz's Law. It has attracted the most controversy and criticism, especially from corpuscular philosophy and quantum mechanics. This is either a circular tautology or incorrect depending on how it is interpreted.

Gone Extinct
4) Pre-established harmony. "The appropriate nature of each substance brings it about that what happens to one corresponds to what happens to all the others, without, however, their acting upon one another directly.” A dropped glass shatters because it "knows" it has hit the ground, and not because the impact with the ground "compels" the glass to split. Every "substance" only affects itself, but all the substances (both bodies and minds) in the world nevertheless seem to causally interact with each other because they have been programmed by God in advance to "harmonize" with each other. Complete bunk. Where would this harmony reside in an object? The standard worldview of cause and effect is much more compelling and useful.

5) Law of Continuity. Natura non saltum facit - nature makes no leap. The principle expresses the idea that natural things and properties change gradually, rather than suddenly. This is merely a matter of definition of what is gradual and what is sudden. Mutations and chemical reactions cause changes that occur in nanoseconds.

6) Optimism. "God assuredly always chooses the best.” Our universe is, in a restricted sense, the best possible one God could have made. Note that the word optimism here is used in the classic sense of optimal, not in the mood-related sense, as being positively hopeful. If that is true, then given the inefficiencies, pain, and suffering we see in nature, god surely is not the most supreme being there could be, so therefore he must not be god. Reverse ontological argument!

7) Plenitude. Leibniz believed that the best of all possible worlds would actualize every genuine possibility, and argued that this best of all possible worlds will contain all possibilities, with our finite experience of eternity giving no reason to dispute nature's perfection. There are plenty of reasons to dispute nature’s perfection. What an excellent mathematician. What a silly philosopher.
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One of my readers let me know that he objected to the use of the word "silly" to describe Leibniz. Certainly he was an earnest man who possessed powerful skills of reason and contributed much to the progress of human knowledge, so I conceded I'd been a bit harsh in applying that term to Leibniz. But rereading some of the lesser definitions of the word now, I came across this one:

silly - (adjective) used to convey that an activity or process has been engaged in to such a degree that someone is no longer capable of thinking or acting sensibly, e.g. "he often drank himself silly"

While he may not have been a silly philosopher, I think I can stand by the judgment that Leibniz philosophised himself silly. I hope I ain't doin' the same...

Nature and Nature's laws lay hid in night:
God said, Let Newton be! — and all was light.
-- Alexander Pope, in lines written for Newton's monument in Westminster Abbey

I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me. 
— From the memoirs of Isaac Newton

A few weeks ago, I profiled Galileo in an essay titled, When Science Began to Drive Philosophy. I should have added "Again" to the end of that title since Aristotle was undoubtedly a philosopher driven by his scientific inquiries, but I never promised perfection in these posts—just a willingness to expose ideas in the hopes they will get corrected and refined. Thanks to everyone who points those mistakes out to me. Well, we've moved forward another 100 years through the scientific revolution and come to the big bang at the end of that struggle--Isaac Newton, whose Laws of Motion, Calculus, and Optics, cracked open many mysteries of the universe and "unwove the rainbow," as Keats once said. Not being a philosopher, Newton doesn't elicit much comment in my analysis of the survival of the fittest philosophers, but seeing as how he is still regarded as the #1 or #2 most influential scientist of all time, he deserves a mention for the way he changed the world's cosmology and metaphysics and thus helps us put the ideas of other philosophers into perspective by considering the knowledge of the universe that was available to them at the time.

Speaking of having knowledge available and correcting mistakes when they are made… One of the most prominent scientists of the present day, Neil deGrasse Tyson, recently disparaged the field of philosophy in a podcast interview. After he and his interviewers took easy shots at some of the inane questioning that goes on in the field (as if every field isn't similarly littered with inanities), Massimo Pigliucci, a friend of Tyson's as well as a holder of PhDs in Evolutionary Biology AND Philosopy, stepped in and offered a spirited defence of the value of philosophy. Both men mentioned Isaac Newton in their remarks, so I thought it would be worth noting those segments as relevant to this essay, and to the struggle that always goes on between the empirical worlds of science and philosophy, and the speculative worlds of philosophy and religion. Let's hear the remarks. First, the partially justified criticism from Tyson:

"But philosophy has basically parted ways from the frontier of the physical sciences, when there was a day when they were one and the same. Isaac Newton was a natural philosopher, the word physicist didn’t even exist in any important way back then. So, I’m disappointed because there is a lot of brainpower there, that might have otherwise contributed mightily, but today simply does not."

But now, the clear correction from Pigliucci:

"Finally, Neil, please have some respect for your mother. I don’t mean your biological one (though that too, of course!), I am referring to the intellectual mother of all science, i.e., philosophy. As you yourself seem to have a dim perception of (see your example of Newton), one of the roles of philosophy over the past two and half millennia has been to prepare the ground for the birth and eventual intellectual independence of a number of scientific disciplines. But contra what you seem to think, this hasn’t stopped with the Scientific Revolution, or with the advent of quantum mechanics. Physics became independent with Galileo and Newton (so much so that the latter actually inspired David Hume and Immanuel Kant to do something akin to natural philosophizing in ethics and metaphysics), biology awaited Darwin (whose mentor, William Whewell, was a prominent philosopher, and the guy who coined the term “scientist,” in analogy to artist, of all things); psychology spun out of its philosophical cocoon thanks to William James, as recently (by the standards of the history of philosophy) as the late 19th century. Linguistics followed through a few decades later (ask Chomsky); and cognitive science is still deeply entwined with philosophy of mind (see any book by Daniel Dennett). Do you see a pattern of, ahem, progress there?"

Pigliucci makes a beautiful point here. Sometimes the nebulous questions of philosophy coalesce to give birth to a science, just as the stellar clouds of nebulas act as nurseries to the birth of stars. You'd think that would be a point that would stick with Tyson the astrophysicist…

But back to Newton, the scientist star that brought us here to begin with. Here are two of his best quotes before I note his brief mention in my fittest philosophers series.

Plato is my friend, Aristotle is my friend, but my greatest friend is truth.

 If I have seen further, it is by standing on the shoulders of giants.

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Isaac Newton (1642-1727 CE) was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been considered by many to be the greatest and most influential scientist who ever lived.

Survives
Newton described universal gravitation and the three laws of motion, which dominated the scientific view of the physical universe for the next three centuries. Newton showed that the motions of objects on Earth and of celestial bodies are governed by the same set of natural laws, by demonstrating the consistency between Kepler’s laws of planetary motion and his theory of gravitation, thus removing the last doubts about heliocentrism and advancing the Scientific Revolution. Just a brief note to acknowledge the debt our view of the universe owes to the breakthroughs that Newton published.

Needs to Adapt

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Newton was also highly religious. He was an unorthodox Christian, and wrote more on Biblical hermeneutics and occult studies than on science and mathematics, the subjects he is mainly associated with. What a shame a mind like his wasted this much time on religious ideas that had no impact.
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Talk about the harm of religion. Even if it never led to irrational conflict and terrorism and war, the opportunity cost of lives spent idly speculating on unknowable realms and unproven actors in the sky is an immense loss to the progress of humanity. Look through the wikiquote page from Isaac Newton and despair at the quantity of nonsense he wrote about his God and religion.

In default of any other proof, the thumb would convince me of the existence of a God.

Can it be by accident that all birds beasts & men have their right side & left side alike shaped (except in their bowels) & just two eyes & no more on either side the face & just two ears on either side the head & a nose with two holes & no more between the eyes & one mouth under the nose & either two fore leggs or two wings or two arms on the sholders & two leggs on the hipps one on either side & no more? Whence arises this uniformity in all their outward shapes but from the counsel & contrivance of an Author?

But as John Maynard Keynes said about him in an address to the Royal Society:

Newton was not the first of the age of reason. He was the last of the magicians, the last of the Babylonians and Sumerians, the last great mind that looked out on the visible and intellectual world with the same eyes as those who began to build our intellectual inheritance rather less than 10,000 years ago.

He wasn't exactly the last believer in magic (as we shall see), but we should not yet condemn history's thinkers who were held under the sway of a religious outlook. The door to our cosmological understanding of our universe was just now being unlocked by Newton's keys, though he himself never entered that previously darkened room. I understand the draw of a mystery box though, and there is no doubt we have created an endless one with our religions, so it's probably no coincidence that Newton, drawn to explore the mysteries of the natural world, was also drawn to explore the mystery of the spiritual realm. In one of the latest episodes of Cosmos, Neil deGrasse Tyson tells the story of Michael Faraday, the scientist who uncovered secrets of electromagnetism and invented the first electric motor, and how he was utterly entranced by the mysteries that science spread before him. For me, philosophy held the same sense of an unknown just waiting to be found—particularly the mystery of morality and what, if anything, lies at the base of all our ethical systems. Since the first edicts of religion were questioned by Socrates in the Dilemma of Euthyphro, philosophers have gathered facts about these mysterious moral passions we feel in the hopes of explaining them and making sense of them. What will be the next science to be spun off from philosophy? My bet is the moral sciences, once an explanation of the objective basis for morality is discovered and accepted. I say that basis is the long-term survival of life (which I have used in my response to the Sam Harris Moral Landscape Challenge and am using in an article I'm writing on the Is-Ought divide at the moment that I hope will be accepted by Massimo Pigliucci for his Scientia Salon), but really, we don't know yet. And isn't that exciting? To think that an ethical revolution or some other new science may lie just around the corner for humanity and that we will get to live through it? That sure makes me want to keep spending my brainpower here.

It's been a rough few years for America in its role as a "world leader." As any basic text on leadership will tell you though, your words better be backed up by your actions or your followers will notice. And while the U.S. was founded on wise words as a place of "life, liberty, and the pursuit of happiness" with a government "of the people, by the people, for the people," and especially for the "tired, poor, huddled masses yearning to breathe free," it has become characterised of late by its use of torture, rising inequality, combination of church and state, and a government and media that are dominated by large corporations and wealthy individuals. I could continue to go on about the true purpose of government and what America needs to do to reassert its position as a thought leader, but I'll save that for another time and instead continue building my catalogue of the fittest philosophers by profiling the man who inspired Thomas Jefferson's turn of phrase in the Declaration of Independence--John Locke.

Locke, the son of a country lawyer, born in 1632, grew up in "one of the most extraordinary centuries of English political and intellectual history." He lived to see battles between the Crown and Parliament overlapping with conflicts between Protestants, Anglicans, and Catholics, which all swirled into civil war in the 1640s. Once the reigning king Charles I was defeated (and beheaded), England tried a great experiment in government by abolishing the monarchy, the House of Lords, and the Anglican church while it established a Protectorate under Oliver Cromwell in the 1650s. When the Protectorate collapsed after the death of Cromwell, Charles II was restored to the throne and the House of Lords and the Anglican Church were reinstituted. This return to the past (which lasted from 1660-1685) was far from peaceful though and was "marked by continued conflicts between King and Parliament, and debates over religious toleration for Protestant dissenters and Catholics." Finally, after three years under the reign of the Scottish Catholic King James II, England had its Glorious Revolution in 1688 when James II was driven from England and replaced by William of Orange and his wife Mary. This was a major turning point in English history as it marked the time when the balance of power in the English government passed from the King to the Parliament.

Tumultuous times indeed. And Locke was not just a witness to the history of these events. He was on board the royal yacht from Holland accompanying Princess Mary in 1688 to reunite with her conquering husband. Locke's thoughts were a major influence on the Bill of Rights of 1689—a formal parliamentary restatement of the invitation that had been extended to William and Mary to become joint sovereigns of England. This Bill of Rights was one of the most important documents in the political history of Britain, and was an influential predecessor of the French Declaration of the Rights of Man and of the Citizen (1789), the United States Bill of Rights (1791), the United Nations Universal Declaration of Human Rights (1948), and the European Convention on Human Rights (1953). The Bill laid out certain basic rights for all Englishmen and quickly became popular nationwide. The Act stated that there should be:

• no royal interference with the law.
• no taxation by Royal Prerogative.
• freedom to petition the monarch without fear of retribution.
• no standing army during a time of peace without the consent of parliament.
• no royal interference in the freedom of the people to have arms for their own defence as suitable to their class and as allowed by law.
• no royal interference in the election of members of Parliament.
• the freedom of speech and debates.
• no excessive bail or "cruel and unusual" punishments.

Never again was the monarchy to establish primacy in the United Kingdom (a name looking more and more anachronistic all the time). As a philosopher who loves to see good thoughts put into action by the people of a nation, I wondered how it was that Locke first put his thoughts together and then achieved such sway with them. I suppose it was inevitable that centuries of off-and-on fighting among monarchs over religion would eventually lead to the thought that we might be better off without either of those factions in control. And Locke was lucky enough (and brave enough and diligent enough) to be there with those thoughts when the right forces came together to change history without him having to lose his head over the matter.

Educated at Oxford, Locke had a long and fortuitous career there. He received his B.A. in 1656 and his Master of Arts in 1658. He was elected as a Lecturer in Greek in 1660, and a Lecturer in Rhetoric in 1663. Shortly after this, Locke needed to make a decision about what to study if he wanted to remain ensconced in this scholarly community. Fifty-five positions were available for future clergymen, two for law, two for medicine, and one for moral philosophy. The easy way forward would have been to study religion, but Locke chose to be a doctor. This somewhat random and difficult choice (as so many we make in our own formative years are) would turn out to be very fortunate. The new leader of the Oxford scientific group was Robert Boyle (he of Boyle's Law about the relationship between pressure and volume in gases, as well as one of the founding members of the English Royal Society when it was established in 1660). Boyle became Locke's scientific mentor and taught him about atomism, a perspective which made him critical of elements in Descartes' philosophy. Through his studies in medicine, Locke continued his involvement with the earth-shattering scientific movement that was going on at the time. He would later read a paper by his fellow Royal Society member Isaac Newton titled Principia Mathematica Philosophiae Naturalis, and even consult with Christiaan Huygens as to the soundness of its mathematics.

Keeping at the forefront of science and philosophy was an important precursor to Locke's success, but it was a chance meeting that thrust his expertise into the heart of the action that was taking place. In 1666, Locke was running a laboratory / pharmacy with a friend, when Lord Ashley of Shaftesbury, one of the richest men in England, came to Oxford to drink the medicinal waters there. Lord Ashley had asked Locke's partner to provide these waters, but as he had to be out of town, the friend asked Locke to deliver the waters instead. Locke and Ashley met, liked one another, and "as a result of this encounter, Ashley invited Locke to come to London as his personal physician. In 1667 Locke did move to London becoming not only Lord Ashley's personal physician, but secretary, researcher, political operative and friend. Living with him, Locke found himself at the very heart of English politics in the 1670s and 1680s." Among Ashley's commercial projects was an effort to found colonies in the Carolinas, and so Locke was involved in the writing of the fundamental constitution of the Carolinas—surely a formative piece of practice as well as a chance to burnish his credentials and reputation. Shaftesbury, as a founder of the Whig movement, exerted great influence on Locke's political ideas and when Shaftesbury became Lord Chancellor in 1672, Locke became further immersed in the politics of the realm. As we know though, the politics of that day were filled with intrigue and massive, swift, reversals of fortune. Shaftesbury came in and out of favour. Locke had to go in and out of exile to both France and Holland (where there were alternating periods of religious wars and toleration as well). Over two decades, one of the brightest minds of his time was kept on the run learning about different forms of government and encountering scientific advancements that overturned the cosmology of both of the Churches that were at war with one another. While in exile, Locke finished An Essay Concerning Human Understanding and became closely associated with other English revolutionaries in exile. English intelligence services infiltrated the rebel group in Holland and thwarted their efforts for a while, but ultimately, the rebels were successful in their Glorious Revolution when King James II alienated most of his supporters and William of Orange was invited to bring a Dutch force to England. The Dutch Republic had been founded as a secular state to allow for religious differences, and this was obviously what England needed more of. What heady times it must have been for Locke to return to his birth nation with the chance to take part in rewriting its government. What a string of lucky breaks it was to put him in that position, when any number of them could have gone horribly wrong.

After his return from exile, Locke published his Two Treatises of Government and it was a truly revolutionary piece of work. The First Treatise aimed at refuting the Divine Right of Kings. The Second Treatise provided Locke's positive theory of government—an account that involved several ideas common at the time including natural rights theory and the social contract. Europeans had long had encounters with the natives of North America by this time, which set them thinking often and hard about the "state of nature" and the reason societies progressed or not. Locke argued in his Two Treatises of Government that "political society existed for the sake of protecting property, which he defined as a person's life, liberty, and estate." He argued that people have such rights independent of the laws of any particular society. Coming from where he did, losing his own possessions time and time again, and seeing nations of men around him losing the same and more, it's no wonder Locke came up with these ideas and found them gladly accepted. Before we evaluate them in the light of today's understanding though, let's hear some more direct words from Locke himself.

Reading furnishes the mind only with materials of knowledge; it is thinking that makes what we read ours.

New opinions are always suspected, and usually opposed, without any other reason but because they are not already common.

It is one thing to show a man that he is in error, and another to put him in possession of the truth.

Those who have not thoroughly examined to the bottom all their own tenets, must confess they are unfit to prescribe to others; and are unreasonable in imposing that as truth on other men's belief, which they themselves have not searched into, nor weighed the arguments of probability, on which they should receive or reject it.

Religion, which should most distinguish us from the beasts, and ought most particularly elevate us, as rational creatures, above brutes, is that wherein men often appear most irrational, and more senseless than beasts.

He that would seriously set upon the search of truth, ought in the first place to prepare his mind with a love of it. For he that loves it not, will not take much pains to get it; nor be much concerned when he misses it.

One unerring mark of the love of truth is not entertaining any proposition with greater assurance than the proofs it is built upon will warrant.

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John Locke (1632-1704 CE) was an English physician and philosopher regarded as one of the most influential of Enlightenment thinkers. Considered the first of the British empiricists, he is equally important to social contract theory. His work had a great impact upon the development of epistemology and political philosophy. His contributions to classical republicanism and liberal theory are reflected in the American Declaration of Independence.

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Needs to Adapt
Locke's theory of mind is often cited as the origin of modern conceptions of identity and the self. He was the first to define the self through a continuity of consciousness. Locke defines the self as "that conscious thinking thing, (whatever substance, made up of whether spiritual, or material, simple, or compounded, it matters not) which is sensible, or conscious of pleasure and pain, capable of happiness or misery, and so is concerned for itself, as far as that consciousness extends.” He does not, however, ignore "substance," writing that "the body too goes to the making of the man.” The Lockean self is therefore a self-aware and self-reflective consciousness that is fixed in a body. Destruction of the body in the form of Alzheimer’s, amnesia, or stroke, leads one to lose that continuity of consciousness by the self. That doesn’t change the identity of the individual. Identity is therefore independent from consciousness. Identity lies at the Mind x Body intersection. One helpful analogy is to say identity is like a river. Not the water that flows through it, but the channel that actually forms the river. When storms occur and water is high, the river is deepened. When drought occurs, the river slows and silts up. When earthquakes or glaciers reshape the landscape, the riverbed may hold no water at all. If we know the events that carved the river, we can recognize its identity no matter what state it is in. Likewise, we can recognize identity when we know the events that shaped it. If you know the river and are told the volume of water that will flow its way, you know what the river will look like. If you know a person and are told the events that will occur to them, you will recognize how they handle it. This is how we know people after long absences, and this is how changes during brief separations can surprise us.

Locke's political theory was founded on social contract theory. Unlike Thomas Hobbes, Locke believed that human nature is characterized by reason and tolerance. In a natural state all people were equal and independent, and everyone had a natural right to defend his “Life, health, Liberty, or Possessions.” This was the basis for the phrase in America, "Life, liberty, and the pursuit of happiness.” There are no rights in the natural state - nature is harsh and takes what it can. It is competition within evolutionary systems that causes everyone to defend their life, health, liberty, and possessions. If they did not, they would not survive. Rights only come from the state, which are granted in return for recognizing the benefits of social cooperation. In a natural state, humans were hierarchical and fought to establish dominance and subservience, but we have learned that it is more efficient to cooperate and not to fight to maintain hierarchies.

Locke argued that property is a natural right and it is derived from labor. Labor creates property, but it also does contain limits to its accumulation: man’s capacity to produce and man’s capacity to consume. According to Locke, unused property is waste and an offense against nature, although money makes possible the unlimited accumulation of property without causing waste through spoilage. Again, only the state can grant rights. Nature grants no right to property no matter how much labor has been put into it. Ask bees or beavers. Notice that humans also feel the “right” to property even when they have not worked at all for it - as in inheritance. Waste and inefficiency are missed opportunities to live better and stave off extinction. Money has made possible the creation of inequality exponentially greater than in the natural state. These levels of inequality are grave threats to the ethics of social cooperation.

Gone Extinct
Locke postulated that the mind was a blank slate or tabula rasa. Contrary to pre-existing Cartesian philosophy, he maintained that we are born without innate ideas, and that knowledge is instead determined only by experience derived from sense perception. Recent experiments with infants have revealed that they come “pre-wired” with some emotional and learning capabilities. This is more evidence that it is not nature or nurture, but nature x nurture. It is more evidence for the middle way.
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Not bad for creating a political philosophy without the benefit of hundreds of years of democracy that we now have. Seeing the difficulties that America has run into after all this time, one can't help but wonder if it will adapt and survive, or suffer some overthrow and be replaced by newer, better ideas. I'd like to think we can change things smoothly and without unnecessary upheaval, but part of me would love to be around, like Locke, for a more revolutionary change.

he generally accepted Descartes's physics, Spinoza rejected Cartesian metaphysics, objecting in particular to the conception of the mind as a "mental substance" radically distinct from matter. To Spinoza, there would be no way for these things to interact if they were in fact entirely separate. Monism—a universe of only one substance—was the only logical conclusion.

Just what was this one substance? The world would have to wait until after Spinoza's death to find out, for times were tough for freethinkers in the 17th century. In 1656, seven years even before RD'sPoP was published, Spinoza had already been issued "the harshest writ of herem, or excommunication, ever pronounced by the Sephardic community of Amsterdam. It was never rescinded, and we do not know for certain what Spinoza's 'monstrous deeds' and 'abominable heresies' were alleged to have been, but an educated guess comes quite easy. No doubt he was giving utterance to just those ideas that would soon appear in his philosophical treatises." Prior to being excommunicated, Spinoza had been "questioned by two members of his synagogue about the nature of God, and Spinoza apparently responded that God has a body and nothing in scripture says otherwise. He was later attacked on the steps of the synagogue by a knife-wielding assailant shouting 'Heretic!' He was apparently quite shaken by this attack and for years kept (and wore) his torn cloak, unmended, as a souvenir." Spinoza, therefore, was understandably secretive about his continued work. (He reportedly wore a signet ring to mark his letters, which was engraved with a rose and the word "caute", Latin for "cautiously.") And yet, when he saw the principles of toleration in Holland being threatened by reactionary forces, he put aside work on his masterpiece Ethics, to anonymously publish Theologico-Political Treatise in 1670 in which he "put forth his most systematic critique of Judaism, and all organized religion in general,"  concluding that "the civil authorities should suppress Judaism as harmful to the Jews themselves." When the public reactions to this book were extremely unfavourable, Spinoza decided to refrain from publishing any more of his works. When he died just seven years later in 1677, he was still writing his Political Treatise, which was soon edited and published by his friends, along with Ethics and a few other unpublished writings.

And so, with Spinoza safely locked away in his tomb, the world finally got to hear his most influential thoughts. To begin, Spinoza presented the basic elements of his picture of God in Ethics, since that was the one thing that he believed united Descartes's two worlds. God, to Spinoza, was "the infinite, necessarily existing (that is, uncaused), unique substance of the universe. There is only one substance in the universe; it is God; and everything else that is, is in God." In case that wasn't clear, Spinoza's definition is neatly summarised with the use of one synonym that occurs in the Latin edition of Ethics, where he said Deus, sive Natura. God, or Nature. In context, Spinoza used the synonym this way: “That eternal and infinite being we call God, or Nature, acts from the same necessity from which he exists." Spinoza could be understood as trying to either make nature divine or make God natural, but there is no mistaking Spinoza's intention to redefine "God" in such a way as to take out all of the supernatural elements that other men had put into that word. Once he had gone that far, I say why bother using the term God at all? But look at the trouble Spinoza got into for going as far as he did, and we understand. We also appreciate the following quotes a little more warmly, even as we are about to coldly evaluate the rest of Spinoza's thoughts for their survival among the fittest philosophers.

Schisms do not originate in a love of truth, which is a source of courtesy and gentleness, but rather in an inordinate desire for supremacy.

I believe that if a triangle could speak, it would say that God is eminently triangular, while a circle would say that the divine nature is eminently circular. Thus each would ascribe to God its own attributes, would assume itself to be like God, and look on everything else as ill-shaped.

In practical life we are compelled to follow what is most probable; in speculative thought we are compelled to follow truth. We must take care not to admit as true anything which is only probable. For when one falsity has been let in, infinite others follow.

Of all the things that are beyond my power, I value nothing more highly than to be allowed the honor of entering into bonds of friendship with people who sincerely love truth.

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Baruch Spinoza (1632-1677 CE) was a Dutch Jewish philosopher considered one of the great rationalists of 17th-century philosophy, laying the groundwork for the 18th century Enlightenment and modern biblical criticism. His magnum opus, the posthumous Ethics, in which he opposed Descartes’ mind–body dualism, has earned him recognition as one of Western philosophy’s most important contributors.

Survives
Spinoza opposed Descartes' mind–body dualism. He contended that everything that exists in Nature (i.e., everything in the Universe) is one Reality (substance) and there is only one set of rules governing the whole of the reality that surrounds us and of which we are part. Yes. Everything has evolved within this universe. Nothing has come from outside of it.

Animals can be used in any way by people for the benefit of the human race, according to a rational consideration of the benefit as well as the animal’s status in nature. This sounds wrong to many modern ears, but key to its survival is the requirement to conduct a rational consideration of benefits. Just as humans must cooperate with each other to survive, we must cooperate with other animals to survive as well. Conservation is one form of cooperation. Husbandry can also be mutually beneficial to species - especially where we have created domestic species that willingly live in homes and on farms. Enslavement of animals is detrimental to their well-being, and through the poisons of stress and disease, and diet-induced obesity, to our health as well. Scientific experimentation on captive animals is rarely beneficial enough to compensate for the way it undermines the ethic of cooperation that must constantly be upheld to be truly meaningful.

Needs to Adapt
Spinoza's philosophy has much in common with Stoicism in as much as both philosophies sought to fulfill a therapeutic role by instructing people how to attain happiness. However, Spinoza differed sharply from the Stoics in one important respect: he utterly rejected their contention that reason could defeat emotion. On the contrary, he contended, an emotion can only be displaced or overcome by a stronger emotion. When used properly, reason can direct the emotions. Better cognitive appraisals help us replace negative emotions with positive emotions - no matter how strong they are. The strongest emotion is the joy of being alive. In that sense, Spinoza is correct. Reason helps us discover which actions lead to this ultimate emotion, and it can use that emotion as motivation for actions that require sacrifice and the endurance of unpleasant emotions in the short-term.

Good and evil are related to human pleasure and pain. Spinoza held good and evil to be relative concepts, claiming that nothing is intrinsically good or bad except relative to a particular individual. What is good is what ensures survival. What is evil is what brings extinction. We have evolved to feel pleasure for survival and pain for extinction. We use reason to recognize and avoid short-term pleasures that cause long-term pain. Judgment of the balance that must be achieved is sometimes difficult or even impossible to know ahead of time. In this sense, present choices between good and bad must be judged with probability under relative circumstances. After the fact though, judgments of good and evil are not relative to particular individuals. They are known objectively.

All rights are derived from the State. (Rights are legal, social, or ethical principles of freedom or entitlement; that is, rights are the fundamental normative rules about what is allowed of people or owed to people, according to some legal system, social convention, or ethical theory.) This is true by definition. But the State must recognize its purpose in aiding society to survive. Where it does, the rights it grants will be just. Where it does not, the restrictions it creates are wrong.

Gone Extinct
Spinoza was a thoroughgoing determinist who held that absolutely everything that happens occurs through the operation of necessity. For him, even human behavior is fully determined, with freedom being our capacity to know we are determined and to understand why we act as we do. He wrote: "men are conscious of their own desire, but are ignorant of the causes whereby that desire has been determined.” Extreme versions of free will and determinism are just that - extreme. The truth lies in the middle and is easier to understand when timescales are introduced. In the short-term, on biological timescales such as those concerning biochemistry, molecular biology, and cellular biology, events are determined by their current states. In the medium-term, on biological timescales such as those concerning organismic biology, and sociobiology, free will is not only possible, it determines the states that arise in the short-term and the long-term. In the long-term, on biological timescales such as those concerning ecology and evolutionary biology, the characteristics of competitiveness, cooperativeness, and adaptability are required for survival. In that sense, the long-term is determined. The free will that occurs in the medium-term, and the randomness of destructive cosmological events, means that who survives is unknown. Evolution is blind. We are not.

Spinoza believed that God exists but is abstract and impersonal. Everything done by humans and other animals is excellent and divine. In the universe, anything that happens comes from the essential nature of objects, or of God/Nature. According to Spinoza, reality is perfection. Reality is harsh. There is nothing divine about the history of extinction in the universe. We must do what we need to do to survive.
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Spinoza built his entire philosophy off his grounded view of a natural universe, but I didn't mention Spinoza's political thoughts, which were the rational result of the rest of his philosophical groundwork. They presented a passionate defence of the need for freedom, best summed up in this quote from Theological-Political Treatise:

The ultimate aim of government is not to rule, or restrain, by fear, nor to exact obedience, but, contrariwise, to free every man from fear, that he may live in all possible security; in other words, to strengthen his natural right to exist and work without injury to himself or others. No, the object of government is not to change men from rational beings into beasts or puppets, but to enable them to develop their minds and bodies in security, and to employ their reason unshackled; neither showing hatred, anger, or deceit, nor watched with the eyes of jealousy and injustice. In fact, the true aim of government is liberty.

This isn't the Tea Party's view of liberty from any rules at all—anarchy weakens our "natural right to exist." It is instead a view of liberty to become all that we can be, while living in a world where we can think what we need to think. (Spinoza's quote was, after all, from his final chapter titled "That In a Free State Every Man May Think What He Likes, and Say What He Thinks.") Coming from a man whose curtailed liberties surely stopped the world from gaining something even more valuable than he already offered it—this is particularly meaningful. For me, someone who freely publishes subversive philosophical thoughts—this liberty that Spinoza called for is vital. I strongly believe that an evolutionary philosophy can only improve through a process analogous to the natural selection of organisms—namely that the competition, cooperation, survival, merger, or extinction of ideas are all required to lead those ideas towards their fitness for purpose—so I don't take my liberty for granted and I cherish the opportunity I have to grow these ideas in my own lifetime, without fear of being made extinct myself. Thanks to all of you for helping with all of this as well.