All possible knowledge, then, depends on the validity of reasoning. If the feeling of certainty which we express by words like must be and therefore and since is a real perception of how things outside our own minds really ‘must’ be, well and good. But if this certainty is merely a feeling in our own minds and not a genuine insight into realities beyond them — if it merely represents the way our minds happen to work — then we can have no knowledge. Unless human reasoning is valid no science can be true.
It follows that no account of the universe can be true unless that account leaves it possible for our thinking to be a real insight. A theory which explained everything else in the whole universe but which made it impossible to believe that our thinking was valid, would be utterly out of court. For that theory would itself have been reached by thinking, and if thinking is not valid that theory would, of course, be itself demolished. It would have destroyed its own credentials. It would be an argument which proved that no argument was sound — a proof that there are no such things as proofs — which is nonsense.
A worldview is meant to give a systematic explanation of those inescapable, unavoidable facts of experience accessible to all people, in all cultures, across all periods of history. In biblical terms, those facts constitute general revelation. Philosophers sometimes refer to them collectively as the life-world, or lived experience, or pre-theoretical experience. The whole point of building theoretical systems is to explain what humans know by pre-theoretical experience. That is the starting point for any philosophy. That is the data it seeks to explain. If it fails to explain the data of experience, then it has failed the test. It has been falsified.
Charles Darwin in a letter to Henry Fawcett (Darwin & Seward, 1903), cited in Plant Microevolution and Conservation in Human-influenced Ecosystems (Cambridge University Press : Nov 26, 2009), p. 12.
About 30 years ago there was much talk that geologists ought to observe and not to theorize; and I well remember someone saying that at that rate a man might as well go into a gravel-pit and count the pebbles and describe the colours. How odd it is that anyone should not see that all observation must be for or against some view if it is to be of any service!
If you were looking for a place to assign blame for nosism — the use of the first-person plural to refer to oneself — you might start with God (“Let us make man in our image, after our likeness,” etc.) or with papal practice, or with Henry II, who is credited with having introduced the practice of English monarchs referring to themselves in the majestic plural in the 12th century; in the end, none of this is convincing. Without getting into the intricacies of theology and Hebrew grammar, for instance, it’s quite possible that God is a trinitarian, or using an intensifier to boast about His greatness in a way that seems more understandable coming from the creator of space and time than from a middle-tier magazine columnist, while popes and monarchs are not using the plural to refer to themselves alone but to themselves and God and/or the polities for which they speak, which may be arrogant, but displays a different sort of presumptuousness than that of a writer claiming to have divined the thoughts of everyone reading them. Even then, all of this is archaic: God hasn’t said anything in a long time, popes have generally passed over the “we” business since John Paul II, and even British monarchs aren’t all that likely to abuse the royal we.
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It is a matter of some importance and also a matter which falls properly within the province of philosophy, to discuss the question what sort of proof, if any, can be given of ‘the existence of things outside of us’. And to discuss this question was my object when I began to write the present lecture. But I may say at once that, as you will find, I have only, at most, succeeded in saying a very small part of what ought to be said about it.
Suppose one reads a story of filthy atrocities in the paper. Then suppose that something turns up suggesting that the story might not be quite true, or not quite so bad as it was made out. Is one’s first feeling, “Thank God, even they aren’t quite so bad as that”, or is it a feeling of disappointment, and even a determination to cling to the first story for the sheer pleasure of thinking your enemies are as bad as possible? If it is the second then it is, I am afraid, the first step in a process which, if followed to the end, will make us into devils. You see, one is beginning to wish that black was a little blacker. If we give that wish its head, later on we shall wish to see grey as black, and then to see white itself as black. Finally we shall insist on seeing everything — God and our friends and ourselves included — as bad, and not be able to stop doing it: we shall be fixed for ever in a universe of pure hatred.
Jean Paul Sartre, " trans., Philip Mairet, in Existentialism from Dostoevsky to Sartre, edited by Walter Kaufmann (World Publishing Company: 1956; Lecture on October 29, 1945, at the Club Maintenant in Paris), pp. -311.
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My purpose here is to offer a defence of existentialism against several reproaches that have been laid against it. ... Many may be surprised at the mention of humanism in this connection, but we shall try to see in what sense we understand it. In any case, we can begin by saying that existentialism, in our sense of the word, is a doctrine that does render human life possible; a doctrine, also, which affirms that every truth and every action imply both an environment and a human subjectivity.
It is a common saying that thought is free. A man can never be hindered from thinking whatever he chooses so long as he conceals what he thinks. The working of his mind is limited only by the bounds of his experience and the power of his imagination. But this natural liberty of private thinking is of little value. It is unsatisfactory and even painful to the thinker himself, if he is not permitted to communicate his thoughts to others, and it is obviously of no value to his neighbours. Moreover it is extremely difficult to hide thoughts that have any power over the mind. If a man’s thinking leads him to call in question ideas and customs which regulate the behaviour of those about him, to reject beliefs which they hold, to see better ways of life than those they follow, it is almost impossible for him, if he is convinced of the truth of his own reasoning, not to betray by silence, chance words, or general attitude that he is different from them and does not share their opinions. Some have preferred, like Socrates, some would prefer to-day, to face death rather than conceal their thoughts. Thus freedom of thought, in any valuable sense, includes freedom of speech.
The hallmark of the Enlightenment was “free thought,” that is, the pursuit of knowledge by means of unfettered human reason alone. While it’s by no means inevitable that such a pursuit must lead to non-Christian conclusions and while most of the original Enlightenment thinkers were themselves theists, it has been the overwhelming impact of the Enlightenment mentality that Western intellectuals do not consider theological knowledge to be possible. Theology is not a source of genuine knowledge and therefore is not a science (in German, a Wissenschaft). Reason and religion are thus at odds with each other. The deliverances of the physical sciences alone are taken as authoritative guides to our understanding of the world, and the confident assumption is that the picture of the world which emerges from the genuine sciences is a thoroughly naturalistic picture.
I think there’s just been a very basic shift in how we view our responsibility. We used to view our role as building tools for people and saying, “Hey, we’re going to put this power in your hands”. And we think people are basically good, and we think that that can have a net positive effect. Now I just think we understand — both because of the ability for us to develop these things and because of the scale at which we operate — that it’s also our responsibility to make sure that all these tools are used well, not just to put them in people’s hands.