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96

Neither Harris nor Hitchens dismiss or ridicule non-empirical philosophy itself. Harris, in particular, calls himself a philosopher and studies Eastern religions and similar traditions. What they ridicule, and rightly so, are the many attempts by philosophy and religion to make pronouncements about the physical world based on their non-empirical philosophy. ...


56

"p is false" implies "p is not true", but not vice verse because p can also be nonsense. "2 + 2 = 5" is both false and not true. "2 + 2 > red" is neither true nor false because it is nonsense. If it were false, its negation "2 + 2 ≤ red" would be true, which is not the case. Source An Inquiry Into Meaning and Truth


46

First, because they are "inconsequential". Nothing hangs on it for you, there is no need to act on them and accept the consequences also, it is a "cheap", easily swayable "acceptance". But this still leaves the question as to why accept rather than reject, as easily, perhaps at random. Which brings us to the second because: they are not accepted without ...


35

Ill formed question. Mathematics (specifically, logics) define what truth is. You are trying to test the validity of the tool with the tool itself. The answer would be a plain "yes". Otherwise (if you discuss mathematics as an issue of perception) you fall into Rusi's answer. Yes, you can have i apples, if you define the domain of i (i is not just a ...


33

Various candidates would be: self-referential sentences such as "This sentence is false." opinion-based sentences such as "Chocolate is the most delicious ice cream flavor." sentences where the truth value depends on the referents: "I am awake right now." (indexical) "The team went on to win the cup." (context) sentences with metaphor / poetry / nonsense:...


33

These are simple conclusions from inductive reasoning. I don't like it when I hit my thumb with a hammer. I don't like it when I hit my head on something. Even though I haven't been hit on the head with a hammer, I can assume it would hurt just as much if not more than the other things I've hit my head on. From personal experience and pop culture I know ...


26

The answer is a point of contention between realism and anti-realism. Truths that "do not have evidence" are termed verification-transcendent truths (coined by Dummett), and realists are committed to their existence. Anti-realists, on the other hand, hold that unverifiable in principle statements have no truth values. So if no trace of dinosaurs remains, ...


22

This is a very huge question spanning multiple fields in philosophy. I do not have the expertise to cover all of these, so I'll focus on my personal favourite, the Philosophy of Mind aspect. As it stands there are no universally agreed upon answers to whether humans are different from computers in how they think. There are people on both sides of the ...


21

I think it is a mistake to assume that there exists something like a context-independent notion of truth. Let me explain what I mean with the context dependence of truth. Consider the following simple question: Did Han shoot first? Now you can observe that in the real world, as far as we can tell, Han didn't exist at all. Obviously a person that doesn't ...


20

The quote about facts gets it pretty right. A fact is, for many philosophers, a part of reality (Russel, for example). So as there are people and tables and chairs in our world, there is also the fact that I am sitting on the chair. It is as real as the chair itself. You often see some kind of brackets when someone speaks about fact, so for example: < I ...


17

I agree with the comment of @Philip Klöcking concerning the success story of empiricism in science. Apparently philosophy is not based on experience, in particular it is not based on observation. But the great benefit of the scientific method is the possibility to check its results. It is possible to derive consequences from scientific theories and to test ...


17

It is not just that empiricism works, and in 300 years has brought us from semaphore lines to global high speed interconnects, or that non-empiricism is a fervent breeding ground for falsehoods and mysticism; those are true and more than justify aversion to the magical, but they don't explain why that should be the case. Rather, it is that in the modern day ...


16

In the classical logic something is neither true nor false if it is grammatically malformed to have a truth value, so 2+5 or "x is blue" are not "true", but not "false" either, they are not truth-apt. The classical assumption was that all truth-apt expressions can be distinguished by syntax alone, i.e. there is a clear way to tell from how they are formed ...


16

The OP asks the following: Can I write or utter any sentence which is neither false nor true? Yes. An example would be Tomorrow I will rise at precisely 6 am. That sentence today is neither true nor false. However, I will know tomorrow, but by then I will have a different sentence, perhaps: Today I rose at 6:30. That sentence could be viewed as either true ...


15

Despite some claims, the Cartesian myth that math is independent of physical reality is arguably false. Mathematics is NOT independent of the physical systems which embody it. Physical systems are structured in such a way that mathematical statements supervene on them. An excellent introduction into how mathematical truths are functions of conceptual mapping ...


14

tl;dr: Yes to pragmatists; no to everybody else: For them, mathematics is about correctness, not about truth. While it is true that mathematics obviously was — and, perhaps less obviously, still is — inspired by our (perceived) reality, it is one of the essential traits of mathematics that it quickly and rigorously abstracts from that reality.3 ...


13

Some informal definitions first: Soundness is the property of only being able to prove "true" things. Completeness is the property of being able to prove all true things. So a given logical system is sound if and only if the inference rules of the system admit only valid formulas. Or another way, if we start with valid premises, the inference rules do not ...


13

This is why people invented words like "probably": if a man habitually has yoghurt every morning then tomorrow morning I expect him to have yoghurt at breakfast though of course there is a small chance that he might not. That small chance is where the attention of scepticism directs itself; scepticism by itself - pure sceptism otherwise known classically ...


12

Your (1) and (2) are not enough. Here is an example: suppose I have excellent reasons to believe that the earth is round (I've seen photos, listened to lectures, etc.), and that it is in fact true that the earth is round, but nevertheless I do not believe it (because I'm irrational). Clearly this is not a case of knowledge. There is a recent view, however, ...


12

Is every sentence we write or utter either true or false? NO. A sentence is "a textual unit consisting of one or more words that are grammatically linked. [... The] words [are] grouped meaningfully to express a statement, question, exclamation, request, command or suggestion. A question is neither true nor false.


12

Maybe not so much a philosophical / logic-based argument, but in science there is a very helpful principle that most reasonable people (not only scientists) seem to have internalized: Extraordinary claims require extraordinary evidence. (or, to flip it around, not much evidence is needed to support a very mundane claim) This snappy quote is attributed ...


11

It is a natural idea, but unfortunately the answer is no, it is not feasible. The root of incompleteness is not numbers, but the possibility of (implicit) self-reference, arithmetic is just the simplest structure that already realizes that possibility. In fact, one does not even need the Peano arithmetic, but a much weaker Robinson arithmetic without even ...


11

Well, in English you would use the subjunctive tense and say, "possibly I could have had a cat in my room, but in fact I do not." That's a reasonable statement to make. "I could have been a doctor" is another statement of the same kind that is considered normal to utter. The meaning of such statements is tied to an implicit idea of ...


10

The answer you get will depend on who you ask. There is no consensus within philosophy, so depending on which philosopher you ask the answer may be either yes or no or maybe or it's-impossible-to-tell. However, within the natural sciences there is pretty good consensus that we are just (analog, noisy, non-deterministic (due to quantum mechanics)) computers....


10

Here is another motivation for dialethism - inconsistent set theory: It allows for a formalisation of naive set theory with the naive expectation that any predicate determines a set. That is, it's another solution to Russell's paradox apart from the theory of types or ZFC. So it has a universal set, and Cantor's paradox is now a theorem. This theory proves ...


10

There are a few things to unpick, here. First, there's a difference between provability in a formal system, and "truth", which is a question of the relationship between language acts and facts. The statement "Juh mapple Neele" is neither true nor false, but nonsense, unless it is recognised as a poorly pronounced version of the French phrase Je m'appele ...


10

Timm Lampert, cited by the OP, quotes Wittgenstein (§8 of Remarks on the Foundations of Mathematics, Appendix 3): ‘True in Russell’s system’ means, as was said: proved in Russell’s system; and ‘false in Russell’s system’ means: the opposite has been proved in Russell’s system. Lampert claims Wittgenstein is assuming what needs to be proven: Whether P =...


10

“You can’t have i apples” As @Conifold points out you cannot even have √2 apples. I'd go further. Can you have -2 apples ⅓ apples? I'd say (from a certain pov) no. All physics is based on measurements All measurements come from instruments Which can only ever deliver integral non-negative bounded multiples of least count Note: I added the “bounded” aka ...


9

Tarski's Convention T is not strictly speaking a definition principle for truth - it is an evaluation condition on whether a given axiomatically theorised predicate is a "Materially Adequate" definition to count as a Truth predicate. The work that Tarski did in showing how a truth predicate could be defined was not in presenting the T-Schema. That "snow ...


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