One form of definition is the statement, A is B. However, all statements of the form, A is B, are not definitions since the verb, is, has many meanings. Where 'is' means equivalence A is B may be may be a definition.

"Green is the colour on the visual spectrum with a wave length of 530 millimicrons." is a definition of green. It is a definition since B is A makes equal sense. It is also a truth. That type of truth is a tautology. A tautology states an equivalence relationship. This is the way truth is used in mathematics. A mathematical proof proceeds from equivalence relationships.

The Bible uses the word, truth, as neither a definition nor a provable statement.

Luke 9:27 But I tell you of a truth, there be some standing here, which shall not taste of death, till they see the kingdom of God.

The above is a prediction. The prediction was false since the kingdom of God has not arrived, and we can assume that all standing there are now dead. The speaker was not lying because he could have believed in what he predicted. Nevertheless the prediction was false.

That kind of truth is also found in Marxism which makes the prediction that there will eventually be a classless society. I cannot prove that prediction is false, but I have no reason to believe it is true.

In John 8:32 we find “And ye shall know the truth, and the truth shall make you free.” Here truth is neither a tautology, a provable statement nor a demonstrable fact. It is belief. One of the meanings of truth is belief.

Belief is neither a tautology, a provable statement nor a demonstrable fact, but it is confused with them. I think it is best for me to get along without that kind of truth.

Except for mathematics, demonstrable facts and tautologies I will operate on the basis of the most plausible explanations and not engage in a search for truths that purport to explain everything as found in religions and prescriptive ideologies.

I believe, as usual, that david f is correct.

Turning to the earlier topic and to rephrase Herbert Morrison (who by the way is 107)... "Oh, the philosophy!"

Regardless of whether it 'is' a 'not pipe', it is a pipe that can be used by a non-smoker in a no smoking area.

Are you being sarcastic?
Mr Opinion,
No I'm not sarcastic at all. Those engineers I am forced to co-operate with (if I don't I don't have a job) are literally inexperienced, devoid of practical sense, egoistical gits. Not just one or two but literally the majority have no practical sense whatsoever. Those who actually are capable of producing good work are very few indeed. The majority are mere hangers-on who get employed simply because idiotic Govt policy stipulates that consulting engineers are to sign everything off. No question about their competence is ever asked. All they require is a few Uni degrees & they've got all over any other competent builder or mechanic etc. Those degrees have cost all of you many millions of wasted Dollars over the years simply because our even more incompetent bureaucrats do net question the competence of someone with a Uni degree. For some idiotic reason a Uni degree instantly places an engineer above all practical & common sense. That is exactly the reason for having so many infrastructure problems & associated expenses. I recently had a case where about an hour of manual work could have solved a long standing problem yet the consulting engineers insisted on spending 100 Grand & we still have the same problem. Even tough I physically proved that the one hour job works they still wouldn't give in. Now we'll have to spend more of your tax dollars to fix the problem plus give these morons another handsome payout for their own stuff-ups. That is a fact!

It's a good question.

The very variability of answers in this thread shows how difficult it is to get mankind to agree on anything.

But on the other hand, they can't all be right because they contradict each other. They could all be wrong. But I think truth is possible, and not just in mathematics, for the following reasons.

There's two ways of looking at it. The truths of mathematics seem to be binding on us. We can't think how they could be any other way. (That doesn't mean they're "absolutely" true of course. They could only be true relative to themselves.)

Mathematics is perhaps the model of discourse in which statements can be known and demonstrated to be true or false. Any other statement seems obviously false. But why? What is it about mathematical truths that seems to command such universal acceptance? By acceding so, are we admitting that there is a direct connection between mathematical truths, and objective reality? Or is it just self-defining?

But my point is, don't the truths of mathematics and logic underlie other truths about social life?

For example, if we put fertiliser on a field, its productivity will increase - up to a point. After that, it doesn't matter how much you put on, it's not going to increase productivity.

Therefore nature imposes limits on human action. And these limits are, in theory, logically knowable as truths, because we can apply logic to known axioms.

We accept that axioms, logical deductions, and valid conclusions are possible in geometry and mathematics.

The same must be true in respect of human action because nature imposes knowable limits on human action, e.g. action takes place in time. Therefore we are capable of truthful statements in respect of human action.

C'est certainement un tuyau mon cher Poirot !

It is certainly a pictorial representation of a pipe, Ludwig.

But it's not "a pipe".

If it was a pipe you would be able to stuff it with tobacco, light it, and sit back and have a good long puff.