Can we know any truths without evidence?
This is such an interesting question, and one I have spent a lot of time on over the last 40 years.
The answer I will give may seem nonsensical, and it isn’t.
The short answer is NO !
The slightly longer answer goes beyond much that has been accepted throughout history.
It seems that the idea of truth, as any sort of absolute and unchangeable thing, is an illusion.
It seems that it is the sort of illusion that occurs naturally to all entities that evolve from a very simple start.
When we start out trying to make sense of the world, we need to assign some sort of reliability or usefulness value to assertions. The simplest such assignment is a binary – giving us values like true and false, right and wrong.
Uncertainty comes later. We move next to a trinary – “yes”,”no”, “maybe”, and eventually some of us get to mathematical probability (via the route of truth).
Then some of us start to seriously investigate what we are.
How did this collection of 100 trillion cells that is me get to be this way?
What are the major systems within each cell that allow the cells to cooperate together to organise into the body that allows me to experience being me?
What is it that is experiencing being?
What is that being experiencing?
What might the ideas of knowledge and truth mean to such a being?
The evidence is now clear beyond any shadow of reasonable doubt, that human beings require experience (evidence of reality) in order to train their neural networks to have an experience of being. If they are to know language, then they need a culture of language.
Children who do not experience language do not spontaneously learn it.
In order to learn even the relatively simple ideas of truth and falsity (as illusory as they are), we must have vast amounts of experience (evidence).
It seems that what does the experiencing is a software entity within the brain of a human being.
It seems that what that software entity experiences is a software model of reality created within the neural networks of that brain – resulting in part from the past experience of those neural networks and the expectation functions that they have developed from that experience, in part from the current data being delivered by the sensory systems, in part by the distinctions that brain has made as to the objects, abstractions and contexts present, and in part the preferences of the software entity.
We seem to be the result of a very complex set of processes, and those processes seem to be firmly based in evidence, at levels that most of us rarely if ever consider.
Even the most abstract of conceptual realms has to start from a set of abstractions made from observations of reality. So even our most abstract mathematical or logical systems of thought have their genesis in the evidence presented to our brains by experience.
The term “by definition” hides a multitude of evidence in its assumptions.
The term “self evident” is a logical nonsense. It is a shorthand for saying, these things appear clearly to be so to the human mind, but we do not understand the human mind sufficiently at this point to have any real idea about how or why that is so, but it is clearly so, as evidenced by the fact that we all think this way.
So the sort of truth we all look for as children, the sort of truth Plato and many others have sought, seems, beyond any shadow of reasonable doubt, to be an illusion based upon inadequate knowledge and understanding.
It seems that Heisenberg uncertainty, and quantum uncertainty, and Goedel incompleteness are fundamental aspects of this reality within which we seem to find ourselves.
It seems necessary to accept uncertainty at all levels, in all things; then to work with the resulting probability functions.
It seems that truth really is an illusion based upon evidence.
Hi OM @ Bill
The difference, is that the term “seems necessary” is a probability function derived from a set of experiences (aka evidence). It is a beast of a different sort from that which most begin with.
It is most certainly “some sort of reliability or usefulness value” – and it is not a binary one – but rather a context specific probability function – different for every individual in every context (where context is specific to space and time).