Is the statement "Claims demand evidence" always true?

[Mudhammam]

Yeah me too... almost tears but not quite... just very moving and involving... like being a direct witness at a pivotal moment in history. I have the feeling I'm going to be reading it many times in the future; I want to really understand the arguments in depth, and see what arguments I'd put against it in a thorough refutation. My main objection is that it seems to take too much for granted... essences for instance are things I've only ever really thought about in neuroscientific terms (because it is neurons that 'extract' the essences of things they represent... that's what they do... so all this talk of categorisation, classes etc seems to me to be only describing how the brain works rather than talking about anything objective), and absolutes of beauty, truth, goodness etc again are things that I see as essentially arbitrary perceptions in the mind... that might be different, or non existent, or replaced with something else in different animals. So I don't take any aspect of perception for granted even if it appears to be something that is objectively 'out there'. But by reading this stuff more thoroughly I'm hoping I'll get a better and more foundational understanding of all this causes, essences, absolutes stuff and see if it really is at odds with my understanding of the mind, or whether I'm just conflating the two and there's room for both interpretations to co-exist.

Anyway, thanks for your further reading list I'll try and read them in roughly the order you suggest. At the moment I've got a 'complete works' compendium of Plato's to go through... you can't really argue with 49p for all of that on Kindle... so that should keep me busy and what's cool is the one I've got has got a lot of analysis and commentary as well, so that'll be very helpful in getting the very most out of each one

That sounds like a wonderful plan.  I'm currently in the latter stages of a project that began about two years ago, which was an undertaking to read all of the major philosophers and their primary works beginning with Plato (well, actually, I began with all of the important Ancient Near-Eastern texts, at least those that were known by the 1970s or whenever the compilation was published; I know many more have since been discovered; and Homer -- my goodness, if you haven't read Homer!) and working my up towards the present-day.  Currently, I am about to start Kant once I finish this more recent philosophy book by Derek Parfit called Reasons and Persons (I've taken a number of detours along the way), and honestly, though I now understand many of the issues much better, talk of abstract objects like numbers or essences or substances or beings is just really intuitively difficult, I think, because we are such sensual creatures.  You'll find this not only to be a common theme in Plato's works, but in most of Western philosophy -- the tension between mind and body and the attempt to make sense of how it is that subjects perceive objects, and what these tell us about both, one or the other, or neither; in a word, what is "truth" and how can one understand it?  The 19th century mathematician/philosopher Alfred North Whitehead once famously said that, "The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato."  I'm not entirely sure I'd disagree.

Now, when you write that 

My main objection is that it seems to take too much for granted... essences for instance are things I've only ever really thought about in neuroscientific terms (because it is neurons that 'extract' the essences of things they represent... that's what they do... so all this talk of categorisation, classes etc seems to me to be only describing how the brain works rather than talking about anything objective), and absolutes of beauty, truth, goodness etc again are things that I see as essentially arbitrary perceptions in the mind... that might be different, or non existent, or replaced with something else in different animals

I have to inquire, if neurons weren't, in evolutionary terms, designed to track truth -- not for the sake of truth but simply because the more accurate the representation of the world, the easier can harms be avoided and the more can energy-saving advantages be procured -- then what explains our success as a species at overcoming nature and the ignorance she fosters upon us all, especially when this ignorance can be so dangerous?  Did humans invent the concepts or merely the terms by which to communicate them?  Did they invent the "categories" -- of space and time and relation and action -- and the internal consistency that allows us to map our signs/symbols and their theoretical relations onto a world? And through it we have discovered ourselves to be this privileged species, living on a giant ball that orbits around a much larger ball of gas, all of which is in fact less than a spec of dust in the grand scheme of things!  It's all too odd to rule anything out, but it seems less odd to me that the world is as fundamentally abstract as it is physical, perhaps counterparts to the ancient notions of "form and "matter," rather than that the world is only a figment of my mind.  Can one really believe that the only difference in beauty between the Sistine Chapel and some ordinary six year old's finger painting is an arbitrary or irrational judgment formed by one's brain that the former is far more beautiful?