First, let me say that I am not a Secular Humanist (I don't like ISMs in general, I prefer to actually consider my thoughts individually). I personally don't like the connotation of "Human" in that equation. I think humans are petty, evil, nasty, little shitstains on the planet and I think the planet would be better off, on the whole, without us around. I love my family and friends but come on, be honest for about 30 seconds and think about it. However, I don't advocate wiping us all out either because that's exactly the kind of petty, evil, nasty shit I was talking about in the first place. So we're kind of stuck with trying to make the world a better place.
[the above is pretty laden with sarcasm - please do try to read between the lines]
Anyway, I don't hate Secular Humanism and I think it has some good ideas. What I do dislike very much are absurdly irrational diatribes so let's get back to the content of the article that I wanted to comment on.
The article primarily attacks secular humanism on the basis of this bit in the manifesto: In this way there is no impenetrable wall between fact and value, is and ought. Using reason and cognition will better enable us to appraise our values in the light of evidence and by their consequences.
His primary argument is to invoke Hume's Law: you cannot derive a moral "ought" from a factual "is.".
This is an appeal to authority which undermines the entire argument. It MIGHT be true, but all evidence is to the contrary. He doesn't at all address John Searle's 1964 "How to Derive 'Ought' from 'Is'" or other attacks on Hume's assumption, although that isn't necessary to punt Hume out of the drivers seat.
What Hume was unaware of was Quantum Mechanics, Attractors in non-linear nonlinear dynamical systems, and the computational nature of the universe (not that it can be modeled with mathematics but that it fundamentally forms computation).
The absolutely unquestionable fact (and you can do this with sand, tinkertoys, water, just about anything) is that certain arrangements of physical materials allow CHOICES to be made. Choices take input data (either stored or gathered from the environment) and make decisions about it. This is how computers work, this is how brains work. At the lowest level the data and the choices made are so incredibly deeply abstracted from 'reality' it seems difficult to understand how they relate to our experience but by building up millions of bits of data and making trillions of choices we build up ever more complex abstractions. We KNOW this with computers. The exact same 'bits' in the computer make up numbers, letters, words, documents, pictures, sound, movies, AND THE PROGRAMS WHICH OPERATE ON THEM.
It's that last bit I stress because the data IS the program and it's that knowledge that blows Hume's presumption out of the water.
We have 'oughts' built into our individual cells by billions of years of evolution. Oughts that we have absolutely no conscious control over (only at the molecular level are such decisions being made, should I produce more ATP? etc). Oughts that are absolutely fundamental to life existing.
We have 'oughts' that are built into our brains by 10's of millions of years of evolution. These Oughts we have no little or conscious control over either. "Should I contract this muscle? Yes, because CO2 levels are rising"
We have 'oughts' that we do have 'conscious' control over - I say 'conscious' because I don't assume that we have Free Will and indeed, the research is rather strong suggesting that our apparently conscious decisions are made subconsciously.
It is at this level that we begin to consider the consequences of our actions - "should I eat another slice of Pie?" is of absolutely no qualitative difference from "should I attack that person violently?" In BOTH cases our subconscious knowledge and biological factors we are utterly unaware of will drive trillions of choices to be made which will ultimately bubble up into our conscious and result in action or inaction. "Moral" choices aren't somehow magically different from choices that evolved as necessary for survival.
The presumption should be that human beings are (extremely complex) machines, following the laws of nature, performing computation until you can prove otherwise because those are the facts that we KNOW and other than specific details no fact of our existence is unexplained by those assumptions. And in that model there is no place for the magical formation of 'oughts', they form naturally.
And here is the bottom-line, I can write a fairly simple program that learns from its inputs and forms 'oughts' as a result. Not a priori oughts, but oughts that evolve naturally out the consequences of the execution of the program. They will not be 'absolute' oughts except in the sense that are likely to be some cases where there are no viable alternatives (when there is only one possible answer).
I'm sure it will take years to fully develop this such that the majority of people can 'get it' but it's rather obvious to me and I think this is at least a good informal start on communicating (in the ~30 minutes I had to write this) why I find this objection absurd.