Neil Degrasse Tyson

[Napoléon]

If that were true there wouldn't be the term Agnosticism.  Just to make things REALLY complicated, scroll down to Note No.2 from the following Wikepedia article where a still living philosopher would disagree with your definition.

Agnosticism

Rowe, William L. (1998). "Agnosticism". In Edward Craig. Routledge Encyclopedia of Philosophy. Taylor & Francis. ISBN 978-0-415-07310-3. In the popular sense, an agnostic is someone who neither believes nor disbelieves in God, whereas an atheist disbelieves in God. In the strict sense, however, agnosticism is the view that human reason is incapable of providing sufficient rational grounds to justify either the belief that God exists or the belief that God does not exist. In so far as one holds that our beliefs are rational only if they are sufficiently supported by human reason, the person who accepts the philosophical position of agnosticism will hold that neither the belief that God exists nor the belief that God does not exist is rational."

You do realise that even by using the definition you are using (which I wouldn't recommend, I'd suggest Oxford English dictionary, it's far more universally accepted and less wishy washy), it doesn't even make it incompatible with atheism nor does it justify in any way your assertion that NDT is not an atheist.

Let's look at what your definition actually says though, seen as you brought it up:

"agnosticism is the view that human reason is incapable of providing sufficient rational grounds to justify either the belief that God exists or the belief that God does not exist"

So what your definition describes, despite it seemingly contradicting itself by first talking about disbelief* in 'the popular sense' and then clarifying with only talking about belief in 'the strict sense', is someone's view on what is knowable, or rather, what is rational to accept. And in both your definition, and the definition that Oxford uses, agnosticism refers directly to a view about knowledge, or what a person deems to be a rational position.

This really isn't even a difficult concept. 

Gnosticism = about knowledge

Theism = about belief

So your definition, my definition, any definition, does absolutely nothing to suggest that NDT cannot hold these views and also lack belief. And anyone with a grain of intellectual honesty knows NDT lacks belief in gods, that's evident in everything he's ever written and said. He's quite famous for saying that science and belief are incompatible, for example. If this doesn't strongly suggest that he disbelieves in gods (which by definition, is atheism), then I don't know what does. 

Now for step 2. 

Look up the definition of atheism in the Oxford dictionary. If you argue after that then you really are a plank. 

NDT is a scientist, not a philosopher so I'm guessing that he's going by the popular definition of the word.

The neuroscientist, Ramachandran, doesn't class himself as an atheist even though he doesn't believe in a personal God.

That's all nice and rosy but it doesn't make a blind bit of difference to anything here and it's actually, completely irrelevant. You need to really understand the word 'atheist'. If you do that, then to argue that NDT is not one, you have to demonstrate that he actively believes in a god. Good luck with that. 



To simplify my points: neither believing nor disbelieving isn't really possible. Your own definition admits as much, despite opening with it. Likewise it's not possible to both believe and disbelieve at the same time. So you either do one or the other, and if you're 'agnostic' about something, especially a claim, and say 'you don't know', by default, by definition, you lack belief that it is either true, or false. Because how can you actively believe in something while maintaining (that by your own definition) it's irrational to hold the belief that said thing is true? Now NDT could well be an agnostic theist, but that would make him irrational. If there's one thing about NDT we can all work out, it's that he's not a very irrational man.


*a very important point to note is that disbelieving is not the same as believing something is not true. I think this does a better job of explaining than I could: http://atheism.about.com/od/atheismquest...belief.htm