I get stuck by the following sentence from this article: Noam Chomsky: The False Promise of ChatGPT.
The crux of machine learning is description and prediction; it does not posit any causal mechanisms or physical laws.
I thought crux is an uncountable noun, but it turns out that its plural is cruces. Therefore, I am wondering why not the form of 'cruces' + 'are': The cruces of machine learning are description and prediction;
If the New York Times article is right, then I thought this umbrella form should also be right: singular noun + is + something + and + something
For instance, these sentences:
- My key to happiness is mindfulness and forgiving.
- The crime enabler is Tom and John.
I don't think they are right at all.
One of my attempts to solve this myself:
The aforementioned 'crux' sentence should be comprehended as 'The crux of machine learning is (the combination/integration of) description and prediction'
What am I missing? Thanks in advance.