I don't think "very" is the best definition for that idiom.
Collins , American Heritage and Cambridge dictionaries of idioms all define it more like more like "clearly" or "above all else."
This meaning is more easy to distill from the component parts.
"
[X] is nothing if not [y]"
means that if [y] is not a good description of [X] , then nothing could be.
[Y] is the best possible description.
ell.stackexchange.com/users/11733/Adam
Phrases like "either… or", "neither… nor", "if… then… else…", "between… and… (inclusive)", and "nothing if not" explicitly use multiple different logic operators.
Some of these logic operators (such as "neither", "nor", and "inclusive") are rarely used in informal speech.
Similarly, informal speech rarely uses so many different logic operators in a single expression.
These are hints that these logic operators are being used to express formal logic, and the meaning can be derived logically.
Here are the assumptions: 1) <
X> exists. 2)
<X> is nothing if not <
Y>.
We seek to prove that: 3) <X> is at the very least <Y>, and 4)
<X> is certainly <Y>.
The argument is fairly straight-forward: 5)
Either <X> has the feature <Y>, or 6)
<X> does not have the feature <Y> 7)
If (6) is true, then <X> "is nothing", per (2).
8)
If <X> "is nothing", then it does not exist. 9)
But we have assumed that <X> exists, per (1),
so neither (8), nor (7), nor (6) can be true.
10)
Therefore (5) is true.
We know that <X> has feature <Y>. 11)
We have proved that <X> is certainly <Y>. 12)
Since the assumptions state nothing else about what <X> is, or is not, we have not proved that <X> is more than <Y>, nor have we proved that <X> is <Z>
.
13) We can only state with certainty
that <X> is at the very least <Y>. 14)
Q.E.D.
ell.stackexchange.com/users/9100/Jasper
It's an abbreviation of a rhetorical device.
If we say "Canada is nothing if not beautiful" then we are saying "if Canada isn't beautiful, then it isn't anything at all."
But it's understood that Canada does have other properties; for example, it's large and full of maple trees.
So the purpose of setting up the comparison is to say that Canada is beautiful, and its beauty is as notable as, or more notable than, anything else about it.
ell.stackexchange.com/users/5937/hobbs
( source )
Shakespeare used this idiom in Othello (2:1):
"I am nothing if not critical."
[c. 1600]
If I am not critical (which, I am very much), then I am nothing.
ell.stackexchange.com/users/None/
In my experience, this idiom is often used to disparage.
There is often an implied criticism.
To say that someone is "nothing if not {X}" can mean that the person is rather too {X}, or {X} at the expense of {Y}, i.e. that the person is lacking in other qualities.
She is nothing if not thorough.
(translation:
She gets lost in the details ).
He is nothing if not persistent.
(translation:
He can be a nuisance ).
He is nothing if not logical.
(translation:
He can be wooden in his approach to things .)
He is nothing if not practical.
(translation:
He is relentlessly pragmatic )
He is nothing if not predictable.
(translation:
He is a creature of habit. )
ell.stackexchange.com/users/10264/Tᴚoɯɐuo
nothing if not  =  at the very least; certainly   How does  the juxtaposition of  nothing + if + not  produces the above definition on the right? What semantic notions underlie and connect the left-hand and right-hand sides? I ask not about this phrase's definition which I already understand;
How does 'nothing if not' mean 'at the very least; certainly'?
ell.stackexchange.com
<phrase-meaning>
ell.stackexchange.com/questions/48359
ell.stackexchange.com/users/8712/AYX.CLDR
This is a rhetorical device. If we say "Canada is nothing if not beautiful", then we are saying "if Canada isn't beautiful, then it isn't anything at all." However, some claim that there is an implied criticism in this idiom, which can be used to disparage. This is a rhetorical device explicitly using multiple logic operators. It often contains implied criticism.
This is a rhetorical device explicitly using multiple logic operators. This idiom often contains implied criticism.