One problem is equivocation.

Two things can be (a) not the same and (b) linked. So being the same and being linked are not equivalent concepts.

Another problem is sense:

"Thing-in-itself is appearance" does not sound like an English sentence. It may be garbled Kantian technical language. If so, then it needs to be expressed clearly. The same applies to the second statement.

I suggest you tackle the second problem as a priority. If a sentence does not make sense then it cannot be used in any argument.

Thanks for your comments.
You mean the fallacy of equivocation?
I am desperately trying to track down the precise words...
It was a book by Henry Allison... I am sure he said "the thing-in-itself is appearance", or "the thing-in-itself is basically appearance" ...but he made the claim that they were the one and the same thing.

You mean the fallacy of equivocation? — KantDane21

It could be that, if the claim is that (1) and (2) mean the same. Or it could be a non-sequitur, if the claim is that (2) entails (1) or the other way round.

Making sense of either statement is the first problem.

The meaning of the symbol "/" in (2) may be important. It is sometimes used to mean: "I am unable to find the right word and so I am writing two words which are both inadequate but which together may cause enough vague confusion for my lack of coherence not to be immediately obvious." That is an awful lot for "/" to mean and it may not mean that in this context. It's a very hard-working symbol.

If they mean the same (and I considered that), I think he is being pretty sloppy with terminology.

I would say it is a non-sequitur (if (2) entails (1)).

I am still trying to track the exact quote, but he stated elsewhere:

one's will is is an object for a subject, but the “in-itself” of will—the thing-in-itself—differs from one’s “experience of it as an object".

So the thing-in-itself is an object. we experience it as such.
And the thing-in-itself has an inner essence that we do not experience.

Doesn't really make a great deal of sense to me, although I think he is referencing a Platonic view, e.g.,...all beautiful things participate in the Form of beauty. But even then, Plato distinguishes the objects and the Forms.

I think he is being pretty sloppy with terminology — KantDane21

Firstly I would double-check the third-person pronoun there before holding forth on that complaint.

Good question!

The Oddball's Oddball is Paul Erdős (Hungarian mathematician).

Noam Chomsky (linguist with Erdős number 4) is connected/linked to Richard Dedekind (mathematician with Erdős number 7) through Paul Erdős.