[HangnJudge]

You cannot, however, use the notion hammer as an explanation of what a hammer is. Instead, you'd have to introspect, peruse your memories, and find out what observations or non-hammer concepts you used to form the concept of hammer.

Ah, but now you are using reason to study the hammer, not the hammer itself
We still have the problem of using Reason to explain Reason,
Logic to understand Logic

[beavus]

Ah, but now you are using reason to study the hammer, not the hammer itself

Of course. Understanding is the function of reason, not of hammers.

We still have the problem of using Reason to explain Reason, Logic to understand Logic

But we never had that problem. Reason is the tool for understanding everying, including reason.

TOOL.........FUNCTION........EXAMPLE OBJECTS OF FUNCTION
hammer......pounding.............nails, rocks, hammers
reason........understanding......nails, hammers, reason