If you are wondering if there is baking soda in a container, you could pour some vinegar in there. If there is no bubbling of carbon dioxide, then there was no

If you are wondering if there is baking soda in a container, you could pour some vinegar in there. If there is no bubbling of carbon dioxide, then there was no baking soda. This is not circular logic, this is an observation that necessary evidence that would have accompanied the existence of something isn’t there, so the thing itself isn’t there.