Error
To define error, we must first define falsity as error is a species of falsity. Falsity in general is the opposite of truth in general. Truth is conformity between thought and thing, and falsity non-conformity between thought and thing.
Like truth, falsity is threefold, ontological, logical, and moral. Ontological truth, is defined as conformity of thing with thought, logical truth, as conformity of thought with thing, and moral truth, as conformity of speech with the speaker s internal judgment. Accordingly, ontological falsity will be disagreement of thing with thought, logical falsity, disagreement of thought with thing, and moral falsity (or a lie) disagreement of speech with the speaker`s internal judgment. Here, logical falsity is ordinarily called error.[1]
The disagreement of thought with thing may be taken in two ways, negatively and positively. Regarded negatively it consists in the intellect not representing an object exhaustively or fully. Thus viewed it is merely a partial negation or absence of truth, or, partial ignorance. In positive disagreement, the mind expresses an object other than it is, or, in other words, in which the mind ascribes to an object what does not belong to it, or denies of an object what does belong to it.
[1] Rother Aloysius, Truth and Error-A Study in Critical Logic (1914), B Herder 17 South Broadway, London, pg 9.