What does "extend the analogy " mean? Could you explain it to me?
We are so attached to the use of analogy that it frequently happens that we adopt an analogy and continue to use it in ways that make no sense at all ─ in fact, in ways that are simply absurd. Take the statement, “The razor edge of his intellect will be blunted by constant use.” The comparison of a person’s mental ability to a sharp razor is certainly striking and illuminating ─ illustrating how the minds of very intelligent people work. But it is absurd to extend the analogy by implying that, just as a razor will be blunted by constant use, so will our minds if they’re used often. Far from becoming worse from too much use, the mind is improved by it, and people may become tired from overwork, but that is a different matter. Once they have rested, they will find that their minds have become sharper, not duller, as a result of the endeavor.

What does "extend the analogy " mean? Could you explain it to me?

Question

What does "extend the analogy " mean? Could you explain it to me?
We are so attached to the use of analogy that it frequently happens that we adopt an analogy and continue to use it in ways that make no sense at all ─ in fact, in ways that are simply absurd. Take the statement, “The razor edge of his intellect will be blunted by constant use.” The comparison of a person’s mental ability to a sharp razor is certainly striking and illuminating ─ illustrating how the minds of very intelligent people work. But it is absurd to extend the analogy by implying that, just as a razor will be blunted by constant use, so will our minds if they’re used often. Far from becoming worse from too much use, the mind is improved by it, and people may become tired from overwork, but that is a different matter. Once they have rested, they will find that their minds have become sharper, not duller, as a result of the endeavor.

What does "extend the analogy " mean? Could you explain it to me?

Answer

An analogy is a comparison between one thing and another, typically for the purpose of explanation or clarification.

In this case they compare the human intellect (mental abilities) and a razor edge.

You extend the analogy when you "continue to use" the analogy and apply it to some of the attributes of the two things you are comparing.

Sometimes extending the analogy is not appropriate because although the analogy works, extending the analogy to specific attributes doesn't work.

In this example comparing the human intellect to a razor edge works because both are "sharp". But while the razor becomes blunt/dull the more you use it, the human intellect becomes sharper the more you use it.

Answer

I believe that when someone attempts to extend an analogy, it really provides an opportunity for the analogy to be explained or validated. In the case of the example given, the analogy suffers from a failed extension.