Why did John Searle argue that understanding cannot consist only of computational processes?

In the philosophy of mind, John Searle argued that understanding cannot consist solely of computational processes because such processes are limited to the manipulation of symbols based on their formal or syntactic properties, rather than their semantic properties (their meanings).123

To demonstrate this, Searle introduced the Chinese room argument, a thought experiment in which a person who does not know Chinese sits in a room and follows a manual to match input Chinese characters with appropriate output responses. Although the person can produce responses that appear perfectly intelligent to a native speaker, they possess no actual understanding of the language.143

Searle concluded that because the person—functioning like a computer program—can simulate intelligence through rule-governed symbol manipulation without grasping the meaning of those symbols, computation alone is insufficient for genuine understanding or thought. Furthermore, Searle maintained that because consciousness is an intrinsically biological phenomenon, it cannot be realized by nonbiological machines that merely mimic these computational processes.1235