Michael Egnor argues that, compared to the Strong Anthropic Principle — the universe is objectively fine-tuned for life — the Weak Anthropic Principle aims to avoid evidence and subvert discussion:
The Weak Anthropic Principle, which is widely held by atheists, is meaningless: Only in a universe that permits the existence of intelligent beings can intelligent beings exist — i.e., only a universe with intelligent beings can be a universe with intelligent beings. The Weak Anthropic Principle is a tautology. And a tautology is not an explanation. It’s merely a sentence in which the predicate is the same as the subject. It’s meaningless.
The Weak Anthropic Principle isn’t a scientific explanation for the fine-tuning in the universe. It isn’t science and it isn’t an explanation of anything — no tautology is.
To get a better sense of the tautological nature of the Weak Anthropic Principle, consider two anthropologists discussing the remarkable emergence of language in man. One anthropologist says, “There is nothing at all remarkable about the emergence of language in man, because if language had not emerged in man, we wouldn’t be able to ask the question.” The other anthropologist, if he were a sensible man and a good scientist, would dismiss his colleague’s nonsensical theory because it’s tautological. It explains nothing. The remarkable emergence of language in man still requires explanation.
To sum up, tautologies like the Weak Anthropic Principle or the “Weak Language Emergence Principle” are literally meaningless. They are certainly not scientific explanations or explanations of any sort.
By contrast, the Strong Anthropic Principle — the theory that the universe is designed for life — is a scientific explanation. Its implications are revolutionary and are consistent with an enormous range of data in cosmology, physics, and biology that point unmistakably to the existence of an Intelligent Designer.
Michael Egnor, “Weak Anthropic Principle? Not an explanation but a tautology!” at Mind Matters News
Takehome: “If the universe were not fine-tuned, we wouldn’t be here to know it” is a tautology because the subject and the predicate mean the same thing.
You may also wish to read:
Our universe survived a firing squad and it’s just an accident? According to the Weak Anthropic Principle, if things weren’t the way they are, we wouldn’t be here and that’s all there is to it. Given the odds, a philosopher likens the Weak Anthropic Principle to surviving a firing squad and concluding, incuriously, well… that’s just the way things are.