Make the validate functions public so they can be used for custom rules.

[ghost]

This can be useful if a developer wants to change a value before validating it.
For example a user might post a url without a protocol. Rather than returning a validation error it might be preferable to assume a protocol if there is one so as a custom rule that could look like this:

Validator::extend('loose_url', function ($attribute, $value, $parameters, $validator) {
    $value = $this->addProtocolIfMissing($value);
    return $validator->validateUrl($attribute, $value);
});

[lagbox]

Hehe, I literally just ran into this today and did an inheritance hack to get around it.
Awesome.