Mathematics makes evident the existence of other minds. No not mathematics as you know it, but at its 'cutting edge'. If you can 'do' advanced mathematics then you can mobilise intuition beyond thought by concentrating all your energy on a problem and through some grace or happy fortuity gaining an answer that seems to come from a kind of super-mind of higher energy and more concentrated vision that what can be attained through the means available to ordinary discursive thought. The example doesn't have to be mathematics, but it has to be a practice that produces a sort of paroxysm in which your entire power of creative imagination is fused. Most of your work is then in the translating of such an immediate insight into the highly compressed language of symbols, in making it readily communicable to your peers. But just as likely you come up with nothing. All the exertions that spark insight fail to produce a result. Then someone else comes along who works on the same problem and they succeed in producing the answer for which you'd been searching. You recognise it immediately, and see that they have been to the 'same place' and by a different turn or a brighter vision, they have found what you failed to find. In their going beyond the fullest extension of your mind, of all its powers, you cannot deny the existence of another mind. This kind of observation refutes solipsism but does not refute idealism, perhaps even makes it more plausible.