No matter how many instances of a generalization we observe, it does not prove that the generalization is true. You often hear that science is based on the 'facts' while pseudoscience is not. Or you say that religious belief is based on faith, whereas scientific belief is not. Unfortunately, both scientific and non-scientific reasoning go beyond the facts. The demarcation between science and pseudoscience depends only the nature of the reasoning used.
Genuine science involves ampliative inference.
Pseudoscience involves ampliative inference. Therefore, there is no demarcation between science and pseudoscience. The problem of demarcation is to say what is wrong with this argument. The notion of deductively validity is such a central and important concept in philosophy, that is goes by several names. When an argument is deductively valid, we say that the conclusion follows from the premises, or the conclusion is deduced from , or i nferred from , or proved from the premises.