"How many times did we hear statements along the lines of: "Scientific research showed that ..." or "It has been scientifically proven that ..." In doing so, people assume that science is always true. But how reliable is science? A lot of what we call science, and we accept as true, is neither true nor false, and belongs to metaphysics. For a short time (following the publication of Wittgenstein's Tractatus), it looked like we could make a razor-sharp distinction between reliable scientific statements and unreliable metaphysical statements. But Wittgenstein himself challenged that distinction with the posthumous publication of his Philosophical Investigations. Still later, (predominantly French) postmodern philosophy picked up the proposition that there is less truth contained in general science than in a simple literary poem. The days of reliable general theories seemed hopelessly over. Is that so? Has cognitive thinking become impossible? The following is a reflection. The era we live in, at least in the Western world, is called postmodernity. It is characterised by great uncertainty and a sense of increasing insecurity. Uncertainty surrounds unanswered questions related to the future of the planet, to the sustainability of energy supplies, to job security, to family stability, to declining social control, to the increase in the number of asylum seekers, to the existence of a god, and so on. Insecurity is linked to war, to terrorism, to crime. The idea is to study all these phenomena scientifically. But how sure am I that science is still reliable?"