What characterises science on this view is a social decision to allow the world to correct our ideas, and collateral decisions to eschew attempts to insulate those ideas from inconsistency and counter-example. Those decisions are implemented socially in institutions that entrench rules of procedure or method. Thus and only thus is a demarcation established between folk wisdom, social and political opinions and the like, all equally institutional, and science. The difference is not in the results – the claims about the world that issue from time to time from actors in the institutions. Indeed, these may at times look (misleadingly) similar. It lies in the methods by which work proceeds, where method here is construed not simply as a bunch of methodological rules, which is how it is usually presented, but as the deliberate choice and tailoring of methodological rules to specified aims. The choice is institution-building rather than personal. Science is to be identified with an institutionalised aim or set of aims, together with the institutional rules and practices that have been devised to foster pursuit of these aims. These rules serve specifiable purposes and are subject to revision depending upon whether they accomplish such purposes. (Yet Popper did not discuss the reform of scientific institutions, even though he sometimes deplored what science had become (Popper 1972).) It is these rules that enable science to pursue the goals of being objective, realistic, in touch with experience, explanatory, progressive, and causal. Obedience to these rules is what makes the institutions of science different from other social institutions, including those of pseudo-science, magic, logic, and mathematics. It is not doctrines, ideas, or sentences that are scientific or non-scientific; it is certain institutionalised ways of handling doctrines, ideas, and sentences that are scientific or non-scientific. The outcome of this effort is not guaranteed truths, but hypotheses that stand at the end of a chain of conjecture and refutatìon. The main result of the investigation is that we have a deeper and more humbling sense of the underlying problems than that with which we started. 
Nasty little facts of logic
Although science is a social institution, it is not just another social institution. The social institution of science is obedient to special imperatives because it undertakes to explore and explain the world, to in some sense use the world as the ultimate test of its results. Science institutionalises what we know as empiricism, the attempt to learn from experience. The spine of learning from experience is logic: if we have two inconsistent statements, one of them must be false, its negation true. This uncomfortable logical fact, so often allowed to be disregarded or even flouted by other social institutions (e.g. in politics and religion), has to be taken seriously in science. The republic of science makes it difficult to evade or flout contradiction, hence the detection of one is an incipient crisis.