Human behaviour has regular features (for example, all societies develop family systems), which suggests behaviour is guided in some way by social forces that operate over and above the control of individuals (just as behaviour in the natural world is governed by forces such as gravity).
If this is the case then the task of sociologists is to study the ‘ impersonal forces' that structure behaviour – as opposed to the individuals whose behaviour is simply the result of such forces.
If human behaviour is the result of the operation of social forces (rather than individual ‘choice' or consciousness) it follows that the meanings people give for their behaviour are irrelevant if we are to understand that behaviour - mainly because meanings are simply subjective interpretations of the way social forces operate.
Therefore the role of subjectivity is no more significant in the study of society than the subjectivity of an apple when we formulate the laws of gravity.
The goal of a scientific sociology must be to understand how social forces operate, in terms of cause and effect relationships. The sociologists should strive, in Durkheim's words, to understand the nature of ‘social facts' by explaining both the relationship between such facts (how, for example, life chances are related to social class) and their effect upon social behaviour.
Since social forces are objective, quantifiable features of any society, it is possible, using a systematic methodology, to make objective statements about the social world in the same way that physicists, for example, can make objective statements about the natural world.
Sociological research methods must be capable of producing objective, quantifiable data if they are to be effective tools in understanding how and why various social forces operate.
Thus, methods such as questionnaires, structured interviews, content analysis, experiments, observation and statistics are most often used.
Research methods that do not allow easy quantification (such as participant observation) tend to be avoided.
Positivist sociology emphasises the importance of studying social structures (such as how an institution like the education system operates) rather than the actions of individuals. This is because social forces originate at the structural/institutional level of society.
For example, it might examine the functions of an education system (why it exists, what goals it is designed to achieve, how these goals are achieved and so forth) rather than seeking to understand individual experiences of the education system.
This follows because positivists study the way impersonal social forces operate on people. Sociology is not, from this viewpoint, concerned with how people understand their world, nor with the various meanings and explanations people use to try to make sense of the social world.
Sociology is a science because it employs quantifiable methods as a means of understanding the essential, objective features of the social world.