D.M. Smith's contributions were pivotal in establishing 'welfare' as a central focus within geography, particularly with the emergence of welfare geography in the 1970s. This subfield arose as a critical response to the perceived limitations of quantitative and positivist approaches, which often overlooked the social relevance and human dimensions of geographical inquiry. Smith, through his seminal works like 'Human Geography: A Welfare Approach' (1977), championed a shift towards understanding and addressing spatial inequalities in human well-being.

Smith's primary contribution was to define welfare not merely in economic terms, but as a comprehensive concept encompassing the quality of life, access to essential resources, opportunities, and overall social justice. He argued that geography should move beyond simply describing spatial patterns to actively analyzing 'who gets what, where, and how.' This involved a normative stance, questioning existing spatial structures and policies that perpetuate disadvantage and advocating for more equitable distributions.

Key aspects of his contribution include:

1. Defining Welfare Geographically: Smith emphasized that well-being is spatially variable. He sought to identify and measure disparities in indicators such as income, health, education, housing, environmental quality, and access to services across different regions and social groups.
2. Focus on Social Justice and Equity: He brought issues of social justice and territorial justice to the forefront, arguing that geographers have a responsibility to understand the causes of spatial inequality and to contribute to solutions that promote fairness and equity in resource allocation and life chances.
3. Critique of Capitalism and State Policies: Smith's work often involved a critical examination of how economic systems, particularly capitalism, and state policies contribute to uneven development and the creation of disadvantaged populations and places.
4. Methodological Integration: While advocating for a human-centered approach, Smith did not entirely dismiss quantitative methods. Instead, he proposed integrating quantitative analysis (to identify and measure inequalities) with qualitative understanding (to grasp the lived experiences and meanings of those inequalities), thereby providing a more comprehensive picture.
5. Ethical Dimension: His work instilled a strong ethical dimension into geographical research, urging geographers to consider the moral implications of their studies and to engage with real-world problems of poverty, deprivation, and injustice.

In essence, D.M. Smith played a crucial role in reorienting geographical inquiry towards a more socially conscious and ethically engaged perspective, making the study of welfare and social well-being a legitimate and vital area of geographical research.