Karl Marx's philosophical anthropology, particularly his concepts of 'human essence' (Gattungswesen or species-being) and 'alienation' (Entfremdung), are central to his critique of capitalism. He argued that capitalism distorts and denies the fundamental nature of humanity.

Human Essence (Species-Being): For Marx, what distinguishes humans from animals is their unique 'species-being,' which is characterized by:

1. Conscious, Creative, and Social Labor: Unlike animals that produce instinctively, humans engage in purposeful, planned, and creative activity. They don't just adapt to nature; they actively transform it through their labor, and in doing so, transform themselves. This capacity for conscious, free, and creative production is the core of human essence.
2. Objectification: Through labor, humans 'objectify' their ideas and intentions into the external world, creating objects that reflect their will and creativity. This process is a means of self-realization and self-expression.
3. Social Nature: Human essence is inherently social. Individuals realize their potential and develop their capacities through interaction, cooperation, and collective production with others. Society is not merely a means for individual survival but a fundamental aspect of human existence.
4. Freedom: The ability to freely and creatively transform the world, to produce not just for immediate physical needs but also for aesthetic and intellectual fulfillment, is a hallmark of human essence.

Alienation (Entfremdung): Marx argued that under capitalism, the very essence of humanity is denied and distorted through the process of alienation. Wage labor, in particular, forces individuals into a condition where their productive activity becomes a source of suffering rather than fulfillment. Marx identified four interconnected forms of alienation:

1. Alienation from the Product of Labor: The worker produces goods that do not belong to them but to the capitalist. The more the worker produces, the more wealth is accumulated by the capitalist, and the more powerful the product becomes over the worker. The product becomes an alien, hostile object, standing opposed to the producer.

2. Alienation from the Act of Production (Productive Activity): Labor under capitalism is not a free, creative, and fulfilling activity but a coerced, monotonous, and dehumanizing means to an end (survival). The worker does not find satisfaction in the work itself but only outside of it. Work becomes external to the worker, a burden rather than an expression of self.

3. Alienation from Species-Being: By being alienated from their creative labor and its product, workers are alienated from their fundamental human essence – their capacity for conscious, creative, and social production. They are reduced to mere instruments of production, their unique human potential stifled.

4. Alienation from Other Human Beings: Capitalism fosters competition rather than cooperation. The relationship between worker and capitalist is one of exploitation and antagonism. Workers are pitted against each other in the labor market, leading to a breakdown of communal bonds and mutual recognition.

Overcoming Alienation: Marx believed that alienation could only be overcome through a revolutionary transformation of society, specifically the abolition of private property and the establishment of communism. In a communist society, the means of production would be collectively owned, and labor would become a free, creative, and social activity once again, allowing individuals to fully realize their human essence.

In summary, Marx's concepts of human essence and alienation are foundational to his critique of capitalism, arguing that the system fundamentally distorts human nature by separating individuals from their creative potential, leading to widespread suffering and dehumanization.