With regards to Kant's moral philosophy, the most enduring critique is that it is formal, rather than substantive. In other words, Kant is very effective in defining what constitutes a moral act in theoretical terms rather than specifying precisely what we would need to do in certain circumstances. What matters...
With regards to Kant's moral philosophy, the most enduring critique is that it is formal, rather than substantive. In other words, Kant is very effective in defining what constitutes a moral act in theoretical terms rather than specifying precisely what we would need to do in certain circumstances. What matters for Kant, more than anything else, is the logical structure of moral acts rather than their actual content. For critics, this offers a very thin concept of morality, one that does not provide much practical guidance in our everyday lives.
A further criticism of Kantian moral theory is that it concentrates on the act itself to the exclusion of other considerations such as the moral character of the individual or the consequences of a specific action. The first of these criticisms would come from so-called virtue theorists. Following in the footsteps of Aristotle they would argue that substantive moral theories can only be based upon the examination of character. Focusing on a specific moral action, as Kant would have us do, doesn't give us a full picture of what's really happening. All sorts of factors can distort our evaluation of how people behave in certain situations. People can act out of fear, under duress, or under the influence of drugs and alcohol. Actions committed under such negative conditions may be completely out of character for the individual concerned. Yet the Kantian approach leaves the individual moral actor out of the picture, ignoring her character, and separating her from the act she's carried out.
For virtue theorists a far better way of constructing moral theory would be the examination of an individual's character, and how it develops over the course of their lives. This gives us a much deeper and more realistic understanding of what constitutes moral behavior. It re-establishes an intimate link between the moral actor and the individual act, allowing them to be evaluated together. It also recognizes that for moral theory to be substantive it must have a social context and not simply be related to isolated moral acts, as Kantian theory is.