Instrumentalists treat tolerance as means for a further end. Rights-based accounts treat it as a basic value that should therefore be protected as individual right. Constitutivists treat it as an essential feature of good reasoning. The basic claim is that good reasoning is critical reasoning. We can reason critically all we like in our heads, but in practice, we only confront real challenges to our thinking when we submit our reasoning to public scrutiny. To do this we must feel safe that our opinions will be tolerated. So tolerance is a feature of critical reasoning, which is good reasoning.
Constitutive accounts are used mainly in the scientific literature to answer ‘why?’ questions. There are many different types of answers to ‘why?’ questions. For example: ‘Why is the iron hot?’ ‘Because the blacksmith put it in the fire’. The explanation tells us what caused the iron to be hot. ‘Because the blacksmith is preparing to shoe a horse’ tells us the purpose served by heating the iron. ‘Because the molecules in it have kinetic energy’ is a constitutive answer because it tells us that features of the thing, molecules moving, make it how it is, hot; kinetic energy just is heat. The constitutive account of tolerance tries to answer the question ‘Why should we be tolerant?’ by telling us how tolerance is a feature of good reasoning.
For example, Immanuel Kant suggests this constitutive approach to tolerance:
Good reasoning is a matter of debating a topic, of examining what arguments support a position, and whether they are any good. This is the critical part of good reasoning. To do this we need to expose ourselves to different arguments. This exposure is what tolerance is in practice. So the freedom of speech, which both instrumentalists and rights-defenders see as important, on the constitutive account is a deep feature of good reasoning. Clearly more is needed for good reasoning, it is a good idea for example to avoid contradicting yourself. But the freedom that tolerance describes is importantly a feature of good reasoning that benefits from legal protection.
In the quoted passage Kant also says reason’s very existence depends on freedom. This is a point about the peculiar authority of reason. You accept the authority of reason when you reach a conclusion through argument. For example, when you try to make up your mind on whether tobacco should be made illegal, you listen to different views, examine the arguments and then you make up your own mind on the issue. The contrast is with accepting an opinion because someone threatens you, tries to brainwash, hypnotise or bribe you. These things are against reason; they have ‘dictatorial authority’ because they base their authority on force. Freedom from these things is also freedom of thought. This is different to the idea of tolerance, which says that we should have regard for other’s freedom to voice their opinion. This is a negative freedom, a freedom from force of different kinds aimed at denying us freedom of thought and so the opportunity to reason at all.
Maybe the constitutivist faces problems too. For example, she assumes we all value reasoning and want to do it well. Maybe there are some people who prefer to be told what to think and feel more comfortable and happier if they rely on others for guidance. We should be prepared to grant this. Clearly for such people tolerance as the constitutivist conceives it will hold little appeal.
Another problem is that it is too intellectualist a defence. People can express their point of view through their behaviour, dress, lifestyle, not by presenting an opinion. Does the constitutivist defence apply here? Yes, provided behaviour, dress, or lifestyle are things done for reasons. Once we accept this, then what holds for reasoning also holds in these cases.