## How does intuitionistic logic differ from classical logic?

Intuitionistic logic, sometimes more generally called constructive logic, refers to systems of symbolic logic that differ from the systems used for classical logic by more closely mirroring the notion of constructive proof.

## Who established the principle of intuitionism?

intuitionism, school of mathematical thought introduced by the 20th-century Dutch mathematician L.E.J. Brouwer that contends the primary objects of mathematical discourse are mental constructions governed by self-evident laws.

**What is intuitionism theory?**

Intuitionism is the philosophy that the fundamental, basic truths are inherently known intuitively, without need for conscious reasoning. Identify the key strengths and weaknesses in their theory, and understand their implications.

**What is the difference between first order and second-order logic?**

Wikipedia describes the first-order vs. second-order logic as follows: First-order logic uses only variables that range over individuals (elements of the domain of discourse); second-order logic has these variables as well as additional variables that range over sets of individuals.

### Why does intuitionistic logic have to include mathematics?

Because intuitionistic logic is an ex post facto construction reflecting the forms of reasoning actually used in intuitionistic mathematics, in order to give a full account of the logic we will need to consider some of the mathematics as well.

### Is intuitionistic propositional logic decidable?

Intuitionistic propositional logic is effectively decidable, in the sense that a finite constructive process applies uniformly to every propositional formula, either producing an intuitionistic proof of the formula or demonstrating that no such proof can exist.

**What are the best models for pure intuitionistic logic?**

For pure intuitionistic logic, there is a very satisfactory model theory based on Kripke models.

**What is the syntax of formulas of intuitionistic logic?**

The syntax of formulas of intuitionistic logic is similar to propositional logic or first-order logic. However, intuitionistic connectives are not definable in terms of each other in the same way as in classical logic, hence their choice matters.